Abstract:
A boat hull having sealed rigid chambers and a perimeter inflatable portion positioned and attached laterally outward thereof. The perimeter inflatable portions provide redundant buoyancy and allow loads acting upon the hull to be shifted laterally without compromising stability of the boat.

Description:
RELATED APPLICATIONS 
   This application claims priority benefit of U.S. Ser. No. 60/579,050, filed Jun. 10, 2004. 

   BACKGROUND OF THE INVENTION 
   Rigid hull inflatable boats are well known in prior art and have been used as transportation on the water whereby the inflatable members provide a buoyant force to keep the boat floating on water. 
   Chambered hull boats have been disclosed in the prior art and one such boat owned by Aluminum Chambered Boats, LLC of this application is U.S. Pat. No. 6,520,107 which disclose a multiple chambered boat where the chambers are positioned on the lateral end forward portions of the hull. 
   By way of background, stability tests are required for certain applications Coast Guard approval, and particularly for a commercial passenger service. Such stability tests position the maximum number of people the boat can hold is placed on one lateral side portion of the boat. With a normal type of boat, this will tip or seriously compromise the balance of the buyoancing forces adapted to handle the load. 
   It should be further noted that many military and law enforcement boats engage in a “fendering” operation with when these boats are approaching vessels at high speeds and do not allow for a great deal of time to de-accelerate the boat. The fendering maneuver is particularly useful in high-speed pursuit where the boat with the perimeter inflatable collar must engage a boat at sea, presumably under high speeds, de-accelerating such that the perimeter buoyant portion further allows for a certain amount of de-acceleration upon impact to prevent or mitigate damage to either vessel. 
   Many inflatable chambers as disclosed in the prior art comprise either rigid chambers or inflatable chambers in a mutually exclusive fashion. In such references such as U.S. Pat. No. 5,184,564, there is disclosed a perimeter buoyant member for a personal watercraft such as a jet ski. However, in a multi-passenger boat (where passengers can substantially reposition themselves about the craft), the center of gravity of the entire boat and load substantially shifts from the center longitudinal axis of the boat. This shifting of the center of gravity must be countered with a buoyant lifting force. 
   Further, in certain situations, it is very desirable to store the boat in a compact region such as in the central storage area of a C-130 aircraft. In such a situation, it is very desirable to store a deployable boat where the boat requires a minimum volume. However, in certain situations it is desirable to immediately deploy the boat without the need to invest time for preparing it in any manner. Therefore, providing a boat that has the buoyant properties with rigid buoyant chambers that independently provides a vertical floating buoyant force from the inflatable perimeter members provides a more robust safe design. By deflating the perimeter inflatable members, the net width and overall volume of the boat is reduced and yet by providing the redundant rigid sealed chambers, the boat is seaworthy in this state. 
   SUMMARY OF THE DISCLOSURE 
   Described below is a multi-passenger boat comprising a rigid boat hull that has a center reference longitudinal axis with a forward region, a rearward region as well as port and starboard lateral regions. The boat hull further comprising a perimeter region where the perimeter region has a plurality of sealed rigid chambers separated by baffles where an outer concave surface is positioned laterally outward from the plurality of sealed non flexible chambers. 
   A perimeter inflatable member is provided that has an interior surface adapted to approximately conform to the outer concave surface. the perimeter inflatable member or the plurality of sealed rigid chambers independently provide a sufficient amount of buoyant force to maintain the rigid boat hull afloat. The perimeter inflatable member is adapted to be deflated to reduce the overall lateral width of the multi-passenger boat and the multi-passenger boat is adapted to be deployed and float when the perimeter inflatable member is deflated. 
