Hull Form and Propulsor Technology for High Speed Sealift [McKesson]

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1
Hull Form and Propulsor Technology
for High Speed Sealift
revised:
13 February 1998
Edited by:
CHRIS B. MCKESSON, PE
J OHN J. M CMULLEN ASSOCIATES , INC.
7726 CLOVER BLOSSOM LANE NE
BREMERTON, WA 98311-3910
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1. Introduction and Lexicon_______________________________________________9
1.1 The Sustention Triangle___________________________________________________9
1.2 The problem with the sustention triangle______________________________________9
1.3 The Sustention Cube_____________________________________________________10
1.3.1 First Axis: Static Lift or Dynamic Lift____________________________________________10
1.3.2 Second Axis: Aero- Lift or Hydro- Lift___________________________________________10
1.3.3 Third Axis: Powered or Passive_________________________________________________10
1.3.4 The Sustention Cube and its Contents____________________________________________10
1.3.4.1 Passive Hydrostatics_______________________________________________________11
1.3.4.2 Passive Hydrodynamics____________________________________________________11
1.3.4.3 Passive Aerostatics________________________________________________________11
1.3.4.4 Passive Aerodynamics_____________________________________________________11
1.3.4.5 Active Hydrostatics_______________________________________________________11
1.3.4.6 Active Hydrodynamics_____________________________________________________12
1.3.4.7 Active Aerostatics________________________________________________________12
1.3.4.8 Active Aerodynamics______________________________________________________12
1.4 Conclusion_____________________________________________________________12
2. Hull Forms / Vessel Types______________________________________________13
2.1 Displacement Ships______________________________________________________13
2.1.1 Hydrostatic Displacement: Ships________________________________________________13
2.1.1.1 Historical Origin_________________________________________________________13
2.1.1.2 Dominant Physics_________________________________________________________13
2.1.1.3 Significant development milestones___________________________________________15
2.1.1.4 Current activities_________________________________________________________15
2.1.1.4.1 Savitsky Monohull (Idea)_______________________________________________15
2.1.1.4.2 Kvaerner Monohull (Design)____________________________________________16
2.1.1.4.3 Sumitomo Monohull (Design)___________________________________________16
2.1.1.4.4 Halter Sponson-Assisted Monohulls (Design)_______________________________17
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2.1.1.4.5 Incat Catamarans (Built)________________________________________________17
2.1.1.4.6 Aker Finnyards Catamaran______________________________________________17
2.1.1.4.7 Asymmetric Catamarans________________________________________________18
2.1.1.5 R&D Needs / Engineering Challenges________________________________________18
2.1.1.6 Transport Effectiveness State of the Art_______________________________________19
2.2 Dynamic Support Ships___________________________________________________21
2.2.1 Hydrodynamic Support________________________________________________________21
2.2.1.1 Planing & Semi-Planing Hulls_______________________________________________21
2.2.1.1.1 Historical Origin______________________________________________________21
2.2.1.1.2 Dominant Physics_____________________________________________________21
2.2.1.1.3 Significant development milestones_______________________________________21
2.2.1.1.4 Current activities______________________________________________________23
2.2.1.1.5 R&D Needs / Engineering Challenges____________________________________26
2.2.1.1.6 Transport Effectiveness State of the Art____________________________________26
2.2.1.2 Ski Craft________________________________________________________________28
2.2.1.2.1 Historical Origin______________________________________________________28
2.2.1.2.2 Dominant Physics_____________________________________________________28
2.2.1.2.3 Significant development milestones_______________________________________28
2.2.1.2.4 Current activities______________________________________________________29
2.2.1.2.5 R&D Needs / Engineering Challenges_____________________________________30
2.2.1.2.6 Transport Effectiveness State of the Art____________________________________31
2.2.1.3 Hydrofoils_______________________________________________________________31
2.2.1.3.1 Historical Origin______________________________________________________31
2.2.1.3.2 Dominant Physics_____________________________________________________31
2.2.1.3.3 Significant development milestones_______________________________________32
2.2.1.3.4 R&D Needs / Engineering Challenges_____________________________________36
2.2.1.3.5 Transport Effectiveness State of the Art____________________________________36
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2.2.2 Aerodynamic Support_________________________________________________________36
2.2.2.1 Aircraft_________________________________________________________________36
2.2.2.2 Ekranoplans_____________________________________________________________36
2.2.2.2.1 Historical Origin______________________________________________________36
2.2.2.2.2 Dominant Physics_____________________________________________________37
2.2.2.2.3 Significant development milestones_______________________________________37
2.2.2.2.4 Current activities______________________________________________________37
2.2.2.2.5 R&D Needs / Engineering Challenges_____________________________________38
2.2.2.2.6 Transport Effectiveness State of the Art____________________________________38
2.3 Powered Support Ships___________________________________________________38
2.3.1 Hydrostatic Support___________________________________________________________38
2.3.1.1 Air Cushion Vehicles______________________________________________________38
2.3.1.1.1 Hovercraft___________________________________________________________38
2.3.1.1.2 Surface Effect Ships___________________________________________________39
2.3.2 Aerostatic Support____________________________________________________________46
3. Propulsors___________________________________________________________47
3.1 Waterjets______________________________________________________________47
3.1.1 Dominant Physics____________________________________________________________47
3.1.2 State of Development_________________________________________________________47
3.1.3 Current Activities & R+D Needs________________________________________________47
3.1.4 Propulsive Efficiency State of the Art_____________________________________________47
3.2 Propellers______________________________________________________________48
3.2.1 Fully Wetted Propellers________________________________________________________48
3.2.2 Ventilated propellers__________________________________________________________48
3.2.2.1 Dominant Physics_________________________________________________________49
3.2.2.2 State of Development______________________________________________________49
3.2.2.3 Current Activities & R+D Needs_____________________________________________49
3.2.2.4 Propulsive Efficiency State of the Art_________________________________________49
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4. Centers of Activity in High Speed Ships___________________________________51
4.1 Major Conferences and Shows_____________________________________________51
4.1.1 Fast Ferry International________________________________________________________51
4.1.2 FAST______________________________________________________________________51
4.1.3 HIPER_____________________________________________________________________51
5. Enabling Technologies________________________________________________535.1 Hydrodynamics_________________________________________________________53
5.2 Structure_______________________________________________________________53
5.3 Propulsion______________________________________________________________53
5.4 Electrical and Auxiliary Machinery_________________________________________53
5.5 Command and Control___________________________________________________53
6. Appendices__________________________________________________________55
6.1 Membership of subgroup “Hullforms, Hydrodynamics, and Propulsors”__________55
6.2 McKesson white paper on sealift state of the art_______________________________59
6.3 State of the Art Propulsors for High-Speed (40-50 knot) Ships___________________63
6.4 Comments on Resistance of Different Concepts_______________________________71
6.5 Halter Marine Group Sponson Assisted Monohull_____________________________75
6.6 Notes on The Dominant Physics of High Speed by Dr. Daniel Savitsky____________81
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Hull Form and Propulsor Technology
for High Speed Sealift
This report presents an introduction and summary of the state of the art of high speed ship hull form and
propulsor technologies. This report is the product of the High Speed Sealift Technology Workshop held
21-23 October 1997.
This report is intended to serve as a resource for persons contemplating the development or employment
of high speed ships for cargo transport.
The High Speed Sealift Technology Workshop gathered approximately 200 persons considered expert in
various technologies relevant to high speed sealift. These delegates were divided into subgroups with
particular focus areas. This report deals specifically and exclusively with the discussions in the
Hullforms, Hydrodynamics, and Propulsors subgroup. The membership of this group is listed in
Appendix 6.1.
Over a period of two an a half days these delegates hammered out a consensus of what level of
performance is attainable in the near, mid, and far terms. This report attempts to present that consensus.
The consensus is amplified by including relevant background material, references, etc. Also included is
an indication of the other resources available for continued study of this subject.
The discussions at the workshop were focused by a nominal mission statement. The sealift need was
presented as:
· Speed:40 - 100 knots
· Range:5,000 - 10,000 n. mi
· Cargo: 2,000 - 5,000 short tons
· 75,000 - 150,000 square feet
· Other: Shallow Draft
The above figures present design challenges. One white paper, prepared by McKesson and distributed at
the workshop (included as Appendix 6.2) shows that for a certain state of the art it is impossible to
develop a ship with a range greater than 7800 miles. This conclusion is driven entirely by what level of
ship performance - specifically L/D - represents the state of the art. McKesson’s analysis is flawed, in that
it ignores the effect of fuel consumption on ship weight (and hence drag) as pointed out by Doctors,
Appendix 6.4. Nonetheless, Doctors enhancement merely changes the numerical value of the limits (such
as the 7800 n. mi above) while concurring with the basic role played by L/D.
It was in order to gather a consensus regarding L/D state of the art that the group met.
