Sea vessel

A water vessel comprising a hull, at least one retractable hydrofoil apparatus configured for disposition in an extended orientation for vessel operation in a hydrofoil mode and for disposition in a retracted orientation for vessel operation in an undersea mode and propulsion apparatus providing propulsion of the vessel in both the undersea mode and the hydrofoil mode.

FIELD OF THE INVENTION 
The present invention relates to watercraft generally and more particularly 
to watercraft having foils. 
BACKGROUND OF THE INVENTION 
Various types of watercraft having foils are known in the art. There is 
shown in U.S. Pat. No. 3,357,389 a hydrofoil system and method of forming 
lift foils for use therein which is suitable for use with a surface craft. 
U.S. Pat. No. 3,789,789 describes a hydrofoil sailing craft which has 
controllable and retractable hydrofoils. 
U.S. Pat. No. 4,715,304 to the present inventor describes hydrofoil 
apparatus comprising a hull, a pair of hydrofoils, each including first 
and second planar surface portions, pivotal mounting apparatus for 
mounting the pair hydrofoils onto the hull, and apparatus for selectably 
and variably determining the dihedral angle between the first and second 
planar surface portions. 
SUMMARY OF THE INVENTION 
The present invention seeks to provide a vessel, which has the capability 
of undersea, planing, hydrofoil and combined planing and hydrofoil 
operation, all at relatively high efficiency. 
There is thus provided in accordance with a preferred embodiment of the 
present invention a water vessel comprising a hull, at least one 
retractable hydrofoil apparatus configured for disposition in an extended 
orientation for vessel operation in a hydrofoil mode and for disposition 
in a retracted orientation for vessel operation in an undersea mode and 
propulsion apparatus providing propulsion of the vessel in both the 
undersea mode and the hydrofoil mode. 
There is thus provided in accordance with an alternative embodiment of the 
present invention a water vessel comprising a hull, at least one 
retractable hydrofoil apparatus configured for disposition in an extended 
orientation for vessel operation in a hydrofoil mode and for disposition 
in a retracted orientation for vessel operation in a docking mode and 
propulsion apparatus providing propulsion of the vessel in both the 
docking mode and the hydrofoil mode. 
Additionally in accordance with an embodiment of the invention the 
retractable hydrofoil apparatus is also configured for disposition in a 
planing orientation intermediate the extended orientation and the 
retracted orientation for vessel operation in a planing mode. 
Additionally in accordance with an embodiment of the invention the 
retractable hydrofoil apparatus comprises first and second planar 
surfaces. The retractable hydrofoil apparatus is also configured, in 
accordance with a preferred embodiment of the present invention, for 
disposition in an undersea orientation intermediate the extended 
orientation and the retracted orientation whereby the dihedral angle 
between the first and second planar is controlled to provide roll control 
for vessel operation in the undersea mode. 
Further in accordance with a preferred embodiment of the invention, the 
propulsion apparatus comprises first propulsion apparatus for propulsion 
of the vessel in the hydrofoil mode and second apparatus for propulsion of 
the vessel in the undersea mode. 
Additionally in accordance with an embodiment of the invention, the first 
apparatus is retractable into the hull. 
In accordance with an alternative embodiment of the invention, the 
propulsion apparatus comprises water jet propulsion apparatus which is 
operative to provide propulsion for the vessel in both the hydrofoil mode 
and the undersea mode up to a predetermined depth. 
Further in accordance with an embodiment of the invention, there is 
provided in association with the hull fluid inflatable hull configuring 
apparatus for expanding the envelope of the hull for undersea operation. 
Still further in accordance with a preferred embodiment of the present 
invention, the water vessel additionally comprises a containerized payload 
module shaped to match the shape of the hull of the vessel. 
Moreover, in accordance with a preferred embodiment of the present 
invention, the water vessel additionally comprises a retractable mast for 
air intake and exhaust during a partially submerged operation and for 
supporting detectors for collecting information about the region in which 
the vessel currently operates. 
Finally, in accordance with a preferred embodiment of the present 
invention, the second propulsion apparatus comprises a fishtail apparatus 
for undulatingly producing propulsion. The fishtail apparatus is supported 
by eddy amplifying jets for increasing the propulsion produced.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
Reference is now made to FIGS. 1A, 1B, 3A, 3B, 3C, 5, 7A and 7B which 
pictorially illustrate a sea craft which has the capability of undersea, 
planing and hydrofoil operation, all at relatively high efficiency, 
constructed and operative in accordance with a preferred embodiment of the 
present invention. Reference is also made to FIGS. 2A and 2B, 4A and 4B, 
6A and 6B, and 8A and 8B. FIGS. 2A, 4A, 6A and 8A are bottom views and 
FIGS. 2B, 4B, 6B and 8B are side views of FIGS. 1A, 3A, 5 and 7A, 
respectively. 
