JPH02102889A - Water sliding type catamaran - Google Patents

Abstract

PURPOSE: To improve efficiency by supporting an upper structural body through at least one strut onto a pair of long thin pontoons separated from each other at a distance and parallel to each other, reducing drag in the low speed before planing, and changing the sectional width in the planing speed. CONSTITUTION: A catamaran ship 10 is provided with a pair of long thin pontoons 12 separated from each other a distance and parallel to each other, and an upper structural body or a platform 16 are supported on them through at least one strut 14. The strut 14 is thinner than the pontoon 12 and has a streamlined nose part section 20, and the maximum thickness is set in at least two times that of the strut 14. The pontoon 12 is formed into such a shape as to plane on the water surface at high speed, pointed chines 22 are provided on inward and outward ends 24, 26, and a widest part of the pontoon 12 is under an attaching point to the strut 14 and also under the upper surface 28 of the pontoon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates generally to catamarans in which a superstructure or platform is supported on a pair of hulls (hulls). In particular, it relates to ships gliding on water at high speed.

[Prior art and its problems] Ships that can glide on water can reach very high speeds because they are lifted above the water, reducing surface resistance and wave drag. be. Many boats have retractable leg-shaped hydrofoils at the front end of the boat that are raised out of the water at high speeds. Other designs use ski-like structures. However, both of these ships have hull parts that are submerged at pre-planing speeds and therefore experience fairly high resistance at such speeds.

When a ship begins to be lifted above the water, a so-called drag hump or wave-making resistance mountain occurs, causing the bow to rise and the stern to fall, requiring a large force to obtain planing speed.

In catamarans with twin hulls supporting the platform or superstructure, a submerged buoyancy hull is used to support the superstructure on struts above the water surface.

known to hold. Such a structure is described in US Pat. No. 3,886,557. This structure uses a rectangular hull to support the boat platform. This increases stability.

The design of this structure is such that the water surface line when stopped is approximately the midpoint of the striated line due to the boat's load. Although not specifically designed for this purpose, the lower hull of the ship referenced here allows it to have sufficient power and high speed to plan. However, this structure is not very efficient from a glide point of view, as it must be raised a certain basic distance above the water surface in order to glide.

[Means for Solving the Problems and Their Effects] An object of the present invention is to provide a catamaran that can glide on the water surface at high speed.

According to the present invention, the provided catamaran has a pair of parallel and elongated pontoons spaced apart.
and at least one strut extending upwardly from each of said pontoons, said strut having a streamlined nose area and having a width narrower than that of said pontoon to which it is attached; a superstructure supported on struts and supported above the water line, each said pontoon having a sliding surface for sliding on the water surface at high speeds, and an inner and outer surface thereof; the pontoon has a sharply pointed chine (ehine) at its side end, the cross-sectional width of the pontoon varying at least along its height, while the widest point of the cross-sectional width is below the top of the pontoon; It includes things that are made to be.

The struts have streamlined front areas and are narrower than the attached pontoons, which provide most of the buoyancy to lift the platform or superstructure out of the water. The buoyancy design of the pontoon should preferably be such that the water line lies at or close to the top of the pontoon and the majority of the struts are out of the water when at rest under full load conditions. Make sure you are there. However, the water surface line may be slightly above or below this point, and if a high load is applied, a portion of the strut may be submerged in the water.

Since this pontoon is always close to the water surface, there is less vertical distance to lift the vessel above the water surface for planing, and therefore the planing resistance is low. The width of this pontoon is at least twice that of the strut, preferably about three times as wide. By making the surface of the strut thin and pointed, the drag of the water at the speed before planing is reduced, and as the speed of the ship increases, the planing surface on the lower side and the chine at the end of the strut will pontoon above the water surface. Lift it up and slide it on the water surface. The long, relatively narrow pontoons, thin struts, and height of the superstructure on the pontoons reduce vertical acceleration in waves when planing and increase boat stability.

Preferably, this sliding surface has an overall V-shape and is asymmetrical. Preferably, this surface has an inward and an outward deadrise angle, the inward fill angle being preferably greater than the outward fill angle. The inward slope angle is preferably within the range of 10 to 90'', while the outward slope angle is within the range of 10 to 25''.

The top surface of each pontoon may be V-shaped or circular and may be either symmetrical or asymmetrical with respect to the line attached to each strut. Preferably, each pontoon has a downwardly curved lip at its outer end and a similar lip at its inner end to facilitate flotation and reduce drag.