The product of the workshop was a consensus. Consensus implies that a variety of opinions were distilled
down to one. Of course, there will be cases wherein a member of the group will feel that his opinion is
not adequately represented. In recognition of the legitimacy of these opinions we have provided for
inclusion of “minority positions.” The group wishes it clearly understood that such minority positions do
not represent a simple inability to manage the committee, but are rather a natural outcome of the
uncertainties found in this study.
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1. Introduction and Lexicon
The following material was prepared by Chris McKesson of John J. McMullen Associates in order to
provide a common lexicon for the workshop.
1.1 The Sustention Triangle
The "sustention triangle" is a commonly used device for characterizing ship types. This triangle is
illustrated in Figure 1. It is a conceptual device for understanding what makes the boat float. Traditional
ships float because they are immersed in water and buoyed up by Archimedes' force. This is called
"buoyant lift" and occupies the lower left corner of the triangle.
There are other ways to hold ships up. The reader may be familiar with hovercraft, for example, where
the ship is lifted on a bubble of air. Hovercraft have operated between England and France for thirty years
now. Hovercraft are examples of "powered lift" craft, as depicted on the lower right corner of the triangle.
Another lift type one may be familiar with is "dynamic lift". A water ski works by dynamic lift. It does
not float, but when pulled fast enough through the water it generates a good lift force and raises the entire
payload up out of the water. Hydrofoils and hydroplanes are both dynamic lift craft.
1.2 The problem with the sustention triangle
The sustention triangle is a good concept, one that has been in use for decades and has done good service.
It does, however, have some flaws. In general these flaws may be characterized by one typical example:
The model does not distinguish between hydrofoils and WIGs. Both of these are dynamic lift craft.
MONOHULLCATAMARAN
FOIL ASSISTED
CATAMARAN
SURFACE
HYDROFOILHYDROFOIL
WAVEPIERCER
SUBMERGED
PIERCINGFOIL
SWATH
SURFACE
HOVERCRAFT
EFFECT SHIP
BUOYANT LIFT POWERED LIFT
DYNAMIC LIFT
Figure 1 - This figure illustrates the conventional sustention triangle. This is a concept model which
characterizes a ship by its means of support.
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1.3 The Sustention Cube
It is the author’s conviction that a “design space” should consist of mutually orthogonal axes. Consider
therefore what the axes of the sustention space are. The result of this consideration leads directly to the
sustention cube, as follows:
1.3.1 First Axis: Static Lift or Dynamic Lift
Does the lift of the craft require that the craft be moving? The test for this is whether the craft’s lift
balance changes when forward speed is applied. Obviously planing craft change their lift balance as they
come up to speed, thus clearly making them dynamic lift craft. Barges, on the other hand, may be the
epitome of passive lift craft
1.3.2 Second Axis: Aero- Lift or Hydro- Lift
Is the lift created by the displacement of air or of water? Barges are hydrostatically supported. Airships
(blimps) are aerostatically supported. Hydrofoils and planing craft are hydrodynamically supported.
Airplanes and WIGS are aerodynamically supported.
1.3.3 Third Axis: Powered or Passive
Alternatively these terms may be “active” or “passive.” The test for this is whether the lift is due to the
active motion of some component of the craft, or on the other hand is the lift due to the basic shape
(geometry) of the craft? Most ships get their (static) support from their hull form, thus making them
passive hydrostatic craft. Note that planing craft and airplanes should be labeled as passive craft. They
require power to generate the speed that activates their lift, but the lift itself is the result of the shape of
the bottom, or the shape of the wing.
1.3.4 The Sustention Cube and its Contents
The last description above now leads us into discussions of the total shape of the sustention cube. Figure 2
presents a depiction of the cube. The corners are defined by combing the following pairs, to label the
eight corners:
· Passive or Active
· Hydro- or Aero-
· -Static or -Dynamic
 Thus the eight corners are:
· Passive Hydrostatics
· Passive Hydrodynamics
· Passive Aerostatics
· Passive Aerodynamics
· Active Hydrostatics
· Active Hydrodynamics· Active Aerostatics
· Active Aerodynamics
Let us now consider the population of each of these corners in turn:
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ACTIVE
PASSIVE
AERO-HYDRO-
-DYNAMIC
-STATIC
Figure 2 - This figure illustrates the sustention cube, a new model which offers broader applicability
by covering more of the design space than the triangle.
1.3.4.1 Passive Hydrostatics
Conventional ships and barges.
1.3.4.2 Passive Hydrodynamics
Planing craft (their shape determines their efficiency.) Hydrofoils.
1.3.4.3 Passive Aerostatics
Blimps
1.3.4.4 Passive Aerodynamics
Airplanes and WIGs
1.3.4.5 Active Hydrostatics
Can we imagine a craft which has some moving component that would generate lift, not dependent on
forward speed? Consideration of this corner of the cube leads to the concept of “hydrocopter.” Consider
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a machine that looks something like a helicopter with its rotor in the water. Would this not be an active
(it has moving parts) hydro- (obviously) -static (its lift balance doesn’t change with speed) craft?
1.3.4.6 Active Hydrodynamics
Continuing the excursion into the unknown an attempt has been made to conceive a craft using active
hydrodynamics. Consider what this means: It requires ahead speed to make lift, it uses moving parts, and
it does this in the water. The only concept this author can imagine is a sort of hydrofoil using Fletner
rotors. Like a hydrofoil it requires ahead speed, but it also requires the rotation of the rotors to generate
Magnus-effect circulation.
1.3.4.7 Active Aerostatics
This is a helicopter: Requires power, but does not require ahead speed.
1.3.4.8 Active Aerodynamics
Perhaps the autogyro: It requires ahead speed and moving parts to fly.
1.4 Conclusion
The Sustention Triangle has done good service for decades as a mental model of the advanced vehicle
design space. This note has proposed a logical expansion of the venerable triangle which includes all
existing vehicle types. It also, like a good mental model, can be used to provoke thought about new
vehicle types.
This is only a small contribution to the literature of advanced vehicle design, but in the interest of more
comprehensive models the author is pleased to offer it.
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2. Hull Forms / Vessel Types
In this section are presented discussions of each of the several vessel types discussed at the workshop.
This section is organized along the axes of the sustention cube discussed in Section 1.
An attempt has been made to distinguish between design concepts and actual built craft. The reader is
counseled to be alert to references to “idea” “design” or “built” in this regard.
Wherever possible each discussion of a craft type ends with a presentation of the Transport Factor (TF)
state of the art for that craft type1. TF values are presented in tabular form, and are graphed against both
dimensional speed and against non-dimensional speed. The use of two separate speed scales identifies the
role of “economies of scale” in this analysis.
The TF versus Speed graphs also include a contour which approximately marks the boundary of the
current state of the art. The values for this contour were provided by Dr. Kennell in private
correspondence. The purpose in including this curve is only to aid the reader in flipping back and forth
between different graphs. It is in no way intended as a measure or critique of any craft.
In the graphs of TF versus Froude number a similar comparative line is included. This line is not
identical to Dr. Kennell’s line.
2.1 Displacement Ships
2.1.1 Hydrostatic Displacement: Ships
2.1.1.1 Historical Origin
It is impossible and unnecessary to present here a history of the development of the displacement hull
form. Let it suffice to point out that this hull concept dates to prehistoric times.
2.1.1.2 Dominant Physics
The lift/drag performance of displacement ships at high speeds is dominated by wave making drag. A
displacement form moving through the water pushes the water aside as it moves. This disturbance of the
water requires energy, specifically propulsive energy from the ship.
Two major parameters affect the wavemaking resistance of the ship: Speed and Slenderness.
Ship wavemaking drag increases rapidly with increasing speed. It is not possible to state a specific law
for this increase - a law that holds true for all ships - but it is common to refer to a cubic increase in drag
with speed. Specifically, it is commonly understood that ship propulsive power will increase as the cube
of ship speed. Thus a doubling of ship speed will require an octupling (8=23) of installed power.
 
1 Transport Factor is a measure of merit developed by Dr. Colen G. Kennell of the David Taylor Model
basin. Dr. Kennell’s paper “Design Trends in High Speed Transport” was distributed to workshop
attendees. Transport Factor is defined as:
TF = 1.6878 / 550 * 2240 * (Full Load Displ. in Long Tons) * (Speed in knots) / (Total Installed SHP)
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This cubic relationship is close to true for “normal” speeds. But at very high displacement speeds the
curve becomes even more steep. It is common for naval architects to limit their investigation of
displacement ships to a speed length ratio of about 1.30. (Speed length ratio is the ratio of ship speed in
knots divided by the square root of the ship’s length in feet. This is also known as the Taylor quotient Tq,
after ADM David W. Taylor.) Above a speed-length ratio of 1.3 the increase in drag with increasing
speed becomes greater-than-cubic.
Speeds greater than 1.3 are present in some displacement hull designs. The dominant question is “how
important is wavemaking?” for the particular design. If one can make the wavemaking problem of lesser
importance overall, then one may more readily consider speeds higher than Tq=1.3.