As shown in FIG. 1A, the sea craft comprises a cigarette shaped hull 10, 
retractable forward foils 12 for lifting the hull 10 partially above the 
water line, denoted WL, and a retractable rear foil 14 for propelling the 
sea craft through the water. The sea craft of the present invention 
typically also comprises a retractable mast 16 for holding detector 
devices, such as radar, on a detector dish 18, and a cargo container 20, 
denoted by a dark line on the hull 10, for storing cargo to be shipped 
from one location to another. 
Cargo container 20 is typically an unloadable container designed to match 
the streamlined shape of hull 10. A multiplicity of cargo containers 20 
can be built for performing a multiplicity of operations, such as for 
storing ore, for storing general cargo or for storing refrigerated cargo. 
The cargo container 20 appropriate for a given trip is loaded into the 
hull 10; the remaining cargo containers 20 typically stay in port. Thus, 
one craft may perform many differing operations. 
It will be understood that the cargo container 20 can also be at least 
partially utilized as quarters for the crew of the craft. The quarters can 
be wet accommodations, where the crew must wear scuba gear, or they can be 
dry accommodations where scuba gear is not necessary. 
FIG. 1A illustrates the sea craft of the present invention in a hydrofoil 
mode orientation with the forward foils 12 extended generally diagonally 
outwards and the rear foil 14 and the mast 16 extended vertically. 
In accordance with a preferred embodiment of the present invention, the 
forward foils 12 are each typically comprised of a strut 22 for providing 
both lift to the craft and structural support to a tip 24 whose dihedral 
angle relative to strut 22 is changeable. 
Tips 24 are the main lifting surfaces of the craft. They are typically 
extended such that they are generally parallel to the water surface. Since 
any lifting element provides lift perpendicular to its surface, the tips 
24 provide lift generally perpendicular to the surface of the water and 
thus provide the sea craft with a significant amount of lift. 
Due to the angle at which the struts 22 pierce the surface of the water, 
the portions of the struts 22 below the surface of the water also provide 
the craft with some lift. Additionally, since the struts 22 are surface 
piercing elements, they act as foil stabilizers for stabilizing the craft 
in rough weather. The deeper the struts 22 are submerged below the water, 
the more lift they provide. Concurrently, the additional lift pushes the 
struts 22 out of the water. Thus, the craft tends to a stable location in 
both the transverse and longitudinal directions. The stability in the 
longitudinal direction is produced due to the fact that, in accordance 
with a preferred embodiment of the present invention, the forward foils 12 
are located close to and forward of the center of gravity of the craft. 
It will be appreciated that, during rough weather, the foils 12 help to 
maintain the craft in a stable position as well as to dampen the craft 
motion. When a large wave hits the craft, it meets the bow first, creating 
a pitching moment on the As the wave reaches the middle of the craft, it 
produces an upward force on the craft, known as a heave. Since the 
entirely of the tips 24 and portions of the struts 22 are submerged in the 
water and are thus unable to heave instantaneously, the heave motion is 
dampened. However, the pitching moment causes an increase in the angle of 
attack of the struts 22 which increases the lift on the craft and thus, 
heaves the craft somewhat. The following large wave will have a lesser 
effect since the craft will be higher above the water than it was for the 
first wave. Thus, the effect of the foils 12 is to smooth the reaction of 
the craft to large waves. This is advantageous over planing hulls. 
It will be appreciated that the structure of the forward foils has 
advantages over prior aft vertical struts in that the angled forward foils 
provide some lift forces. 
It will also be appreciated that the forward foils 12 of the present 
invention provide, while the craft is in motion, a relatively smooth 
transition from a fully retracted orientation, described in mope detail 
hereinbelow and with reference to FIGS. 5 and 7A, to the hydrofoil mode 
orientation shown in FIG. 1A. Prior art vertical struts typically can only 
be folded into lifting location while the craft has close to zero speed. 
The transition from the fully retracted orientation to the hydrofoil 
orientation is performed as follows. While the craft is docked and at any 
time that it is moving on the surface of the water without utilizing the 
forward foils 12, the craft operates as a displacement hull and therefore, 
only moves at relatively slow speeds. Preparatory to or simultaneously 
with the extension of the foils 12, the speed is increased. The foils 12 
are smoothly extended in a continuous motion from their fully retracted 
orientation to their fully extended orientation and the speed is increased 
in proportion to the amount of the extension. 
It will be appreciated that once the foils 12 are partially extended, the 
craft begins to operate in a planing mode, to be described in more detail, 
hereinbelow and with reference to FIGS. 3A, 3B and 3C. Since a planing 
craft can operate faster than a displacement hull, the speed of the craft 
is accordingly increased. At this stage, the tips 24 remain in the same 
plane as the struts 22. 