The shape of the pontoon is designed to reduce wetted surface area, which reduces drag at low speeds before skiing, and improves efficiency at skiing speeds by changing its cross-sectional width. ing.

[Embodiment] Figures 1 to 3 and 8 show a catamaran lO according to a first embodiment of the invention. Catamaran lO shown in the figure
is a small power-driven pleasure boat. However, the present invention is applicable to vessels of any size, 100 feet or more in length, running at fairly high speeds, such as pleasure craft, merchant vessels, warships, etc., and even sailing vessels. It can be applied.

The catamaran lO is essentially a pair of spaced parallel elongated pontoons or hulls 12 with at least one strut 14 extending upwardly therefrom and a superstructure supported above the struts. body or platform 16. In the embodiment of FIGS. 1-3, only one strut is shown extending along the length of each pontoon, but as shown in FIG. There is no problem even if strut 50 is used.

As shown in FIG. 3, the pontoon 12 is submerged below the water surface 18 when the vessel is at rest, while the superstructure 16 is raised out of the water. A pontoon is a buoyant member.
Made of lightweight material, for example metal, wood, plastic or fiberglass, or a combination of these materials, they are hollow or filled with a suitable buoyant material such as foam.

As shown in Figures 2 and 3, the struts 14 are thinner than the pontoons and have streamlined nose areas 20 to reduce drag when navigating through water at low speeds.

The maximum thickness of the pontoons is at least twice that of the struts, preferably about three times. Preferably, the length of the pontoon is at least the same as the length of the superstructure. The buoyancy design of the pontoon shall be such that, when at rest under normal or fully loaded hull conditions, the waterline 18 is at or near the top of the pontoon, as shown in Figure 3. . That is, most or all of the buoyancy that lifts the ship out of the water is provided by the pontoon. Depending on the buoyancy of the pontoon and the boat load, the water line 18 may be slightly above or below the position shown in FIG. At very light loads, half of the pontoon's volume will be out of the water, and at full or high loads, part of the struts will be submerged. The buoyant force of the submerged parts of the pontoons and struts is equal to the total weight of the ship in air.

Pontoons themselves are shaped so that they can glide over water at high speeds. As shown in FIG. 8, each pontoon has a sharply pointed chine 22 at its inwardly and outwardly directed ends 24.2B, respectively, while the widest part of the bontoon is attached to the strut below the point and at the pontoon. It extends below the top surface 28 of the. The lower surface 30 of the pontoon has a sliding surface, preferably as shown in FIG.
It is V-shaped and asymmetrical. In the embodiment of FIG. 8,
The top of the pontoon has an inverted V shape. This upper surface may be symmetrical or asymmetrical as shown.

As seen in FIG. 8, the pontoon running surfaces 30 have inward and outward deadrise angles 32,34, respectively, which are preferably different, with the inward angle being greater than the outward angle. This asymmetry and different deadrise angles enhance the boat's turning and skewing performance.

In the embodiment shown in FIG. 8, the outward deadrise angle is about 15'' and the inward angle is about 28 degrees.

However, this outward slope angle may be any angle between 10 and 25 degrees, and the inward slope angle may be any angle between 10 and 25 degrees.
and 90''. Examples of various types of pontoons are shown in FIGS. 9 to 15, and will be described in detail later.

Returning to Figures 1 to 3, it can be seen that the area in front of each pontoon is similarly streamlined and curved towards a point or approximately horizontal line at the bow 3B. As shown, this point may be at any suitable location between the center and top surfaces of the pontoon, and may also be shaped like a water ski and above the top surface of the pontoon. This improves the sliding properties of the pontoon, and the gentle streamlined shape reduces drag at pre-sliding speeds. The rear portion of the pontoon is also tapered and is preferably cut off before it converges to a point, as shown in FIGS. 1 and 2.

An optional counterbalance plate 38 or inward counterbalance foil (f'all) 40 is shown in FIG.
, the stern, is located nearby and helps maintain balance and stabilize the pitch of the boat. This balancing plate is necessary for relatively large boats, and in this case, it is necessary to control the generation of so-called wave resistance crests when the boat starts to slide by adjusting the balancing angle. Or again,
This can also be used to control the glide angle regardless of the size of the boat. A counterbalance plate is attached to the rear end of the V-shaped slide. Balancing foils are used in a similar manner, but their contribution to pitch stability is greater when operating at speeds before wave resistance peaks form.