The tool (or “one tool”) for this is ship slenderness. A slender ship disturbs the water less, and thus has
less wavemaking drag. It also has more surface are and thus more frictional drag, but this does not suffer
the same steep growth with speed as does the wavemaking drag. Slenderness is measured as the Length
over Displacement ratio (L/Ñ1/3).
One participant’s graph of the behavior of several slender ships is presented in Figure 3 below. It clearly
shows that, for a constant 7500 ton displacement, increasing the slenderness leads to increased speed, at a
given power level. Note also that it clearly shows the diminishing returns of this approach: It is
questionable whether extending the range beyond the slenderness of 12.0 would result in any further gains
in speed.
Figure 3 - Parametric investigation of the effect of slenderness upon total drag for a 7500t monohull
The benefits of slenderness are also utilized in the catamaran concept. Here two slender hulls are joined
in a fashion that provides good arrangeability and stability.
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2.1.1.3 Significant development milestones
Frequently mentioned as a high performance displacement ship is the liner SS United States. One
conference participant provided data both on the United States herself, and on what might be
accomplished in developing a 1997 version of this ship, using latest enabling technologies.
United States as built had a sustained speed of 35 knots on a power level of 161,500 hp. Her machinery
plant was capable of 240,000 hp, of which only approximately two-thirds were used for sustained speed.
Her other characteristics are as follows:
LBP 940 ft
Displacement, Full Load45,450 LT
Fuel Capacity 10,306 LT
Range 10,000 n.mi
Cargo Capacity 5,750 LT
Sustained Speed 35 knots
Power at Sustained Speed161,500 hp
It may be postulated that the following improvements are possible for United States:
Item Reduction in
Power at 35 knots
Add bow bulb 5%
Add Stern Flap 8.5%
Use high strengthsteel
and gas turbine machinery
(weight reduction) 5%
Increase propulsive
efficiency through use of
contra-rotating propellers 11%
TOTAL 29.5%
Given the above stated improvements, United States’ performance would increase as shown in Figure 4
2.1.1.4 Current activities
Workshop participants presented several ideas, design concepts, and built craft for a displacement-hulled
fast sealift ship. These are discussed below:
2.1.1.4.1 Savitsky Monohull (Idea)
A simple but insightful proposal is for a very large monohull. If one limits Taylor quotient to 1.3, then a
50 knot speed requires a length of approximately 1500 feet. Such a ship, it was claimed, would have
approximately the following characteristics:
LBP 1500 ft
Range 10,000 n.mi
Fuel Load 10,000LT
Cargo Capacity 20,000LT
Power 500,000hp
Slenderness
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Figure 4 - Possible improvements in performance of SS United States using latest technology
Note that this idea does not rely on slenderness, but on using size to lower the Tq associated with 50
knots. This becomes particularly apparent if one compares this ship’s TF performance on Figure 5 versus
Figure 6.
2.1.1.4.2 Kvaerner Monohull (Design)
Figure 3 above presents summary data on the slender monohull studies conducted by Kvaerner Masa
Yards. This data might be used to represent the following two hypothetical 50-knot ships, both based on
the contour of Mc=12.0:
Basis Extrapolated
Ship 1 Ship 2
LBP 235 m 1500 ft
Displacement 7,500 tonne 54,400LT
Speed 38 knots 50 knots
Power 60 MW 465,000 SHP
A further example of current slender ship projects are the BathMax slender ships developed jointly by
Bath Iron Works and Kvaerner Masa Yards.
2.1.1.4.3 Sumitomo Monohull (Design)
A comprehensive discussion of a displacement type slender high speed ship was presented by Takarada et
al at FAST 93. The resulting design had the following characteristics:
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LBP 228 m
Beam 23 m
Draft 8.5 m
Range 5,000 n.mi
Speed 50 knots
Cargo Capacity 1,000 LT
Power 6 x 33,100kW
Displacement 23400 tonnes (Estimated by McKesson)
Slenderness 8
2.1.1.4.4 Halter Sponson-Assisted Monohulls (Design)
Since conclusion of the workshop one participant provided data on a family of slender hulls, where
stability is improved by fitting sponsons or outriggers. This work, previously published by Nigel Gee &
Associates (Fast Ferry International, May 1997), was not discussed at the workshop but is reproduced in
Appendix 6.5.
2.1.1.4.5 Incat Catamarans (Built)
The slender ship concept is also descriptive of the catamaran. Catamaran state of the art may be described
by the following data points:
VESSEL FULL LOAD INSTALLED SERVICE SPEED SLENDERNESS
DISPLACEMENT PROPULSION AT FULL LOAD (per hull)
POWER CALM WATER
74 m 850 tonnes 4 x 4050 kW 36.0 knots 9.8
81 m 1100 tonnes 4 x 5500 kW 38.2 knots 9.9
86 m 1250 tonnes 4 x 7080 kW 42.8 knots 10.0
91 m 1400 tonnes 4 x 7080 kW 42.0 knots 10.3
96 m (design)1700 tonnes 4 x 7200 kW 37.8 knots 10.1
130 m (design)5000 tonnes 4 x 22000 kW 63. knots 9.6
Correspondence with INCAT has suggested that catamaran L/D performance can be described by the
curve: L/D = 25600 x (Speed in knots)-2.
INCAT are also pursuing the development of partial aerodynamic support (See the discussion below under
EkranoCat, Section 2.2.2.2.4). They expect an overall L/D of 15 at 80 knots for such a craft. Doctors’
work suggests that the L/D will maintain at higher speeds, as the aerodynamic contribution becomes
stronger.
2.1.1.4.6 Aker Finnyards Catamaran
The largest existing catamaran is the Aker Finnyards STENA HSS 1500, with the following
characteristics:
LOA 125 m
B 40 m
Draft 4.5 m
Speed 40 knots
Power 68 MW
Displacement 4500 tonnes (Estimated by McKesson)
Deadweight 1500 tonnes
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Payload 1300 tonnes
Fuel Load 200 tonnes
Range 500 n.mi
Slenderness 9.5 per hull, based on displacement above.
2.1.1.4.7 Asymmetric Catamarans
Catamarans at high Froude number have substantial wavemaking drag. As such many researchers have
looked for means of reducing wavemaking drag. One recently studied avenue of research is the
asymmetric catamaran. By staggering the hulls of the craft relative to each other a favorable interference
may be set up which reduces total drag.
This was proposed most recently in a paper by Söding at FAST 97. He reports that at a Froude number of
approximately 0.43 (corresponds to a Taylor quotient of 1.44) he attained a 50% reduction in the drag of a
catamaran.
The “problem” in Hr. Söding’s work is that the catamarans he tested were not at the limits of slenderness.
His approach of staggering the hulls results in an increase in the overall length of the ship. It has been
suggested (by Dr. Doctors in particular) that simply stretching the ship to this increased length, with the
attendant increase in slenderness, would result in an equal or greater reduction in drag. Unfortunately a
comprehensive comparative research program has not been carried out.
2.1.1.5 R&D Needs / Engineering Challenges
A long slender ship, particularly one with extreme characteristics, suffers from the following
disadvantages:
· Difficult to turn
· May be unstable, requiring active stabilization. Some concepts may be statically unstable,
which would require changes in international rulemaking, since all such rules currently
require some level of passive static stability.
· May be of too large draft to be interesting. Few designers have provided draft data, but
simple parametrics have suggested that draft may become quite large - say over 40 feet - at
displacements of 60,000 LT +.
· At 1500’ length there are limited production and maintenance facilities.
 
 Development of such a ship would benefit from the following R&D efforts:
· High Rn Friction studies
· Correlation allowance reduction through the use of very smooth surfaces
· Comprehensive study of the benefits of staggered hull arrangements versus increased ship
length
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2.1.1.6 Transport Effectiveness State of the Art
Data has been added to the transport factor data file to represent the updated United States, the 1500 foot
slender monohull, the catamarans, and several derivative concepts. The data is presented in Table 1,
below. Plots of Transport Factor versus Speed and versus Volume Froude Number is given in Figures 5 &
6.
Table 1 - Characteristics of State of the Art displacement ships
Ship or Concept Speed
(knots)
SHP Range
(n.mi)
Payload
(LT)
Displacement
(LT)
Transport
Factor
Aker Finnyards HSS 1500 40. 95000 500 1300 45002 13.02
Aker Finnyards HSS 1100 (design) 40. 65000 400 600 0.00
Aker Finnyards Swath 2000 (design) 40. 125000 1000 2000 6000 13.20
INCAT 130m (design) 63 118008 4300 2000 5000 18.35
INCAT 130m (design) 58 93870 4300 2000 0.00
INCAT 96m (design) 37.8 39500 1700 11.18
INCAT 91m 42 38855 1400 10.40
INCAT 86m 42.8 38855 1250 9.46
INCAT 81m 38.2 30200 1100 9.56
INCAT 74m 36 22222 850 9.47
Sumitomo Monohull (design) 50 266300 5000 1000 234002 30.18
Kvaerner Parent (design) 38 80460 7380 23.96
Kvaerner Offspring (design) 50 465000 54400 40.21
SS United States - As Built 37.25 240000 10000 5750 45450 48.49
SS United States 1997 (design) 39.5 240000 10000 5750 43178 48.85
1500'Slender Monohull (design) 50 525000 10000 20000 67000 43.86
 
2 Displacement estimated by the editor.
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Displacement Hulls
0.00
20.00
40.00
60.00
80.00
100.00
120.00
140.00
160.00
180.00
200.00
0 10 20 30 40 50 60 70 80 90 100
SPEED (knots)
T
F
Figure 5 - Transport Factor of Displacement Ships versus Speed. Open spots mark designs. Filled spots
mark ships which have been built.