   The inflatable flexible members further provide a lower surface adapted to provide additional support for the boat hull about the longitudinal axis whereby the maximum required load of the multi-passenger boat hull can be positioned at a medial lateral portion thereof and maintain stability about the longitudinal axis 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a side view of the chambered boat hull; 
       FIG. 2  is a top view of the chambered boat hull where a medial lateral portion is shown; 
       FIG. 3  is a longitudinal cross sectional view taken at line  3 - 3  of  FIG. 1 ; 
       FIG. 4  is a cross sectional view of the inflatable perimeter region; 
       FIG. 5  is a cross sectional view at line  5 - 5  of  FIG. 1  of the bow region of the inflatable perimeter showing the bra attached thereto; 
       FIG. 6  is a side view of the rear portion of the chambered boat hull; 
       FIG. 7  shows the inflatable perimeter in a partially deflated state narrowing the lateral overall width of the chambered boat hull; 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As shown in  FIG. 1  there is shown a multi-passenger boat  18  having a chambered boat hull  20  which in one form comprises a plurality of inner chambers positioned around the perimeter hull portion  28  as shown in  FIG. 2 . In general, the boat hull comprises a central region  22 , a bow  24 , a stern  26 , the aforementioned perimeter hull portion  28  and an inflatable perimeter  30 . 
   The chambered boat hull  20  has a central longitudinal axis  21  that generally runs from the bow  24  to the stern  26  (see  FIG. 2 ). For reference purposes the chambered boat hull  20  further has a lateral axis  23  and a vertical axis orthogonal to the longitudinal and lateral axis  21  and  23  respectively. 
   In one form, the chambered hull is substantially manufactured pursuant to the description of U.S. Pat. No. 6,520,107 which is herein incorporated by reference. 
   As shown in  FIG. 3 , the central region  22  comprises a lower wall  36  having a lower surface  38 . The lower surface  38  is adapted to engage the body of water which the chambered boat hull  20  rides upon. The lower wall  36  has a lateral portion  40  that is fixedly connected to the perimeter hull portion  28 . In one form, the perimeter hull portion  28  is comprised of a multi-creased perimeter wall section  42  as shown in  FIG. 3 . The multi-creased perimeter wall section has a lower portion  44 , and upper portion  46 , a laterally inward portion  48  and laterally outward portion  50 . 
   The lower portion  44  of the multi-creased perimeter wall section  42  has a first surface  52  and a laterally outward surface  54 . The first surface  52  is adapted to engage water traveling up the lower surface  38  when the boat hull  20  is planing along a body of water. The laterally outward portion  50  has a lateral indent region  56  where the upper lateral corner  58  and the lower lateral corner  60  extend laterally outward a greater degree than the laterally central region  62  as shown in  FIG. 3 . One form, the lateral indent region  56  is comprised of a multi-creased wall section  64  which comprises an upper crease  66  and a lower crease  68 . It should be noted that the outer concave surfaces positioned laterally outward from the sealed non flexible chambers need not be around the entire perimeter but a preferred form a substantial portion thereof. The various wall portions of the multi-creased perimeter wall section  42  define a rigid chamber  70 . 
   As shown in  FIG. 3 , the outer chamber wall  71  is adapted to define the rigid chamber  70 . Positioned laterally outward thereof is a secondary chamber  73  where the fasteners  114  and  134  are adapted to extend into this region in a fastening system as described below. It should be noted that the outer chamber wall  71  can be positioned in a variety of orientations, and in one form, the material to define the lateral end region  56  is welded to the outer surface of the outer chamber wall  71 . 
   A perimeter vertically extending member  80  is attached to the upper portion  46  of the multi-creased perimeter wall section  42  as shown in  FIG. 3 . In general, the lower wall  36 , the multi-creased perimeter wall section  42  as well as the vertically extending member  80  which is rigidly attached thereto comprise a laterally rigid portion  82  of the chambered boat hull  20 . The inflatable lateral portion of the boat hull  20  is indicated by the general section  84  in  FIG. 3 . As shown in  FIG. 4 , positioned in the inflatable lateral portion  84  is the inflatable perimeter  30 . The inflatable perimeter  30  comprises an inflatable membrane  90  having an attachment region  92  and a laterally outward region  94 . In general, the inflatable membrane  90  is comprised of a flexible type material that is relatively wear resistant and adapted to hold air or other gas therein the inflatable chamber region  96 . 