Preferably, the struts 14 are tapered at their front and rear ends, as shown in FIG. 2, to reduce drag at low speed levels. If manufacturing permits, the taper on one side of the strut at the aft end or stern may be different from the taper on the other side. The rear portion of each strut may be cut off before it converges to a point, as shown in FIG. In the embodiment shown in FIG. 2, the struts are generally vertical;
Mounted along the centerline of the top surface of the pontoon. However, they may also be mounted off the centerline of the pontoon, and this will be discussed later in Section 4.10.15.
This will be explained in detail using figures.

Depending on the purpose of use, an appropriate upper structure ta is mounted as appropriate. In the embodiment shown in FIGS. 1 to 3, the boat is a small-sized, motor-driven pleasure boat. As shown in FIG. 3, this superstructure is supported above the water surface for one pontoon position when the ship is at rest. As shown in Figure 1, the upper and lower surfaces of the superstructure near the ship η are preferably tapered to a horizontal line passing through the bow °52, the distance of which this horizontal line extends from the bottom to the upper surface of the superstructure. It should range between 10 and 100%, preferably between 40 and 100%. In this embodiment, this bow line 52 is located upward from the bottom of the superstructure at a distance of approximately 65% of the total height. As shown in FIG. 1, the upper surface of this transverse beam structure is tapered downward near the stern.

The superstructure shown in FIG. 3 has a central lower portion 54 which converges at a point at the bow, extends along the entire length of the superstructure, and terminates at the stern. This v-shaped feature is preferably centered at or near the centerline of the superstructure.

Preferably, the forward end of this formation 54 converges below the superstructure at or near the bow, while the aft end terminates near the stern of the superstructure, and preferably has a taper therein. It stands out perfectly. Preferably, the side ends of the V-shaped components extend one thickness of the inside of each strut.
It ends at double. At the bow, this V-shaped component reduces wave impact loads on the transverse beam structure in rough seas, and at the stern, it increases the area underneath the outboard motor. Makes installation easier.

There is another embodiment that is equipped with one or more of these longitudinally extending ■-shaped components 54. One such variant is shown in FIG. 4, in which the V-shaped feature 55 of the structure is attached to the upper end of the strut on the underside of the superstructure. An inboard motor can be provided in each of these square parts. In addition to reducing wave shock loads on the structure, this embodiment allows mounting points for two outboard motors at the stern, allowing for a large area of the transverse structure. Stress can be reduced by distributing the strut load. A large V-section in the bow can be provided to provide a large mounting area, which is useful when larger boats are equipped with relatively large engines. One or more V-shaped features can be added between the struts.

Inboard or outboard engines or sails can be used for power. In the embodiment shown in Figures 1-3, an outboard motor 56 drives a propeller, which is shown attached to the transom of the superstructure. One or more motors can be mounted on the transom. In the case of inboard motors, this should be located either on the superstructure, on the elongated V-shaped area below the superstructure, on the pontoons, or on locally enlarged strut-pontoon junction areas. I can do it. This latter embodiment is illustrated in FIG. 14 by a bulge 57 shown in dashed lines. Power can be transferred from the inboard motor to the thrusters using a suitable drive transmission system.

The superstructure shown in FIG. 1 has a suitable seat 58, a front windshield 60, and a cargo compartment (not shown). Of course, it is possible to change the design of this boat platform depending on the size of the boat and its intended use.

Preferably, the transom of the superstructure overlies at or in front of the area of the transom of the strut, while the transom of the strut preferably overlies at or in front of the area of the transom of the pontoon.

When the ship shown in Figures 1 to 3 is stationary or traveling at low speed, the pontoon is submerged below the waterline 18 near its top. This will of course vary depending on the load on the boat. That is, in practice, this water surface line [8] may be above or below the position shown in FIG. 3, and if the load is very light, it may be below the top surface of the pontoon. The reason why there is little wave action is because most of the ship's body is out of the water and away from the impact, and because the maximum width of the pontoon is below the water surface, it is relatively close to the water surface. This is because the pontoon is designed to have a small area and a small braking action. When sailing at slow preplaning speeds, the narrow, streamlined struts and fully or nearly submerged pontoons reduce the drag experienced by the ship.