Displacement Hulls
0.00
20.00
40.00
60.00
80.00
100.00
120.00140.00
160.00
180.00
200.00
0 0.5 1 1.5 2 2.5 3 3.5 4
Volume Froude Number
T
F
Figure 6 -Transport Factor of Displacement Ships versus Froude Number. Open spots mark
designs. Filled spots mark ships which have been built.
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2.2 Dynamic Support Ships
2.2.1 Hydrodynamic Support
2.2.1.1 Planing & Semi-Planing Hulls
The consensus of the workshop attendees, without much discussion, was that conventional fully planing
hull forms are not suitable for consideration for the sealift mission because of their inherently low L/D
ratio. No further space will be devoted to them. Discussion in this section focuses on the Semi-Planing
concept. Note also that Ski craft, which are in fact fully planing, are considered in Section 2.2.1.2.
2.2.1.1.1 Historical Origin
Planing hulls trace their origin to the invention of the internal combustion engine. Only when fairly high
power / light weight machinery became available was the dynamically supported craft practical. Planing
and semi planing craft have received considerable attention since the first decades of this century.
2.2.1.1.2 Dominant Physics
A planing hull is lifted by the generation of a high pressure on the bottom. Unlike an airplane wing there
is flow over only one surface - the bottom - and in consequence a planing hull is less efficient than a wing.
The poor lift-to-drag ratio of a planing hull results from a) lift on the bottom surface only and b) poor
aspect ratio. A separate problem is the poor ride in rough water.
The dominant concerns in planing hull naval architecture concern:
1. The proper placement of the pressure center, so that the boat rides at an appropriate and stable
attitude.
2. The shaping of the planing surface for maximum lift-to-drag ratio: Generally the bottom is shaped
such that the wetted portion of the planing surface possess a fairly low aspect ratio, being several
times longer than it is wide. A gain in aspect ratio may be accomplished by incorporating steps in
the bottom, but the resulting aspect ratio is unfortunately still quite low.
3. Control or elimination of drag effects from secondary phenomena such as spray.
A distinction is introduced between Planing and Semi-Planing hulls. Semi-Planing hulls receive only a
(small) portion of their support from dynamic effects.
For purposes of this workshop the line between Planing and Semi-Planing was drawn at a volume-Froude
number of 3.
2.2.1.1.3 Significant development milestones
A major milestone in the development of large semi-planing ships is motoryacht Destriero. Destriero is a
67m private motoryacht, depicted in Figure 7 below.
22
Figure 7 - Motoryacht Destriero, holder of the transatlantic speed record.
Destriero’s principal characteristics are as follows:
LOA 67.7 m
LBP 60.0 m
BOA 13.0 m
Draft 5.21 m
Hull Construction Aluminum
Full Load Range, SS 4 3,000+n.mi
Displacement approx 1000tonnes
Machinery 3 x GE LM 1600
3 x KaMeWa 125waterjets
Power 38,535kW
Destriero successfully established the speed record for transatlantic crossing in 1992. She averaged 53+
knots, over 3100 n.mi, while carrying a “payload3” of 100 tonnes. During this crossing she consumed
approximately 500 tonnes of fuel. She also demonstrated that weight reduction will lead to speed rise: At
her departure, at a weight of about 1100 tonnes, her full power speed was about 42 knots. At the finish
line, at a weight of about 550 tonnes, her speed was 63 knots. This is illustrated particularly in the speed-
time profile for the crossing, presented in Figure 8.
 
3 This payload was an excess of fuel of 100 tonnes, which was placed on board because the master didn’t
trust the designer’s assurance that it wasn’t necessary. Having now demonstrated the performance, such a
crossing could be duplicated without carrying this 20% fuel reserve.
23
Figure 8 - A speed-time history of Destriero's Atlantic crossing, showing the speed rise as fuel was
consumed
2.2.1.1.4 Current activities
The state of the art large semi-planing cargo transport is surely the Fast Ship Atlantic (FSA) project. This
project has been the subject of many analyses and reports, which will not be repeated here.
The thrust of the workshop discussion was to establish the credibility of the FSA performance claims. At
one point discussion also entered into assessment of the economics of FSA service, but workshop
participants were admonished by the sponsors not to deal in economics, as this was the subject of separate
tasking. The consensus of the workshop participants was that the performance claims of FSA are
credible.
It is also valuable to call attention to the FSA-derivative sealift ship developed as a 13A project by USN
personnel studying at MIT, a design designated “SOCV”. This project is described in the students’ report,
available at http://web.mit.edu/welsh/www/13a/sealift.htm. That study presents the development of a
design with the following characteristics:
Ship Characteristic Quantity
Design Full Load Displacement 39,475 tonnes
Length Overall (LOA) 260 m
Length Between Perpendiculars(LPP) 229 m
Beam (BWL) 45 m
Draft at Design Displacement(T) 10.5 m
Depth at Station 10(D10) 32 m
Endurance In Commercial Mode 4000 nm @36.5 knots
Endurance In Sealift Mode 12,000 nm @ 27 knots
Maximum Speed 37.5 knots
Max Sustained Speed (@ Seastate 6) 36.5 knots
Commercial Cargo Capacity 1528 TEU @ 6.35 net tonne / TEU
Military Cargo Capacity 10,000 long tons; 200,000 sq ft RO/RO
Propulsion Plant: 6 GE LM-6000, 240 MW (320,000 BHP)
Power Transmission: Mechanical Gearsets; Waterjet Propulsor
Bow Thruster: One Tunnel @ Bow
Ship Service Power: Allison 501-K34 @ 2500 KW ea.
It is interesting to note that the FastShip SOCV, in its sealift mode, has an overall lift-to-drag ratio of 22.4
(including the effect of the propulsive coefficient.) This is at a speed of 27 knots, which does not meet the
24
speed goal of the workshop. These figures emphasize the difficulty of achieving the required efficiency
with a displacement of semi-planing design.
One particular point of discussion both in the 13a study and at the workshop was the ability of the ship to
maintain speed in waves. Figures 9, 10 and 11 were presented at the workshop, which show that because
of her high power level the FSA is able to maintain speed. Other ships, wherein minimum calm water
drag has been assiduously sought, do not have the power to maintain speed in high seas. This results in
schedule uncertainty.
Figure 9 - Involuntary Speed Reduction in Head Seas - FastShip design compared with two other
displacement ships.
25
Figure 10 - Added power in waves - FastShip TG-770 design compared with SL-7.
H1/3=4.88m, Tz=8.5 secs
Figure 11 - Changes in power requirement, calm water to 4.85m H1/3 bow sea, FastShip design vs
SL-7
26
2.2.1.1.5 R&D Needs / Engineering Challenges
The semi-planing ships discussed, up to and including the FastShip Atlantic design, are technologically
acheivable today. There are no critical R&D needs. They represent Near Term performance capabilities.
Advances above Near Term performance levels are probably limited by the availability of higher powered
machinery units and propulsors.
2.2.1.1.6 Transport Effectiveness State of the Art
The designer of Destriero, Mr. Donald Blount, prepared and provided the following figure depicting the
capability of Destriero if used as a cargo carrier. It presents contours of range and cargo load for three
different design points: Full Load (FL = 550 tonnes fuel), Mean Load (ML = ½ fuel), and Overload (OL
= 110% fuel). In all cases speed is 50 knots in SS 4.
Data has been added to the transport factor data file to represent Destriero and FastShip. The data is
presented in Table 2, below. A plot of Transport Factorversus Volume Froude Number is given in Figure
13.
Figure 12 - The transport effectiveness of m/y Destriero
27
Table 2 -Characteristics of State of the Art semi-planing ships
Ship or Concept Speed
(knots)
SHP Range
(n.mi)
Payload
(LT)
Displacement
(LT)
Transport
Factor
Destriero 53.1 60000 3106 1054 6.41
Destriero 56.31 52300 795 5.88
Destriero 57.2 40570 566 5.49
Destriero 61.8 50560 590 4.96
Destriero 50 51675 2000 260 1100 7.32
TG-770 (design) 42 480000 4800 13600 30480 18.33
SOCV (design) 36.5 320000 4000 10000 39475 30.95
Semi-Planing Hulls
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
0 10 20 30 40 50 60 70 80 90 100
SPEED (knots)
T
F
Figure 13 - Transport factor of Semi-Planing hulls versus Speed. Filled spots designate ships which
have been built. Open spots designate designs.