As the craft increases speed, the foils 12 are moved to their fully 
extended position, with the tips 24 still in the same plane as the struts 
22. At this stage, the full surface of the foils 12 provides lift and the 
hull 10 lifts partially out of the water. For light craft, the hull 10 
might lift completely out the water. 
At the end of the transition, the dihedral angle between the tips 24 and 
the struts 22 is changed thereby allowing the tips 24 to operate as 
relatively efficient fully submerged foils. 
FIGS. 3A, 3B and 3C illustrate the craft in a planing mode where, as seen 
in FIG. 3C, most of the hull 10 is above the water and only the lower 
surface of the foils 12 are in contact with the flow of the wager. FIG. 3B 
illustrates the planing mode for a craft which is heavier than that of 
FIG. 3A such that the partially extended forward foils 12 are partially 
covered by the flowing water. FIG. 3A illustrates the planing mode for a 
craft heavier than that of FIG. 3B. In FIG. 3A, the water flows generally 
above most of the surface of foils 12 as well as below the foils 12. 
For the planing mode, the forward foils 112 are partially extended from 
their retracted orientation to an intermediate planing orientation. The 
tips 24 are in the same plane as the struts 22 and the entirety of each 
forward foil 12 forms a planing surface. Additional planing surfaces are 
provided by the shape of the bottom side of the hull 10, described in 
detail hereinbelow and with reference to FIGS. 12A, 12B, 12C and 12D. 
In the planing mode, the rear foil 14 and the mast are fully extended. In 
accordance with an alternative embodiment of the planing mode of the 
present invention, the rear foil 14 is partially retracted. 
In the planing mode of FIG. 3A, the water flows on the majority of the 
upper surface of the forward foils 12, as well as underneath the foils 12. 
Thus, the foils operate as long chord foils. In the planing mode of FIG. 
3B, the water flows partially on the upper surface of the foils 12. The 
portion of the foils 12 thus covered with water operate as long chord 
foils and the remaining portions operate as planing surfaces. In the 
planing mode of FIG. 3C, the water flows only on the underside of the 
foils 12 and thus, the foils 12 operate as planing surfaces. 
FIG. 5 illustrates a partially submerged mode where the mast 16 is 
partially submerged. The forward foils 12 are fully retracted but the mast 
16 and the rear foil 14 are fully extended. In this mode, the craft can be 
mostly hidden and can utilize the detectors on detector dish 18 to detect 
other crafts in its vicinity. 
In the above water line modes of planing and hydrofoil, as shown in FIGS. 
1A and 3, the power for propulsion is provided by a first propulsion 
system comprising turbines 25 (FIG. 6B). Air is provided to turbines 25 
via air intake inlets 26, located on both sides of an upper fin 28 (only 
one is visible in FIG. 5). In the partially submerged mode of FIG. 5, air 
intake inlets 26 are closed and air is taken in and exhaust is removed 
through air inlet 40 and exhaust outlet 42 (FIG. 6B), respectively, 
located in the mast 16. Exhaust can, alternatively, be removed through the 
water. 
As in the planing mode of FIG. 3, the rear foil 14 and the mast 16 are 
fully extended. 
FIGS. 7A and 7B illustrate the craft in two undersea modes. In the mode of 
FIG. 7A, the forward foils 12, the rear foil 14 and the mast 16 are fully 
retracted and air inlets 26 are closed. The resultant craft is streamlined 
for low resistance travel undersea. Propulsion is provided by a second 
propulsion system comprising an electric motor 44 (FIG. 8B) typically 
operating in conjunction with a propeller 46 (FIG. 8B), such as a fixed or 
a variable pitch propeller. 
Pitch steering is provided by two undersea control surfaces 48, attached to 
side fins 49, and by an undersea rudder 50. Surfaces 48 provide roll and 
pitch movement and rudder 50 provides directional steering. 
In the alternative undersea mode of FIG. 7B, the forward foils 12 are 
partially extended while the rear foil 14 and the mast 16 are fully 
retracted and air inlets 26 are closed. The forward foils 12 are partially 
extended to the point that the tips 24 are completely out of the hull and 
can rotate with respect to the struts 22. In this manner, the tips 24 can 
act as additional control surfaces. 
In accordance with a preferred embodiment of the present invention, 
propulsion and steering for the hydrofoil, planing, and partially 
submerged modes are provided by the rear foil 14. The rear foil 14 
typically comprises two counter-rotating propellers 52 for propelling the 
sea craft and a rear strut 54 to which is attached a rudder 56 for 
steering and foils 58 for providing lift to the aft portion of the craft. 
Control surfaces 60 (FIG. 2A), attached to foils 58, provide pitch and 
roll control to the craft. 
In accordance with an alternative embodiment of the present invention, as 
shown in FIG. 1B, propellers 52 of the read foil 14 are replaced by a 
water jet 61, such as Jacuzzi jets. 