As the speed increases, the planing surface and the chines of the struts lift the ship above the water surface until the planing begins. Since the pontoons are not submerged too deeply below the surface of the water prior to planing, the amount of lift required to raise the vessel completely above the surface of the water is small or minimal. The water slide line 61 at that time is shown in FIG. The mountain of wave-making resistance when the ship starts running due to planing is lowered by the width of the pontoon, that is, the narrow width of the ship, and the shape of the pontoon. - Once the ship starts sliding on the water surface, the wave resistance decreases and it reaches high speed. Planing catamarans are very stable due to the low vertical acceleration when planing, which is due to the elongated pontoons with planing surfaces, thin struts, and superstructures on the pontoons. It depends on the height.

Several embodiments of pontoon shapes are shown in Figures 9 to 15, all of which are shown in Figures 9 to 15.
Alternatively, it has a sliding surface that is attached to a strut 14 of a ship as shown in Figure 4. The pontoon 62 shown in FIG. 9 has the same sliding surface as shown in FIG. 8, but its upper surface 6G is not angular but circular or oval. A strut L4 is attached to the centerline of the top surface B6. The struts 14 in FIG. 9 are shown inclined inwardly.

Although the struts are generally vertical in embodiments of the invention, they can optionally be inward planes, outward planes, or curved. This plane is determined by the desired width of the passenger platform or superstructure relative to the pontoon spacing. Third
In the figure, the width of the superstructure is the same as the spacing of the outer surfaces of the struts, while in FIG. 4 the width of the superstructure is wider than the spacing of the struts.

10 and 11, the pontoon 70 is shown to be asymmetrical, having a flat inward facing surface 72 and an outwardly angled sliding surface 74, with outward facing chines 76 forming the sliding surface. 74 is separated from the upper surface 78.

The mounting of the struts 14 in this embodiment is asymmetrical. This type of pontoon is also shown on the ship in Figure 4. Cantilever type underwater as an option [0 is shaft 8]
It is rotatably attached to each pontoon 70 via 2, which is inclined downwardly and inward of the pontoon. The hydrofoil can be retracted, as shown in FIG. 11, in which case it is pivoted backwards to a position where it is flush with a portion of the lower surface of the pontoon. Hydrofoils of this type can be used as an option on any of the pontoon structures shown to provide additional lift. This wing is similar to that of a normal hydrofoil (it does not have the power to lift the boat above the water surface, but only serves to improve efficiency in many cases. Figures 3 and 4 show the pontoon of this auxiliary hydrofoil 80). For example, in heavy and large boats, it is preferable to install hydrofoils to increase lift.

If hydrofoils are used, they are preferably mounted on both sides of the boat near the center of gravity. One or more hydrofoils can be attached to each pontoon. If one or more hydrofoils are mounted on both sides, the center of their effective area should be near the center of gravity. The underwater g80 shown in Figure 4 is generally horizontal and extends between the pontoons. Specialized hydrofoils are used in specific cases, usually on relatively large boats that require significant lift.

Another pontoon configuration 90 is shown in FIG.
This has a round oval upper surface 91, inward and outward facing chines 92,94, and a symmetrical V-shaped sliding surface 9.
I have B and . 8 parts with dents on the inside 98.10
0 extending along the inward and outward facing ends of each pontoon. Some of these lip the lift, thus reducing the splash and reducing drag when rising from the water. This portion can be provided at the inward and outward ends of any of the shapes of pontoons shown in FIGS. 8-15. In some cases, this may be applied only to the outwardly facing end, but preferably it works better if it is also applied to the inwardly facing end, as shown in FIG.

The terminal part of this 8 part is 90'' from O to the horizontal downwards.
is tilted at an angle of In other words, this direction can be any angle between horizontal and vertical. In the case of Figure 12, this downward angle is close to vertical, but for smaller boats it is preferred that this angle be between 10 and 15" from the horizontal. In one embodiment of a small trailer-type pleasure boat according to the present invention, a portion of the width of approximately 3% of the maximum width of the pontoon was used, although any portion of the same size could be used. .

A pontoon shape 110 is illustrated in FIG.
and an inwardly and outwardly sloping portion 120. separated from the central portion by edges 124.126.
It consists of 122. 8 parts or ridge-like parts 12
8 and 130 are provided at the edges 124 and 126, respectively, as shown.