28
Semi-Planing Hulls
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
Volume Froude Number
T
F
Figure 14 - Transport factor of Semi-Planing hulls versus Froude Number. Filled spots designate
ships which have been built. Open spots designate designs.
2.2.1.2 Ski Craft
2.2.1.2.1 Historical Origin
2.2.1.2.2 Dominant Physics
Ski craft are a form of planing craft. As the title implies, they use long slender skis as planing surfaces.
They are fully dynamically supported. Ski craft will suffer from the very low aspect ratio of their planing
surfaces, which implies large induced drag. The very slenderness of these surface may lead to benefits to
ride quality in rough water.
2.2.1.2.3 Significant development milestones
A milestone in ski craft development was the ski-supported jet seaplane developed in the 1960’s - Figure
15. Many people have studied ski craft, including workshop participant Dr. Daniel Savitsky. Dr.
Savitsky said, in private correspondence to the editor for inclusion in this report:
“The hydrodynamics of hydroskis aare well understood and documented in
many publications available in the open literature. Assuming that the ski runs
at an optimum trim angle of 4.5 degrees, has zero friction (obviously
ridiculous) and has an OPC of 0.65, then its TF will be approximately 8.0.
This is not an attractive TF despite the fact that all friction drag has been
neglected. ... I believe that the proposers should provide some documentation
29
to support the reality of their assumptions prior to including these concepts in
our report. Otherwise you might present them as “unsubstantiated claims”
which some members of the workshop did not accept.”
Figure 15 - The 1960 Convair Y2FY Sea Dart - Ski supported jet seaplane
2.2.1.2.4 Current activities
Ski Craft have been actively proposed by Newport Technologies Ltd. They have a website depicting
several design concepts at http://members.aol.com/advtransys/private/fp.htm. There are no photographs
on this site of actual built craft, however discussions in the workshop indicated that the company has a 10-
foot demonstration craft with surprisingly good performance. The testcraft has the following
characteristics:
LOA 10 ft
Displacement 514 lbs
L/D 2.6
Speed 29 knots
This testcraft has been towed up to 108 knots, at 1400 lbs all-up weight. No drag data has been provided,
except the anecdotal evidence that “one man could pull in the tow line.”
The Newport Technologies testcraft was tested in the David Taylor Model Basin, but only at speed up to
about 30 knots. Up to this speed it exhibited behavior similar to any planing craft. This is consistent with
the L/D value quoted above.
From this testcraft the developers have conceived several variants. One is depicted in Figure 16 below.
This is a proposed 27 foot sport boat. Newport Technologies reports that they have secured a contract to
build two 83-passenger 65-foot ferries, with a service speed of 100 knots. The boats will weigh 83000 lbs
and have 4000 hp installed. Construction is scheduled to start in mid January 1998.
Figure 16 - Newport Technologies proposed 27-foot ski-supported sport boat
30
The inventors have scaled the performance of their testcraft and arrived at a proposed concept for a
vehicle with the following characteristics:
LOA 410 ft
LWL 360 ft
Beam 150 ft
Draft - skis up 14 ft
Draft - skis down 40 ft
Power 4x92,000lb thrust turbofan (GE 90)
Speed 250 knots
Range 13015 n.mi
Displacement 10,000 tons
Fuel Capacity 2,000 tons
Payload 8,000 tons
The performance claims for this craft were met with a certain amount of incredulity during the workshop.
Not all of this incredulity was expressed during the session - several people spoke to the session chairman
privately to express their concern. However all acknowledged that it would be hasty to make a judgement
in the absence of good data. It was unanimously decided that the Newport Technologies testcraft should
be instrumented and its performance conclusively and comprehensively measured. The ferries mentioned
above would make excellent test platforms if they are indeed built.
2.2.1.2.5 R&D Needs / Engineering Challenges
The inventors of the ski craft acknowledged a need for better characterization of friction at very high
Reynolds’ Numbers, corresponding to speeds up to 300 knots.
Also, as mentioned above, there is insufficient basic understanding of the performance of ski-craft.
Based on illustrations provided on the website for a cargo transport variant, it is this editor’s opinion that
there are significant rulemaking issues, regarding rules for reserve buoyancy, stability, and structural
loads.
In view of the basic nature of these concerns, the small size of the present testcraft, and the very large
jump in scale being envisioned for a sealift ship, ski craft must be considered a far term technology for
sealift. The following comments prepared by Newport Technologies apply:
“Research & development has been ongoing in high speed planing craft with designs
which have been demonstrated to have performance levels above standard planing craft
designs - this work has been going on the part of Quadrimaran and Newport
Technologies and others. Quadrimaran has validated scaling from model scale of 60 ft
to full scale of 100 ft. Newport Technologies has validated math models to a scale of 10
ft / 1000 lbs. Estimates of performance of 10,000 tons at 200 knots have been made by
Newport Technologies and are assumed to have a very large variance. Quadrimaran has
made estimates of a ~7000 t 60 knot ship and is judged to have moderate risk. The risks
are principally associated with the hydrodynamic drag elements friction and spray. The
flat planing surface used by both groups differ in aspect ratios. The Quadrimaran uses
an L/B of under about 10 and Newport Technologies of over about 20. The
Quadrimaran design utilizes aerodynamic lift unlike the Newport Technologies design
which does not. Both designs are observed to be decoupled from the sea waves and are
observed to perform with low accelerations without slamming. Near term extrapolations
of high sped planing hulls to large sealift ships needs to be preceded by continued
research and construction and testing of intermediate size ships.”
31
2.2.1.2.6 Transport Effectiveness State of the Art
Insufficient data exists to present ski craft TF.
2.2.1.3 Hydrofoils
2.2.1.3.1 Historical Origin
The following is excerpted from the February 1985 issue of the Naval Engineer’s Journal:
“Engineers and naval architects have been intrigued with the possibilities envisioned by this concept for
many years. A United States patent for a hydrofoil was defined in the late 1880s, about the same time as
the early airplane and airfoil patents. The earliest record of a successful hydrofoil flight is 1894 when the
Meacham brothersdemonstrated their 14-foot test craft at Chicago, Illinois. This compares with the
Wright brothers' first airplane flight in 1903. The early attempts to exploit the hydrofoil concept were
frustrated by lack of suitable structural materials and power plants. However, advancement in these areas,
much of it stemming from aircraft developments, have permitted development over the past 30-40 years of
the technology necessary to achieve and demonstrate reliable and effective hydrofoil ships for both
military and commercial applications.”
2.2.1.3.2 Dominant Physics
A hydrofoil ship is supported by hydrodynamic lift, generated by circulation around submerged wings.
The particular hydrofoil concept discussed at the workshop - Peter Payne’s DynaFoil™ - has as its
specialty a design intention of recapturing the downwash from one wing, by correct placement of a second
wing. When successful this recapture results in elimination of the induced drag due to lift. The
hydrodynamic drag on the craft is then only the viscous drag on the two wings.
Viscous drag is minimized by minimizing wetted area. But reducing the foil area, for a given craft weight
and speed, requires increasing foil loading. Ordinarily increasing the foil loading would result in a large
drag penalty, as drag due to lift behaves roughly as loading squared.
The DynaFoil™ concept would eliminate this drag, permitting the use of very highly loaded foils, with
small area and thus small frictional drag.
There are many other innovative features of the DyanFoil™ which are described by the inventor below. It
was, however, the particular issue of downwash recovery which has been the most contentious.
Dr. Savitsky offers this comment:
“The hydrofoil concept is based on the speculation that the aft foil of a tandem
foil system will capture the energy related to the induced drag of the forward
foil by working in the upwash if the forward foil. This was an idea postulated
by Dr. Vannevar bush some 40 years ago. (I believe he was the scientific
adviser to President Eisenhower and most influential in establishing maro R&D
programs in the US). It is believed that Bush encouraged a major hydrofoil
program for the US Navy. In any event, extensive model tests and analytical
results failed to demonstrate the beneficial upwash effects postulated by Bish
for realistic configurations. In fact, the aft foil was in a downwash wake and
thus experienced no wake energy recovery. Also, the higher [the] speed, the
less likely is the development of upwash at the rear foil.”
32
2.2.1.3.3 Significant development milestones
Three hydrofoil ships may be used to mark the milestones on the hydrofoil development ground:
USS PLAINVIEW - AGEH 1
Displ 320 LT
LOA 212 ft
Speed 50 knots
Power 30000 HP
Year 1969
Number 1
Overall4 L/D 3.7
USN PHM Class
Displ 239 LT
LOA 145 ft
Speed 48 knots
Power 18000 HP
Year 1977
Number 6
Overall L/D 4.4
Canadian Navy Bras d’Or
Displ 237 LT
LOA 150 ft
Speed 50-60 knots
Power 22000 HP
Year 1969
Number 1
Overall L/D 4.1
The L/Ds of these craft are clearly too low to achieve the required sealift goals. The lift-to-drag ratio must
be increased by a factor of 5 to 10 or more. It is toward exactly this end that the DynaFoil™ project is
aimed.