As mentioned hereinabove, FIGS. 2A and 2B show the top and bottom views of 
the craft in the hydrofoil mode orientation. The two propulsion systems of 
the craft can be clearly seen in FIG. 2B. FIGS. 4A, 4B, 6A, 6B, 8A and 8B 
show the craft with the mast 16, reap foil 14 and the forward foils 12 in 
their various positions. It will be noted that FIG. 8A shows a cover 62 
over the retracted rear foil 14 and FIG. 8B shows a cover 64 over 
retracted mast 16. Covers 62 and 64 are typically sliding doors and are 
necessary for keeping the water out of the craft when it is in an undersea 
mode. Rubber gaskets 66 which fill an opening 67 in which are located 
Forward foils 12 serve the same purpose. 
Referring back to FIGS. 2A and 2B, it will be seen that it is possible to 
bank the craft by slightly pivoting forwards one forward Foil 12 from its 
fully extended position and by slightly pivoting backwards the second 
forward foil 12 from its fully extended position. Because the forward 
foils 12 are angled with respect to the hull 10 and because they retract 
and extend via rotation, as shown in more detail hereinbelow and with 
reference to FIG. 10, the angle of attack of the forward foils 12 are 
respectively increased or decreased as they are extended or retracted. 
Thus, a banking effect is produced in the craft when the Forward foils 12 
are not in the same location with respect to the hull. For example, in 
FIG. 2A, the port Foil 12 is slightly extended and the starboard foil 12 
is slightly retracted, thus banking the craft to the right. The increase 
in angle of attack in the starboard foil 12 is noted on FIG. 2B as sa. 
Reference is now made to FIGS. 9, 10, 11A and 11B. It will be appreciated 
that the banking described hereinabove, requires that each forward foil 12 
be individually operable. This requirement is fulfilled, as shown in FIG. 
9, with two motors 70, one for each forward foil 12. 
Each motor 70 rotates a beveled gear 72 which, accordingly, rolls along a 
curved toothed track 74 (FIG. 10) embedded into each of the forward foils 
12, thereby rotating each foil 12 about a diagonal axis 83. The rotation 
of each foil 12 produces either retraction or extension of the foil 12 
from the hull 10. 
Below each foil 12 is a counter support system 76 for supporting the foil 
12 and for maintaining the tolerance between the beveled gear 72 and the 
teeth of the track 74. The counter support system 76 comprises a recess 81 
located directly below the track 74 on the underside of the foil 12 and 
bearings 82 fixed to the hull 10 inside a seat 80 and directed to the 
recess 81. Recess 81 is in the shape of track 74. 
As the foil 12 rotates in accordance with the rotation of the beveled gear 
72, the bearings 82 move inside recess 80 and keep the foil snug to the 
beveled gear 72. Thus, the counter support system ensures that the foil 12 
follows track 74. 
It will be appreciated that the counter support system 76 is necessary to 
reduce the deflection of foil 12 due to the levered force of the water on 
the tip 24 which can cause the curved track 74 not to properly engage the 
beveled gear 72. 
FIG. 10 shows one foil 12 as it rotates in accordance with the movement of 
the gear 72 about an axis 84. In location A, the foil 12, marked with a 
solid line, is in an extended position typical for the hydrofoil mode. The 
tip 24 is bent at a dihedral angle B (FIG. 11) from the line defined by 
the strut 22. When the foil 12 is retracted, the tip 24 is first 
straightened to the location shown in locations B and C. Location B is an 
intermediate location, somewhat further out than that for the planing mode 
of operation of the craft, and location C is a fully retracted location, 
typical for the undersea mode. 
The angle B, as mentioned hereinabove, enables the tip 24 to be generally 
parallel to the surface of the water. In accordance with a preferred 
embodiment of the present invention, during banking, the angle B of each 
tip 24 is set to a different value so as to maintain proper lift during 
the banking maneuver. For the forwardly pivoted foil 12, angle B is 
increased and for the backwardly pivoted foil, B is decreased. 
Additionally, the angle B is changed during the banking period. Typically, 
an initial value of B will be chosen as the craft begins the banking 
maneuver. The value of B will be continuously changed throughout the 
maneuver until the craft pulls out of the maneuver. 
The angle B is typically achieved via the action of hydraulic pistons 84 
(FIG. 10) attached to strut 22 and eccentrically operating on a hinge 86. 
FIGS. 11A and 11B show the operation of one of the pistons 84. A rod 88 of 
the piston 84 is attached to tip 24 at a location below that of the hinge 
86. As the rod 88 extends and retracts, tip 24 is accordingly straightened 
and rotated. 
Pistons 84 operate in accordance with commands from a command center (not 
shown) which indicates to hydraulic pumps 90 (FIG. 10) to increase or 
decrease the supply of an hydraulic fluid, such as oil, in hydraulic pipes 
92 thereby respectively extending or retracting rod 88. 