Still another pontoon 140 is shown in FIG.
and have. The pontoon 150 shown in FIG. 15 has substantially the same shape as that shown in FIG. 10, but the top surface 152 is rounded rather than angular. An outer end 8 154 is shown at the outward facing chine 15B, and an auxiliary 8 158 is provided at the submerged surface IBO as shown.

The actual choice of pontoon shape is determined by the overall boat design specifications and costs vary depending on the shape and the construction materials used. Although all of the shapes shown can be used to advantage, the preferred small boat shape has a V-shaped submerged surface and a rounded top, and has a low speed before planing. Minimizes wet surface area.

An asymmetric type is suitable for improving turning performance. However, this is not necessarily a necessary condition, and symmetrical shapes can also be used to great advantage according to the invention.

An alternative embodiment of the lower surface of the pontoon is shown in FIGS. 6 and 7 to reduce drag.

In this figure, a staircase 170 is provided in the submerged surface and an opening 172 is provided through which air can be directed to the area behind said staircase via a suitably provided internal passageway 174.

One of the small trailer-type pleasure boats shown in Figures 1 to 3.
In one embodiment, the strato soto 14 is vertical, has a streamlined nose, and has a tip near the stern;
The cut portion is reached at about 70% of its maximum width.

The width of the pontoon is about three times the width of Stora Soto, and the ship is tagged to a point located at about 65% of the height above the keel, with outward and inward direction. The deadrise angles are 15 and 27.5@, respectively. The pontoon has inner and outer side ends, and its upper surface is in the shape of an inverted V with an angle of approximately 456 degrees to the horizontal. A transverse beam structure is provided above the water surface at rest, approximately one time the height of the pontoon, with a width equal to the distance between the outer surfaces of the struts, and a center converging towards a point on the bow. It has one V-shaped feature below the taper line, which is cut at the stern and whose sides end inside each strut at approximately one strut thickness. The upper and lower surfaces of this transverse H5i structure taper to the horizon near the bow, with the bow extending approximately 6-5% of the structure's height upwards from the bottom of the structure. It is located in a place.

The transom of this structure is located forward of the strut and pontoon stern, approximately 15% of the length of the boat. This crossbeam structure is approximately 1
It has a retractable windbreak with a 5° angle. However, the above dimensions are listed for one possible design as an example, and it is possible to design various ships by changing these dimensions.

Although various embodiments according to the present invention have been described above, it is easy for a person skilled in the art to make various changes without departing from the spirit of the present invention and the scope of the claims. It is included in

[Brief explanation of drawings]

FIG. 1 is a side view showing a typical example of a small boat equipped with a sliding twin-hull structure according to the present invention, and FIG. 2 is a partially cutaway view taken along line 1-1 in FIG. 3 is a front view of the boat shown in FIG. 1, FIG. 4 is a front view showing the arrangement of the pontoon and struts according to another embodiment, and FIG. 5 is a cross-sectional view showing the configuration of the multiple struts. 2 is a cross-sectional view similar to that shown in FIG. 2, FIG. 6 is a side view of the stepped pontoon, and FIG.
8 is an enlarged cross-sectional view taken along line 8--8 of FIG. 1; FIG. 9 is a plan view of the figure taken from below; FIG. 10 is an enlarged sectional view similarly showing a pontoon of another shape and an expandable hydrofoil. FIG. 11 is a plan view of FIG. 10 viewed from below. , 12 to 15 are enlarged sectional views showing the shape of a pontoon according to still another embodiment.

Claims (1)