The following description of the DynaFoil™ was provided by her inventors.
 
4 Includes the effect of propulsive coefficient
33
34
35
36
Current activities
The DynaFoil™ concept referred to above is the work of Payne Associates, Inc. They have produced
several technical papers on the subject5. These papers are in the nature of presentations of the physical
argument. The physical argument is sufficiently cogent to be intriguing. Unfortunately Payne Associates
have not found sponsorship which would allow them to build a conclusive large scale demonstrator. Their
existing demonstrator craft was built specifically to explore the idea of a sprung-foil suspension system,
not the recovery of upwash.
2.2.1.3.4 R&D Needs / Engineering Challenges
Many engineering challenges will be present in the development of a large size DynaFoil™. These will
include:
· Proof of the physics through modelling, both physical and virtual
· Engineering of a large foil retraction system
· Development of a suitable control system
2.2.1.3.5 Transport Effectiveness State of the Art
Insufficient data exists to present DynaFoil™ TF values. Conventional hydrofoil TF’s are already
represented in the dataset.
2.2.2 Aerodynamic Support
2.2.2.1 Aircraft
Aircraft were not discussed at the workshop
2.2.2.2 Ekranoplans
Ekranoplans of the Russian pattern were not discussed at the workshop. The discussions focused on the
WIG-like behavior of certain other concepts, specifically an Ekranocat, Quadrimaran, and Wild Thing.
2.2.2.2.1 Historical Origin
The pure Ekranoplan is a wing-supported vehicle which operates in ground effect. By operating in
ground effect very high lift coefficients may be obtained with very little induced drag. Unfortunately the
enhancement from the ground effect is greatly offset by the typically low aspect ratio of the lifting surface.
Ekranoplans were invented in the (then) Soviet Union and extensively tested, including construction of
large military transports.
 
5 E.g: “On minimizing the Resistance of Hydrofoils” Peter R. Payne, working paper 380-21-R9, available
from Payne Associates, 300 Park Drive, Severna Park, MD 21146-4416.
37
The craft considered at the workshop were of two sorts: A ram/gap multihull, which generates an air
cushion effect through ahead speed (Quadrimaran and Wild Thing) and an aerodynamically shaped
superstructure which generates a small amount of lift to enhance ship performance.
2.2.2.2.2 Dominant Physics
2.2.2.2.3 Significant development milestones
Russian ekranoplan development dates from 1949. A major milestone is the 1965 KM “Caspian Monster”
which attracted the attention of intelligence agencies world wide )see Figure 17). Since that time Russian
designers have fielded about a dozen different types of WIG craft.
Partial aerodynamic support craft of the type considered in the workshop have not received the same level
of centralized attention. However, as commercial ship developers have reached for higher and higher
speeds additional attention has been paid to “aerodynamic alleviation.”
2.2.2.2.4 Current activities
The EkranoCat is an Australian concept6. In this concept a catmaran’s superstructure is faired into an
airfoil shape. This generates a some lift which contributes to the ship’s performance. Because of the end
Figure 17 - The 1965 Soviet Ekranoplan "KM" - Caspian Monster
 
6 “Analysis of the Efficiency of an Ekranocat: A Very High Speed Catamaran with Aerodynamic
Alleviation” Lawrence J. Doctors, International Conference on Wing in Ground Effect Craft (WIGs ’97),
RINA, London UK December 4-5 1997.
38
plate effect of the ship’s sidehulls there may be no induced drag for this component, and thus the L/D of
the house may be significant
However, we see that, even if full stagnation pressure were generated under the cross structure (a Cl of 1)
at 50 knots this would result in a force of 9 lbs per square foot. On a craft the size of the Stena HSS 1500
this represents about 5% of the ship’s weight. While 5% of the ship’s weight is nothing to be sneered at,
it is not a sufficiently large contribution to the lift of the craft to warrant putting the craft in a class by
itself. Indeed, partial air support of this sort should best be considered an enabling technology.
At what speed would the air support become significant? The Aker Finnyards Swath 2000 Project(design) weighs 6000 tons on a “foot print” of 150m x 40m. This yields a weight of 204 psf. This is
consistent with SES of this size, which have cushion heads on the order of 1 meter.
Ram air at stagnation pressure will produce a pressure of 204 psf at a velocity of about 240 knots. At such
speeds full air support becomes possible for surface craft of this size. Indeed, behavior of this sort is seen
in offshore powerboat racing, where ram-air supported tunnel boats become airborne at speeds in the
neighborhood of 200 knots.
The EkranoCat work of Dr. Larry Doctors showed an ability to carry 50% of the weight of a notional craft
at a length Froude number of 2.0. For a 100m catamaran this corresponds to a speed of about 116 knots.
2.2.2.2.5 R&D Needs / Engineering Challenges
No discussions took place regarding the R&D needs of aerodynamically supported craft. The impression
left is that these concepts are nearer to basic research than they are to operational deployment at sealift
sizes.
2.2.2.2.6 Transport Effectiveness State of the Art
Insufficient data exists to present TF for air supported craft.
2.3 Powered Support Ships
2.3.1 Hydrostatic Support
2.3.1.1 Air Cushion Vehicles
2.3.1.1.1 Hovercraft
Pure hovercraft received only passing reference at the workshop. It is interesting to note Dr. Doctors’
FAST ‘97 paper in which he shows that pure hovercraft have the lowest drag of any large fast marine
transport. In the light of this observation, why are there no current advocates of large hovercraft for
sealift? It appears that the complications of the lift system and skirts are the main disadvantage of the
pure hovercraft.
39
2.3.1.1.2 Surface Effect Ships
2.3.1.1.2.1 Historical Origin
Again quoting from the February 1985 Naval Engineer’s Journal:
“Mr. Allen Ford invented the SES, then called a captured air bubble (CAB), in 1960, as a solution to the
problem of excessive lift power required to maintain the air gap of a ground effect machine (GEM) when
traveling over water. This invention has since been developed to obtain a more efficient open-ocean ship.
As compared to an air cushion vehicle (ACV), the SES hull, which pierces the water surface (hence, non-
amphibious), has less air leakage, better longitudinal stability, and an acceptable form for utilizing water
propulsion systems, which, at speeds to about 120 knots, are more efficient than air propulsion. The
shape of the hull with its hydrodynamic stability surfaces can be significantly varied in planform to meet
all design requirements, from small, calm-water "air-lubricated" barges to large ocean-capable ships. The
practical design speed regime of such ships varies from - 15 to + 70 knots.”
2.3.1.1.2.2 Dominant Physics
2.3.1.1.2.3 Significant development milestones
Again quoting from the February 1985 Naval Engineer’s Journal:
“To date. over 460 SESs have been developed and are operational throughout the world. The U.S. Navy's
interest has been focused upon the technology required to optimize these ships and demonstrating this
technology by the development of many testcraft prior to their introduction as mature mission systems in
the fleet.
“Although the top speed of most operational SESs is below 40 knots, the historical thrust was to develop a
80-100 knot capability. This was initiated in 1969 with the award of construction contracts to Aerojet
General for the SES-100A and to Bell Aerospace for the SES-100B testcraft. Both of these 100-ton
testcraft were extensively operated to successfully validate the architectural and engineering technologies
developed in parallel with their design and subsequent modifications. Most noteworthy in performance.
the SES-100B established a sustained speed record of 91.9 knots in a slight chop and operated at 35 knots
in 6-8 feet waves. The SES-100A was modified in 1978 to become a 1/4-scale version of the then on
going U.S. Navy 3000-ton, 80-knot prototype (called the 3K SES) contract design and construction
program. Unfortunately for the advancement of modern ships, the 3K SES program was terminated on 7
December 1979, just three weeks prior to the initiation of hull construction. This singular termination
based mainly on the lack of a military mission for this large prototype caused the total frustration of
Admiral Elmo Zumwalt's thrust, as Chief of Naval Operations (1970-1974), for a "100-knot Navy."
However, a political decision cannot alter physical laws, and an extensive high performance and SES data
base has been developed and continues to be expanded and applied towards more modern surface ships.”
2.3.1.1.2.4 Current activities
Three major activities were discussed at the workshop. These were the Ingalls Surface Effect Vehicle
point design, the Japanese TSL-A, and the ongoing development of the seal-less SES by Harley
Shipbuilding. These are addressed separately below:
a) Ingalls SEV
The Ingalls SEV has been much discussed and published. Significant milestone publications include the
Naval Engineers Journal, May 1989.