Reference is now made to FIGS. 12A-12D which illustrate four possible hull 
cross sections. In accordance with a preferred embodiment of the present 
invention, hull 10 has a cathedral planing hull cross-section, as shown in 
FIG. 12A. As can be seen, it is a multi-prismatic hull, comprising a 
central prism-shaped hull element 94 and two side hull elements 96 with 
keels 98 out of which extend the forward foils 12. The central hull 
element 94 has planing surfaces 97 and the side hull elements 96 have 
planing surfaces 95. Thus, the multi-prismatic hull has four planing 
surfaces making it a relatively efficient hull shape for planing. 
FIG. 12B illustrates an alternative embodiment of the present invention 
where the hull cross-section is in a catamaran configuration. In 
accordance with a second alternative embodiment of the present invention, 
and as shown in FIG. 12C, the hull cross-section is a deep V planing 
configuration with longitudinal strakes 99. In accordance with a third 
alternative embodiment of the present invention and as shown in FIG. 12D, 
the hull has a flat bottom which can operate as both a planing bottom and 
as a displacement hull. 
It is a feature of the invention that the shape of the hull 10 in 
conjunction with the forward foils 12 is relatively efficient For the 
hydrofoil, planing and undersea orientations. 
As is known in the art, a craft specifically designed for surface 
performance is shaped in a way which compromises its efficiency if 
submerged. For instance, planing hulls produce desirable surface 
performance. The deep V cross section fitted with longitudinal strakes, 
shown in FIG. 12C, is particularly efficient in rough water. However, a 
high lift planing bottom requires a wide beam which is inconsistent with a 
requirement of a narrow hull for undersea operation. 
The conventional undersea hull shape is a cigarette shaped hull. It 
provides efficient undersea operation but provides inefficient operation 
as a surface craft. As a surface craft, the cigarette shaped hull 
typically operates as a displacement hull not capable of high speeds or as 
a very narrow bottom planing hull which typically does not provide enough 
lift to produce high speeds. 
It will be appreciated that the craft of the present invention is 
configured to relatively efficiently operate as both as surface craft and 
as a submerged craft. The narrow cigarette shaped hull is fitted with 
completely retractable forward foils 12. When operating as a surface 
craft, the forward foils 12 carry the majority of the weight of the craft, 
assisted by a narrow planing bottom. This eliminates the drawback of the 
narrow hull operating as a displacement hull when operated as a surface 
craft. Moreover, in the undersea mode, the forward foils 12 are retracted 
leaving a craft with a narrow hull which is efficient for undersea 
operations. 
Reference is made back to FIGS. 12A-12D. In accordance with the preferred 
embodiment of the present invention, the voids in the hull are utilized 
for storage. The central prism-shaped hull element 94 provides a storage 
space for batteries utilized for providing power to the electric motor 44. 
The side hull elements 96 provide storage for fuel or the turbines 25. 
Additional fuel, typically for long voyages, can be stored in inflatable 
tanks 100, typically formed of rubber membranes, such as Neoprene (TM). 
The inflatable tanks 100 preferably remain flat against the sides of the 
hull 10 during short voyages when no fuel is stored there. 
The rubber membranes are typically bonded to the hull with a sticky 
substance such as glue. Additionally, the rubber membranes are fastened to 
the hull 10 with rigid metal strips. 
It will be appreciated that FIGS. 12A-12D illustrate the hull cross-section 
of the craft in the planing mode orientation of FIG. 3. As was shown in 
FIG. 3, in the planing mode, the forward foils 12 are partially retracted 
and the tips 24 are straight with respect to the struts 22. Thus, the 
forward foils 12 present a long chord to the movement of the water below 
them. This long chord is a relatively efficient planing surface and 
produces lift. 
Reference is now made to FIG. 13 which is a cross-section of the hull in 
the area near the end of the opening 67 for the craft in the undersea mode 
of FIG. 7. The forward foils 12 are completely retracted, as is mast 16. 
As can be seen in FIG. 13, the mast 16 and the detector dish 18 are 
retracted into a compartment 110. Compartment 110 is typically closed in 
the undersea mode, via sliding doors 112. Additionally, compartment 110 is 
typically filled with flotation devices 111 in the voids around the 
retracted mast 16. 
Reference is now made to FIGS. 14 and 15 which illustrate apparatus for 
streamlining the hull of the craft for the undersea mode of operation. A 
flexible membrane 120, such as of rubber, is preferably attached to most 
of the hull of the craft in the manner described hereinabove with 
reference to inflatable tanks 100. A multiplicity of water inlets 122 are 
located above the flexible membrane at a multiplicity of locations along 
the hull of the craft and associated with each water inlet 122 is a water 
pump 124. Upon commands from the command center (not shown), the water 
pumps 124 pump water from the inlets 122 into the flexible membrane 120, 
thus inflating the membrane 120 until it achieves the more streamlined 
position shown in FIG. 15. Once the membrane 120 achieves the desired 
state, the water pumps 124 cease pumping and act as valves to prevent 
water Flowing into or out of the inflated membrane 120. 