Claims: (1) a pair of spaced apart and parallel elongated pontoons; at least one strut extending upwardly from each pontoon; and a nose region in which the struts are streamlined. and having a width narrower than that of said pontoon to which it is attached; a superstructure supported on said struts and supported above the water line; The pontoon has a sliding surface for sliding on the water surface at high speed, and sharp chines at its inner and outer side edges, and the cross-sectional width of the pontoon changes at least along its height direction. a catamaran, wherein the widest point of its cross-sectional width is below the top of said pontoon, said pontoon lying at least substantially below the surface of the water when the vessel is stationary in the water; . (2) said pontoon has sufficient displacement buoyancy to raise said superstructure and at least a majority of said struts are out of the water when the vessel is at least stationary in the water; 2. A catamaran as claimed in claim 1, wherein said pontoon has a water line lying near the top of said pontoon. 3. The catamaran of claim 1, wherein the lower surface of the pontoon is generally V-shaped. (4) The catamaran of claim 3, wherein said V-shaped surface is asymmetrical. 5. The catamaran of claim 1, wherein the upper surface of each pontoon is circular in cross section. 6. The catamaran of claim 5, wherein said rounded surface is oval shaped and asymmetrical with respect to the line of attachment of said strut. 7. The catamaran of claim 1, wherein said upper surface of each said pontoon has an inverted V-shape. 8. The catamaran of claim 1, wherein the planing surface of each pontoon has a heel angle on each side of its keel. (9) The catamaran according to claim 8, wherein the hull heel angle on the inward side is larger than that on the outward side. (10) The inclination angle of the hull on the inward side is 10 to 9.
9. A catamaran according to claim 8, wherein the catamaran is between 0[deg.]. (11) The hull slope angle on the outward side is 10 to 2.
9. A catamaran according to claim 8, wherein the catamaran is between 5[deg.]. (12) each of the pontoons has a downwardly curved, internally concave lip extending along an outer end thereof;
A catamaran according to claim 1. 13. The catamaran of claim 12, wherein each pontoon has another downwardly curved, internally recessed lip extending along an inner end thereof. (14) The catamaran according to claim 12, wherein the angle of the lip is between 0 and 90 degrees with respect to the horizontal. 15. The catamaran of claim 12, wherein said lip terminates at a downward angle of between 10 and 15 degrees relative to the horizontal. 16. The catamaran of claim 1, wherein the forward area of each pontoon curves toward a point on the bow. 17. The catamaran of claim 16, wherein the tip of each pontoon is located above the center plane of the pontoon. 18. The catamaran of claim 1, wherein the tip section of each pontoon is curved toward a line of the bow. 19. The catamaran of claim 1, wherein the thickness of the rear portion of each pontoon tapers toward the rear end of the pontoon. 20. The catamaran of claim 1, wherein said strut is mounted off-center to said pontoon. 21. The catamaran of claim 1, wherein the struts are vertical. (22) The catamaran of claim 1, wherein the strut is inclined. 23. The catamaran of claim 1, wherein the superstructure has at least one V-shaped structure extending along its lower surface, and has a pointed end near the bow of the superstructure. 24. The catamaran of claim 23, wherein the aft end of the V-shaped structure terminates near the stern of the superstructure. (25) The catamaran of claim 23, wherein the V-shaped structure is located near the centerline of the cross section. (26) a pair of V-shaped structures extend at each end of the upper structure along a lower surface of the upper structure; and a pair of V-shaped structures extend along a lower surface of the upper structure; 24. A catamaran according to claim 23, wherein the catamaran is mounted on a surface. 27. The catamaran of claim 26, wherein one inboard engine is located in each of the V-shaped structures. 28. The catamaran of claim 1, wherein at least one cantilevered hydrofoil is attached to each of said pontoons. (29) a spread position in which the wings are spread in a direction between the two pontoons in a direction toward and away from the inside of the pontoons; and a stowed position in which the wings are flush with one surface of the pontoons. 29. A catamaran as claimed in claim 28, including storage means for moving each of said hydrofoils between said hydrofoils. 30. The catamaran of claim 1, wherein an inwardly directed counterbalance foil is attached to the aft end of each of said pontoons, said counterbalance foil extending inwardly and away from the axis of said pontoon. (31) The catamaran according to claim 1, wherein a rearwardly projecting counterbalance plate is attached to the rear end of the sliding surface of each of the pontoons. (32) The lower surface of the pontoon is V-shaped and 2
32. A catamaran as claimed in claim 31, having two flat running surfaces and also having a rearwardly projecting counterbalance plate attached to the aft end of each flat running surface of the pontoon. (33) The sliding surface of each of the pontoons has a plurality of steps spaced apart in its longitudinal direction;
A catamaran according to claim 1. 34. The catamaran of claim 33, including supply means for supplying gas to the area behind each of said stairs. (35) The thickness of each said pontoon is at least twice that of said attached strut.
Catamaran listed. 36. The catamaran of claim 1, wherein two struts extend upwardly from each of said pontoons and have upper ends attached to said superstructure. 37. The catamaran of claim 1, wherein the area where the strut connects with the pontoon is enlarged, and each onboard engine is located within the enlarged area.