40
Ingalls produced the attached matrix of calculations showing the predicted performance for the SEV at a
variety of loading and machinery options. This data is consistent with other SES data. No participant at
the workshop suggested, either publicly or privately to the chairman, that the Ingalls data was
unbelievable.
c) Techno Super Liner
The TechnoSuper Liner program was a Japanese government funded development program. Over a
period of about 4 years the team researched several hull forms for development of a ship with the
following requirements:
Cargo 1000 tonnes
Speed 50 knots
Range 500 n.mi
The team centered on development of SES and Hydrofoil options. Two testcraft were built. One was a
hydrofoil of 15-20m length. The second was a 70m SES. It is clear from the allocation of prototyping
funds that the SES was perceived to be a better solution to the design challenge.
The 70m SES, named Hisho, has been built and has demonstrated carriage of cargo at speeds up to 54
knots. Hisho is depicted in Figure 18 below.
Figure 18 - The 70m TechnoSuper Liner demonstrator "Hisho"
b) Harley SES
One perceived problem with large SES is the existence of the fabric seals. This was identified in 1989 as
a major development issue. Harley Shipbuilding Corporation has been developing an SES concept that
has no seals. This craft is depicted in the Harley patent document illustration, reproduced as Figure 19
below.
41
Figure 19 - The patent illustration for the Harley SES
The craft is, obviously, a type of SES Catamaran. Each hull contains an air cushion. Because of the
catamaran configuration the air cushions are of high L/B and thus do not show a pronounced drag hump.
The concept uses a V-shaped planing bow in lieu of a bow skirt. The air is admitted aft of this bow. The
role of the stern skirt is played by a gentle decrease in the inverse deadrise of the cushion area. Harley
shipbuilding provided the following summary of their concept:
“What is unique about the Harley SES, is that it is the first to successfully
combine Dynamic Lift and Air Cushion Lift, and the result is far more lift than
just pure air cushion lift. This is of great significance. Also added to this is the
Catamaran Lift from the air forced between the hulls at speed. The
combination of these three lifting elements do connect to provide great lift to
the vessel, particularly as speed increases and load increases.
“Also this design gives much structural friendliness; it allows lighter structure
from structurally friendly design including shorter span between hulls, and
measured low loads from softer ride; and the lighter high-strength composites,
further combine to allow much more weight to be allowed to cargo.
“Model Testing has indicated that a 730’ Harley SES could carry as much as
20,000 tonsand cruise at 50+ knots. The model testing has also indicated that
80-100 Knot continuous can be achieved carrying 5,000 to 10,000 tons.
42
“The elimination the flexible seals can solve a long list of problems that have
characterized previous SESs and other air cushioned vessels: among these
problems are frequent seal breakage, the high cost of the seals, the poor ride
quality caused by the seals, the high hump drag inherent in traditional SESs,
the center of gravity sensitivity, the limited sea state capabilities, the very high
blower requirements, the limited containment of the air cushion (typically with
large losses and variations due to the flexible seals), the high structural loads
the traditional conventional SESs typically have, and most significantly, the
limited weight carrying ability universally demonstrated in all SESs and air
cushioned vessels with flexible seals.
“The Harley tests have indicated very significant gains in weight carrying
abilities over conventional SES and air cushioned designs with its combination
of dynamic planing lift and air cushioned lift and catamaran lift. Further
testing of Harley’s new 55' SES soon to be in the water will provide further
information and further confirmation of the very promising results
demonstrated in their 7½’ model testing programs.
“The Harley 26'xl0’ SES with the single 115 hp outboard has demonstrated 52
knots on the GPS. This was shown on video tape during the hull forms
workshop. Compared to modem catamaran design, this has shown dramatic
improvement as compared to current state of the art catamarans of this size.
The Navy XR-3 25 foot SES reached 25 knots with twin 50 hp outboards,
similar power to Harley's 26 foot SES.
“Harley Shipbuilding also claims that highly significant weight savings on full
sized ships (400’ - 800’) can be achieved by the use of most modern composite
technologies, not heavily used in the current marine industry in any sector.
Aircraft composite technologies have gone much further than marine
demonstrations of composite technologies, and Harley has used its aircraft
background to apply some of its aircraft composite expertise to high speed
marine vessels, and believes there is much weight to be saved, and therefore
much more weight to be carried in cargo, with the proper application of the
ever improving and well proven aircraft composite technologies.
“The Harley design through planing dynamic lift and air cushioned lift does get
nearly the entire vessel out of the water, and this is certainly a key element in
highly significant drag reductions and load carrying abilities.
“In Harley Shipbuilding's model test program, models were tested against
comparative V-hulls of same length and weight, twin Hulls, Catamarans, Air
Slip-Stream Cat designs, SESs, and other skirt-free SES designs (ie. Air Ride
Craft); and Harley's tests, particularly when both vessels were given significant
loads to carry (not lightship conditions), efficiencies of between 2 times and in
some cases up to 4 times were universally observed in the model testing. The
minimum improvement was 2 times the efficiency of the next closest test model
in the comparative testing in these conditions.
“Harley points out that the only really high speed ships built to date have been
SESs, i.e. theSES-100A at 80 knots, and the SES-100B at 92knots. Each of
these were quite heavy ships for their length, particularly by today's standards.
No other designs for real ships have produced these speeds on real ships, to our
knowledge. Harley believes that only some sort of air cushioned ship can reach
these speeds and carry any significant load. Getting the vessel out of the water
43
as much as possible, but still maintaining the higher lift pressure that can be
generated between the vessel and the water by maintaining contact, yet with air
pressurization, is where the greatest lifts can be achieved.”
Harley Shipbuilding is not the only inventor of the skirt-free SES idea. In the USA Don Burg’s Air Ride
craft are very similar, and the same concept has been developed and tested in Russia. A monohull using
this concept “Linda” has been built, and several catamaran versions have been designed. Figure 20
depicts the Linda craft (apologies for the poor quality of the photograph.)
Figure 20 - Russian Skirt-less SES Monohull "Linda"
2.3.1.1.2.5 R&D Needs / Engineering Challenges
The hull design of the skirt-less SES has not been optimized.
2.3.1.1.2.6 Transport Effectiveness State of the Art
Data has been added to the transport factor data file to represent the SES craft. This includes multiple
datapoints on the Ingalls SEV and the one known datapoint for the Harley SES. The data is presented in
Table 2, below. A plot of Transport Factor versus speed is given in Figure 21, TF versus Volume Froude
Number is given in Figure 22
44
Table 3 - TF Data for Surface Effect vessels
Ship or Concept
(all are designs except for Harley)
Speed
(knots)
Power
(SHP)
Range
(n.mi)
Payload
(LT)
Displacement
(LT)
TF
GT 185 85 35000 4500 0 440 7.35
SEV - WITH 8 LM 2500+ TURBINES 52 381800 12,000 1,735 28,465 26.65
SEV - WITH 8 LM 2500+ TURBINES 57 381800 12,000 34 25,399 26.07
SEV - WITH 8 LM 2500+ TURBINES 37 381800 8,000 17,202 42,951 28.61
SEV - WITH 8 LM 2500+ TURBINES 63 381800 8,000 176 19,909 22.58
SEV - WITH 8 LM 2500+ TURBINES 37 381800 4,000 21,177 39,638 26.40
SEV - WITH 8 LM 2500+ TURBINES 69 381800 4,000 27 15,107 18.77
SEV - WITH 8 LM 2500+ TURBINES 37 381800 0 25,153 36,325 24.20
SEV - WITH 8 LM 2500+ TURBINES 74 381800 0 68 11,240 14.98
SEV - WITH 8 LM 6000 TURBINES 70 560,304 12,000 2,936 29906.2 25.68
SEV - WITH 8 LM 6000 TURBINES 78 560,304 12,000 36 25385.9 24.29
SEV - WITH 8 LM 6000 TURBINES 48 560,304 8,000 17,279 43810.3 25.80
SEV - WITH 8 LM 6000 TURBINES 85 560,304 8,000 44 19889.5 20.74
SEV - WITH 8 LM 6000 TURBINES 48 560,304 4,000 21,468 40319.1 23.74
SEV - WITH 8 LM 6000 TURBINES 91 560,304 4,000 173 15395.2 17.19
SEV - WITH 8 LM 6000 TURBINES 48 560,304 0 25,657 36829 21.69
SEV - WITH 8 LM 6000 TURBINES 97 560,304 0 82 11254 13.39
SEV - WITH 8 GE 90 TURBINES 101 1,430,670 7,000 3,781 30784.2 14.94
SEV - WITH 8 GE 90 TURBINES 117 1,430,670 7,000 172 25620.9 14.40
SEV - WITH 8 GE 90 TURBINES 74 1,430,670 5,000 17,134 43740.1 15.55
SEV - WITH 8 GE 90 TURBINES 119 1,430,670 5,000 -22 20747.5 11.86
SEV - WITH 8 GE 90 TURBINES 74 1,430,670 3,000 20,502 40934.9 14.55
SEV - WITH 8 GE 90 TURBINES 124 1,430,670 3,000 216 16914.4 10.08
SEV - WITH 8 GE 90 TURBINES 74 1,430,670 0 25,553 36725 13.06
SEV - WITH 8 GE 90 TURBINES 132 1,430,670 0 254 11426 7.25
Harley SES (built) 43 115 1.5625 4.06
45
ACVs & SES
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
0 50 100 150 200 250
SPEED (knots)
T
F
Figure 21 - Transport factor of SES & ACVs, dimensional speeds. Filled spots designate ships which
have been built. Open spots designate designs.