Upon suitable commands from the command center, typically in preparation 
for operation in a non-submerged mode, the water pumps 124 pump the water 
out of the flexible membrane 120 thus deflating the membrane 120 which 
subsequently adheres to the surface of hull. 
Reference is now made to FIGS. 16-19 which illustrate elements of the two 
propulsion systems. The first propulsion system typically comprises two 
turbines 25 (only one is shown in FIG. 16) which receive air from air 
intake inlets 26 during hydrofoil and planing operations and from air 
intake inlet 40 during partially submerged operations. Additionally, 
turbines 25 receive fuel from a fuel line 129 attached to fuel storing 
side hull elements 96 (not shown in FIGS. 16-19). 
The air from any of the air intake inlets 26 and 40 passes via air duct 130 
to filters 132, such as the Centrisep Air Cleaner/Mist Eliminator System 
by Aircraft Pourous Media, Inc of Glen Cove, N.Y. of USA located in front 
of each turbine 25. The filters 132 filter water spray and salt from the 
air and ensure that only clean air arrives at the turbines 25. 
Each turbine 25 combusts fuel with air. The power take off stage of each 
turbine 25 drives a gear 134 which transmits power through an axle 136. 
The rotation of axle 136 operates an hydraulic pump 138 which causes 
hydraulic fluid in hydraulic pipes 140 to flow and to cause motors 401 to 
turn. The motors turn propellers 52 which propel the craft forward. 
Exhaust gases from the turbines 25 is discharged through an exhaust 
manifold 142 to air outlet 42. 
It will be understood that propellers 52 rotate counter rotatively. As is 
known in the art, counter rotative rotation between two propellers 
achieves a relatively efficient propulsion. To produce movement in the 
reverse direction, each propeller 52 is rotated in the reverse direction. 
The second propulsion system comprises electric motor 44 and propeller 46. 
The electric motor 44 is Fun through power supplied by batteries stored in 
hull element 94 (FIG. 9). It will be appreciated that the second 
propulsion system is relatively quiet since no combustion is occurring. 
This quiet propulsion system is advantageous since it enables the crew of 
the craft to be more comfortable during the undersea operations. 
Additionally, the electric propulsion system has no exhaust gases and 
therefore, can be easily operated undersea. 
It will be appreciated that the elements of the two propulsion systems are 
located, as shown in FIG. 17, such that retraction can be easily 
performed. Thus, the hydraulic pipes 140 are typically flexible pipes, 
such as those made of rubber or plastic, which move easily during 
retraction and extension of rear foil 14. 
FIG. 18A pictorially illustrates an alternative embodiment of the first 
propulsion system. In this alternative embodiment, the rear foil 14 is 
mechanically retracted and extended. Turbines 25 rotate reduction gears 
150 which, in turn, turn geared power rods 152. As geared power rods 152 
turn, they turn gears (not shown) which turn the propellers 52. 
Each propeller 52 is turned by a 90.degree. gear system (not shown) built 
into casing 404 and powered by geared power rods 152. Power rods 152 have 
outer teeth 156 which are driven by a cross shaped recess 157 of a spur 
gear 158. Spur gear 158 additionally has outer teeth 159 which are turned 
by reduction gear 150, which, as mentioned hereinabove, is powered by one 
turbine 25. 
A rear foil retraction and extension system is comprised of a motor 402 for 
turning a pinion 403. Pinion 403 moves a toothed rack 405 which is part of 
rear foil strut 54. As pinion 403 moves toothed rack 405, rear foil strut 
54 retracts and extends. During retraction or extension, geared power rods 
152 slide inside the cross-shaped recess 157 of spur gear 158, 
continuously providing power to the propellers 52 regardless the elevation 
of the rear foil 14. 
FIG. 18A additionally illustrates the location of the electric motor 44 
with respect to the alternative first propulsion system. Also seen in FIG. 
18A are batteries 165, such as silver cell or lead batteries, stored in 
hull element 94, used for powering electric motor 44. 
FIG. 19 shows a top view of the first propulsion system. The two turbines 
25 lie generally aside one another. As can seen, air duct 130 is a 
branched passage, with one air duct branch 131 bringing air to one turbine 
25 and a second air duct branch 133 bringing air to a second turbine 25. 
Air intake inlets 26 comprise doors 168 which are opened and closed upon 
command from the command center via a piston typically comprising two rods 
172. Seals 174 maintain the closure of the doors 168 during undersea 
operations. 