   The attachment region  92  in one form comprises an upper attachment member  100  which has a base region  102  that is attached to the inflatable member  90 . The base region  102  can be attached to the inflatable member  90  by way of an adhesion, stitching or other suitable method of attachment that are known in the art. The upper attachment member  100  has an extension  104  which in one form produces a loop with rod like material  106  longitudinally extending therearound the perimeter region of the chambered boat hull  20 . A fastening system  110  which comprises the longitudinally extending member  112  and a plurality of connectors  114  which in a preferred form are pop rivet type fasteners or the material indicated at  46  is tapped to receive a threaded fastener where the head region of the fastener is recessed in a frustoconical cavity of the longitudinally extending member  112 . It should be noted that the terms longitudinally extending are referred to in majority of the portions of the described regions relating to the inflatable perimeter  30 . However, as shown in  FIG. 2 , at portions near the bow  24 , the regions converge inwardly and only partially run longitudinally but still is designed to run longitudinally. A medial lateral portion is shown at  27  at approximately the location indicated at  27  which is an area between the far lateral portions  29  and the center axis  21  of the multi-passenger boat  18 . As discussed further below, the hull  20  is adapted to handle shifting of the center of gravity in situations where say all of the passengers go to one side of the boat for rescue operations or other reasons such as merely site seeing where an attraction is at one lateral side of the boat  18 . 
   Now referring to the lower part in  FIG. 4 , the lower attachment member  120  is similar to the upper attachment member where similar portions are attributed similar names and as such the description of the upper attachment member is relevant and provides the basis of description for the lower attachment member  120 . However, the general portions of the lower attachment member are now described where the base region  122  is fixedly attached to the inflatable member  90  by any suitable means. The extension  124  is adapted to have a lip region  126  which in one form is created by the rod  128  whereby the fastening system  130  comprises the longitudinally extending lower member  132  where a plurality of fasteners  134 , similar to that has fasteners  114 , restrict the distance between the longitudinally extending lower member  132  and the laterally outward surface  54  whereby the lip  126  cannot pass therethrough. Of course this is a similar fastening system as the upper fastening system  110 . 
   As shown in  FIG. 4 , the lateral indent region  56  defining an outer concave surface  57  of the perimeter hull portion  28  is adapted to receive the conical inflated cross-sectional outer surface of the inflatable member  90 . Therefore, the lateral indent region  56  is well suited to rigidly support the inflatable perimeter  30 . The inflatable perimeter  30  in general further comprises a lateral upward region  140  and a lateral downward region  142  as shown in  FIG. 5  where each of these regions have corresponding outer surface is that are adapted to engage the surface of the body of water in which the chambered boat hull  20  rides upon. It has been found that the outer surface of the lateral downward region  142  provides additional stability and support characteristics to smooth the ride in high speeds. It should further be noted that as shown in  FIG. 3 , the rigid chamber  70  provides enough buoyant lift whereby the chambered boat hull can remain afloat when the inflatable chamber region is not inflated. This is advantageous where it is desired to deploy the chambered boat hull  20  from a stored location such as a C-130 aircraft. When the chambered boat hull is transported in a confined space, it is desirable to reduce the overall size of the chambered boat hull  20 . Of course, the chambered boat hull  20  may have additional elements attached to it such as a center module, collapsible roof assembly, some form of motor and prop system, etc. It has been found that the chambered boat hull  20  comprising a rigid chamber  70  made from a material such as aluminum and an inflatable chamber region  96  cooperate to provide an extremely smooth boat that is particularly well adapted to corner and remain afloat in extreme conditions. Further, the chambered boat hull  20  is extremely safe whereby the redundant chambers provide a great deal of buoyant force to keep the boat afloat in the event the chambered boat hull  20  is damaged by external impacts from rocks and the like or “tore up” by small arm fire or other projectiles. 
   The inflatable member  90  further comprises an impact region  150  that is positioned in the laterally outward region  94  whereby the impact region  150  has impact resilient material  154  attached to the laterally outward region  94 . In one form, the fold over seal  156  is contained behind this impact resilient material  154  for protection purposes. The impact region  150  is particularly advantageous for low-speed and high-speed collisions of the chambered boat hull  20  against other objects on the water line in the body of water. For example, when the chambered boat hull  20  is pulling up adjacent to a ship at a relatively high speed, the impact region  150  is well suited for allowing a lower deceleration impact than a rigid hull. The nature of the inflatable member  90  is such that the cross sectional circular shape is adapted to transform to an oval like shape temporarily when an impact occurs whereby the lateral displacement of the chambered boat hull  20  takes place over a longer period of time reducing the felt impact. Further, the impact region  50  allows for a quieter impact in the event of a high-speed operation where operators contained on the chambered boat hull  20  are commandeering a dock or another vessel and desire to have a fast but quiet engagement. Further, in the event of defending a larger ship, having an impact region is advantageous where the chambered boat hull  20  is functioning as a patrol unit and deterring small vessels from a larger ship to prevent a catastrophe such as the USS Cole incident. It should be noted that in operation, in some forms, the inflatable perimeter member  30  is completely out of the water, not providing any buoyant lift particularly when the boat is planing. However, the lower surface  85  of the buoyant member  30  is in a proper position to engage the upper surface of the water to provide stability and support during say a high wave, cornering or a shifting of the center of gravity towards one lateral portion of the boat. It should be noted that the outer concave surfaces positioned laterally outward from the sealed non flexible chambers need not be around the entire perimeter but a preferred form a substantial portion thereof. 
     FIG. 5  shows a cross sectional view of the forward portion of the inflatable perimeter  30  where a protective bra  160  is provided. The bra has a lower region  162  which in one form is adapted to be fastened and interposed between the laterally outward surface  54  and the longitudinally extending lower member  132 . The protective bra  160  further comprises an upper lateral end  164  that is adapted to be fastened to a portion  166  with a rope or twine  168 . The protective bra  160  can be made of Kevlar or other wear resistant material. The bra is particularly conducive for protecting the front portion of the boat in the event of a front impact upon another vessel. Further, the bra is particularly advantageous in the event that a continuous wear is occurring upon the boat. For example in the event of a change in tide or a series of waves where the boat is docked to a non-floating dock and the boat oscillates in a manner to rub against the stationary abrasive dock material, the bra is adapted to have better wear characteristics and prevent damage to the underlying material. As shown in  FIG. 6 , laterally extending flexible members  170  can be provided that are attached to the laterally outward region  94  at one end portion and the other end portion is rigidly attached to the rigid portion of the hull at connection point  172 . The inflatable perimeter  30  further has a rearward extension  180  having a rubber bumper plate  182  that is well suited for wear and impact. It should be noted that the inflatable perimeter region is positioned laterally adjacent to the concave portion whereby fendering is feasible and reduces the amount of stress exerted upon the fastening portions f fastening the inflatable perimeter region to the rigid hull portion. In other words, by having the location of the fastening portions and upper and lower locations (as opposed to just a lower or upper portion), the inflatable perimeter has direct compressive contact with the concave portion in not producing a moment about either the upper or lower fastening regions. 
     FIG. 7  shows the inflatable perimeter  30  in a deflated state whereby the lateral width of the chambered boat hull  20  is substantially reduced in a deflated state. It is advantageous to have a chambered boat hull that can be deployed in such a deflated state and still be functional and have a sufficient amount of buoyant lift so the chambered boat hull  20  can remain afloat. As illustrated in  FIG. 7 , the inflatable perimeter  30  is substantially deflated and as can be seen in this figure, the lateral width  200  is narrower than the width  202  as shown in  FIG. 3 . Of course being in a deflated state, the width of the total lateral distance from the rigid portion of the chambered hull could compress to a distance as shown in  204  of  FIG. 7 . Therefore, it can be appreciated that numerous boats can occupy a smaller footprint area within a tight confinement when the inflatable perimeter  30  is deflated. The width of the inflatable perimeter  30  can be narrowed as much as 50% and in a more preferred form over 60% up to 80% of the inflated width. 
   Of course various modifications and alternative forms of the a chambered boat hull can be employed where specific embodiments thereof have been shown by way of example in the drawings and described above in detail. It should be understood, however, that such an enabling description is not intended to limit the invention to the particular form disclosed, but rather, on the contrary the intention of such disclosure and claims set forth below is to cover all modifications, equivalence and alternatives falling within the spirit and scope of the claims.