ACVs & SES
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
0 1 2 3 4 5 6 7 8 9 10
Volume Froude Number
T
F
Figure 22 - Transport Factor for ACVs and SESs, non-dimensional speed Filled spots designate
ships which have been built. Open spots designate designs.
46
2.3.2 Aerostatic Support
Aerostatically supported vehicles were not discussed at the workshop.
47
3. Propulsors
3.1 Waterjets
3.1.1 Dominant Physics
See Black et al, Appendix 6.3.
3.1.2 State of Development
Commercial off-the-shelf waterjets are available up to 60,000 SHP, designed for operation at speed of 30
to 60 knots. Larger units are planned.
The performance of modern waterjets is depicted in Figure 23. That figure presents bands of performance
based on actual operatingexperience. The consensus of the workshop committee was that the figure was
accurate from own experience.
The figure only presents data to 60 knots. INCAT have stated that waterjet propulsion is viable to 80
knots, with OPC of about 0.60 at that speed.
It is important to note the definition of overall propulsive coefficient, as used in the figure. This is the
ratio of bare hull EHP to trials SHP. As such it includes appendage drag as a component of OPC. This is
because different propulsors have different appendage suites and it seems appropriate to allocate the
appendages to the propulsor - to make the propulsor pay for its own appendages.
3.1.3 Current Activities & R+D Needs
The current focus of commercial development is toward increasing power. The “conventional” path for
increasing power has been to make ever larger jet units. This, however, is running against geometric
constraints in the latest generation of fast ships. Ship designers are asking for large powers on small
transoms, requiring the development of units with ever higher power/diameter ratios.
Manufacturers are addressing this need by investigating various combinations of multi-stage, axial, and
inducer-type pumps.
3.1.4 Propulsive Efficiency State of the Art
The state of the art for large waterjets on high speed ships is depicted above in Figure [[]]. As shown, the
propulsive efficiency is 0.70 to 0.75 in the speed range 40 to 60 knots.
48
Figure 23 - State of the Art Performance for Waterjets and other Propulsors
3.2 Propellers
3.2.1 Fully Wetted Propellers
Fully wetted propellers did not receive much discussion at the workshop. The consensus was that their
performance is well understood and documented. Tacitly the attendees endorsed Figure 23 as describing
the performance of Fully Wetted Propellers.
3.2.2 Ventilated propellers
Discussion of ventilated propellers centered on debates and anecdotes of performance values. The
consensus was again to endorse Figure 23 as descriptive.
49
3.2.2.1 Dominant Physics
3.2.2.2 State of Development
3.2.2.3 Current Activities & R+D Needs
3.2.2.4 Propulsive Efficiency State of the Art
Surface propeller performance is shown in Figure 23. Again, that figure is truncated at 60 knots. INCAT
have provided the opinion that surface drives at 80 knots are off-the-shelf technology up to 22 MW per
shaft, with a resulting propeller diameter of about 3 meters.
50
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51
4. Centers of Activity in High Speed Ships
How does one stay abreast of the developments in high speed ship technology? The following list presents
three major recurring conference which are attended by, indeed in some cases organized by, workshop
participants.
4.1 Major Conferences and Shows
4.1.1 Fast Ferry International
Fast Ferry International magazine holds an annual conference dealing specifically in technology and
operational issues of fast ferries and other fast ships. Fast Ferry International magazine was once
Hovercraft Magazine. The magazine has shown a tendency to evolve as the fast ship industry evolves.
Thus, as most fast ships today are ferries, sot he magazine treats primarily of ferries.
The result of this desirable chameleon behavior is to suggest that the Fast Ferry conference will remain a
center of discussion for fast ships, whatever their vocation.
Fast Ferry 1998 is to be held in Copenhagen 24-26 February 1998. For more information see
www.fastferry.co.uk/conference.html.
4.1.2 FAST
The FAST series of conference proceedings is one of the major reference works in the technology of fast
ships. Held every two years since 1991 (hence FAST 91, FAST 93, FAST 95, and FAST 97). The
proceedings may be ordered from:
Fast International Foundation
Mr. Kjell Holden, Director
Marintek
Norwegian Maritime Technology Research Institute
Otto Nielsensv. 10
POBox 4125 Valentinlyst
Trondheim N-7002 NORWAY
tel: +47-73-59-55-00
fax: +47-73-59-58-70
e-mail: kjell.holden@marintek.sintef.no
FAST 99 will be held in Seattle Washington August/September 1999. See:
www.baird.com.au/fast/index.htm
4.1.3 HIPER
HIPER 99 is a new conference scheduled for 24-26 February 199, in Zevenwacht South Africa. For more
information see www1.sun.ac.za/local/academic/fak_ing/meg_ing/HIPER_99/HIPER_99.html.
52
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53
5. Enabling Technologies
Enabling technologies are those which contribute to the success of the advanced craft. For example,
lightweight structure is of benefit to all of the various craft. This section provides a brief overview of the
different enabling technologies and their states of development. This section may be considered to be
orthogonal to the “Enabling Technologies” entries specific to each of the vehicle types.
5.1 Hydrodynamics
Resistance - Air Lubrication: Much of the research on high speed ships has been directed at reducing
wave drag. As a result many of the most promising high speed concepts (videlicet the SES and the
Slender hull) find themselves dominated by frictional drag.
Workshop participants spoke of no successful large scale friction reduction techniques. Many have been
explored, such as latorre’s “Ship Hull Drag Reduction Using Bottom Air Injection”7 but there are few if
any operational ships with such systems
Successful friction reduction would bear much fruit for high speed ships.
Resistance - High Rn Friction
Resistance - Correlation allowance: For example, at 60 knots for a length of 200m the Reynold’s number
is around 6x10^9. The ITTC friction line predicts Cf=0.00124, while a typical Ca is 0.0004. Hence a
perfectly smooth surface would save 25% of frictional resistance.
5.2 Structure
5.3 Propulsion
5.4 Electrical and Auxiliary Machinery
5.5 Command and Control
Weather routing
Collision Avoidance
 
7 Ocean Engineering, volume 24, No 2, pp 161-175, 1997
54
55
6. Appendices
6.1 Membership of subgroup “Hullforms, Hydrodynamics, and
Propulsors”
NAME COMPANY ADDRESS PHONE/FAX/EMAIL
Allison, John Band Lavis and
Associates
900 Ritchie Highway Severna
Park, MD 21146
410-544-2800
202-262-1030
410-647-3411 (fax)
Black, Dr. Scott D. NSWCCD, Code
5400
9500 MacArthur BoulevardWest
Bethesda, MD 20817-5700
301-227-4304
black@oasys.dt.navy.mil
Blount, Don Donald L. Blount &
Assoc.
2550 Ellsmere Ave., Suite K
Norfolk, VA 23513
757-857-1943 757-857-
4160
73430.2366@compuserv
e.com
Bowden, John Ingalls ShipbuildingMS 1090-11 P.O. Box
149Pascagoula, MS 39568-0149
601-935-6832601-935-
6838 (fax)
bowdenjo@ingalls.com
Clifford, Bob INCAT 18 Bender Drive Moonah
Tasmania 7009 Australia
61 (0) 3 6273 0677 61
(0) 3 6273 0932 (fax)
rclifford@incat.co.au
Conradi, Trond Quadramaran
International
263 McLaws Circle Williamsburg,
VA 23187-1959
804-220-2355 804-253-
8110 (fax)
quad@bellatlantic.net
Daskovsky, Mark Payne Associates 300 Park Drive Severna Park, MD
21146-4416
410-647-4943
daskovsky@aol.com
Davis, Michael J.
**CO-CHAIR
NSWCCD, Code
5500
9500 MacArthur Boulevard West
Bethesda, MD 20817-5700
301-227-1228
mdavis@dt.navy.mil
Doctors, Prof. Larry Univ. of New South
Wales
Sydney, NSW 2052, Australia +61 2 9385 4098
+61 2 9663 1222 (fax)
l.doctors@unsw.edu.au
Enlund, Hakan Aker Finnyards P.O. Box 139FIN-26101 Rauma
FINLAND
358 2 83 611 or 358 2
836 4178358 2 836 2366
(fax)
hakan.enlund@finnyards
.fi
Fung, Siu NSWCCD 9500 MacArthur Boulevard
West Bethesda, MD 20817-5700
Giles, David L. Fastship Atlantic 123 Chestnut Street, Suite
204Philadelphia, PA 19106
215-574-1770
215-574-1775 (fax)
56
Goubault, Phillipe Band Lavis and
Associates
900 Ritchie HighwaySeverna Park,
MD 21146
410-544-2800202-261-