Reference is now made to FIGS. 20-21 which illustrate elements of a 
retraction system for the mast 16. For clarity, the mast 16 is shown 
retracted. The retraction system comprises an electric motor 180 coupled 
to a gear 182 for rotating at least one disk flange 184. Disk flanges 184 
are connected to a drum 179 which forms the base of mast 16. Each disk 
flange 184 is geared along the outer side for coupling with gear 182 and 
the inner side is machined as a bearing seat for holding one of a set of 
extra strong spherical roller thrust bearings 186, such as the Series 292 
type from SKF. Bearings 186 also sit on a sea 188 which is connected to 
the hull 10. Since the mast 16 is attached to flanges 184, when the 
flanges 184 rotate, the mast 16 extends or retracts. 
In accordance with an alternative embodiment, two gears are utilized 
instead of gear 182. In the alternative embodiment, each gear rotates one 
of flanges 184 and the gears rotate in unison. 
FIG. 20 additionally illustrates the air intake system of the mast 16. Air 
intake inlet 40 is connected to a pipe inside mast 16 which opens into a 
fixed torus manifold 192 with an inner hole 193. Torus manifold 192 is 
connected to air duct branches 131 and 133. The circular shape of the 
manifold 192 can be seen in FIG. 16. Pipe 190, as part of the mast 16, is 
connected to drum 179 and thus, rotates around the torus manifold 192 
during extension or retraction of mast 16. 
FIG. 21 illustrates the air exhaust system of the mast 16. Air outlet 42 is 
connected to a T-shaped pipe 194 which, in turn, is connected via o-rings 
196 to exhaust manifold 142, located in the inner hole 193 of torus 
manifold 192. Pipe 194 rotates with respect to exhaust manifold 142 during 
extension and retraction of the mast 16. Sealing between the pipe 194 and 
the exhaust manifold 142 is provided by o-rings 196. 
Reference is now made to FIGS. 22, 23A and 23B which illustrate elements of 
the undersea propulsion system. The undersea propulsion system comprises a 
nozzle 210, similar to a Kourt nozzle, for ensuring that the majority of 
the water passes through a propeller disk created by the movement of 
propeller 46. As is known in the art, this makes for quieter propulsion. 
The undersea propulsion system additionally comprises a water inlet system, 
shown in detail in FIG. 23A, comprising two inlet openings 212, one on 
each side of the craft, covered with grills 213. The water inlet system 
additionally comprises two tunnels 215, one on each side of the craft, for 
funneling the incoming water towards the propeller 46. The rotation 
propeller 46 thrusts the water out of nozzle 210 via opening 214, and in 
this manner gives forward thrust to the craft. 
Reverse thrust is achieved by reverse rotation of the propeller 46. For 
reverse thrust, water is sucked into the water inlet system through 
opening 214 and sent out through the inlet openings 212. 
Steering is achieved through movements of rudder 50 about a rudder pivot 
217. The angle of the rudder 50 with respect to the hull 10 defines the 
direction in which the water flows out of opening 214 and thus, defines 
the direction in which the craft moves. The angles of control surfaces 48 
with respect to the horizontal axis of the hull 10 also define the flow 
direction of the water. Additional movement control is provided outside of 
the propeller area by control surfaces 48 which, as mentioned hereinabove, 
control pitch and roll movement of the craft. 
The flow of water is shown in FIG. 23A which shows a top section of the 
water inlet system. The water inlet system is shaped to provide a large 
flux of water across the propeller 46. To increase the flux of water, a 
inlet extender 216 is typically included in the water inlet system. Inlet 
extender 216 is a pivoted scoop which extends beyond the side of the hull 
10 to bring water into the water inlet system. Inlet extender 216 is 
typically included in craft whose hull 10 is so streamlined that water 
flows over inlet openings 212 rather than entering the inlet. Inlet 
extender 216 produces a slightly less streamlined hull shape but increases 
the flux of water across the propeller 46. 
FIG. 23B is a cross-sectional view through the nozzle 210. It can be seen 
that the nozzle 210 is only slightly larger than the radius of the 
propeller 46. This ensures that as mentioned hereinabove, the majority of 
the water passing in the vicinity of the propeller 46 actually pass 
through the propeller disk created by the movement of the propeller 46. 
In accordance with an alternative embodiment of the undersea propulsion 
system of the present invention and as illustrated in FIGS. 24, 25A and 
25B, the propeller 46 is replaced by a centrifugal pump 220, such as is 
typically used in air conditioning systems. An example centrifugal pump 
220 is the Radial Compressor by Rosenberg Ventilatoren GmbH of 
Kunzelsau-Gaisbach, West Germany. The water inlet system remains the same 
as in the previous embodiment; however, it brings the water to an inlet 
axle 222 (FIG. 25B). The centrifugal pump 220 then spins the water in a 
direction perpendicular to that of the inlet axis. The water is collected 
in a pipe 224 whose radius of contour increases from a small value 
beginning at a location 220 until it reaches the size of opening 214. The 
water is directed along the pipe 224 to the opening 214. 
The centrifugal pump 220 is operated by motor 44 coupled to a gear box 226 
(FIG. 25A) operating gears 228. Gears 228 engage teeth on a disk 229 
connected to centrifugal pump 220. 
Reference is now made to FIGS. 26A, 26B, 27, 28, 29 and 30 which illustrate 
a further alternative embodiment of the undersea propulsion system of the 
present invention. In this embodiment, the propulsion system is a fishtail 
230 which produces forward thrust by undulating back and forth. The 
fishtail 230 can be located inside the tunnel 215, as in FIG. 26A, or the 
water inlet system can be eliminated, as shown in FIG. 26B. 
The fishtail 230 is typically comprised of a multiplicity of chain links 
232 linked together as in a bicycle chain. The chain links 232 are 
numbered 2-9 in FIG. 28 and the first link is the attachment point to the 
hull 10. Each chain link 232 is controlled via a push-pull element 234 
(FIG. 28L, such as the Push Pull by Teleflex Co., which is individually 
controlled via a power device 236 (FIG. 29), such as an hydraulic pump and 
piston. 
Each push-pull device 234 is located eccentric from an axis 238 of its 
corresponding chain element 232. Each push-pull element 234 snakes through 
holes in the axes of the entirety chain links 232 preceding its 
corresponding chain link 232. 
The push-pull elements 234 are controlled via the command center such that 
they operate in unison to produce an undulation. As is known in the art, 
the undulation and the forward motion of the craft produce eddies 240 
(FIG. 27) staggered along the sides of the fishtail 230. 
As shown in FIG. 27, each eddy 240 begins as eddy 240a near chain links 1 
and 2. This happens because fishtail 230 drags with it as a wake the water 
near chain links 1 and 2, giving it rotational motion. 
The undulation of the fishtail 230 causes the fishtail 230 to move away, in 
both the forward and transverse directions, from the newly begun eddy 240a 
which remains stationary in the water. The fishtail 230 returns to eddy 
240a at a location further along the fishtail 230, in a region of 
concavity such as at links 4-6. The fishtail 230 grabs the eddy and pulls 
it along, as described hereinabove, giving it more rotational energy. This 
amplifies the eddy to the size shown in eddy 240b. The process continues 
such that the eddies 240 along the body of the fishtail 230 are 
progressively larger. 
The final eddy, 240c, is typically quite large. The tail 241 of the 
fishtail 230, chain links 7-9, typically grabs the eddy 240c when the tail 
241 is oriented nearly perpendicular to the forward direction. The water 
on the eddy side of the tail 241, the pressure side, typically moves 
fairly slowly while the water on the non-eddy side, the suction or leeward 
side, of the tail 241 moves more quickly. Thus, a lift vector in a 
direction close to that of the forward motion is created, transferring 
energy from the eddy 240c to the fishtail 230 thereby giving forward 
thrust to the craft. 
In the manner described hereinabove, the eddy 240c gives power to the 
fishtail 230. To increase the power of the eddies 240, in the embodiment 
of FIG. 26A, a multiplicity of water jets 242 are preferably installed 
along the inside of the tunnel 215. The water jets 242 located near the 
locations of concavity of the fishtail 230 are turned on in order to 
amplify the energy of the eddies 240 near the water jets 242. The energy 
from the water jets 242 is converted, via the eddies 240 and through lift 
on the tail 241, to forward thrust of the craft, thereby amplifying the 
effect of the eddies 240. 
It will be appreciated that the water jets 242 are typically included in 
the embodiment of FIG. 26A because the eddies 240 often cannot be 
completely formed due to the restricted space in the tunnel 215. Thus, 
water jets additionally replace any lost energy due to the restricted 
space. 
In accordance with an alternative embodiment of the fishtail undersea 
propulsion system, shown in FIG. 30, the fishtail 230 is suspended from 
the hull 10 via suspending arms 244, thereby enabling a head 246 of 
fishtail 230 to move freely. This enables the first eddy 240a to be 
created more efficiently. 
Suspending arms 244 are connected to fishtail 230 via hollow hinges 248. 
Inside of suspending arms 244 and hollow hinges 248 are located all the 
power lines and communication equipment necessary for operating Fishtail 
230, such as portions of the push-pull elements 234 and hydraulic pipes. 
It will be appreciated that the fishtail undersea propulsion system 
described hereinabove is a relatively quiet system. The only noise is 
created by the power devices 236, each of which is fairly small and can be 
individually enclosed to reduce noise. 
It will be appreciated by those skilled in the art that the present 
invention is not limited by what has been particularly shown and described 
hereinabove. The scope of the present invention is defined only by the 
claims which follow: