Patent Application
20130228118
The present subject matter relates generally to motorboats. More specifically, the present invention relates to a design for a small (approximately 20-36 foot), fiberglass, recreational, fishing, or sport-type motorboat that satisfies three important safety criteria simultaneously: selfrighting, self-bailing, and being unsinkable. The present subject matter further discloses a method for retrofitting motorboats to achieve the same safety criteria.
The majority of boating fatalities have little to do with bad weather or hazardous sea conditions. They typically occur in smaller, open boats on inland waters during daylight hours when weather and visibility are good, winds are light, and the water is calm. Despite these ideal circumstances, passengers fall overboard and many boats capsize, flood, or sink, resulting in over half of all boating fatalities.
Capsizing is when a boat turns on its side or turns completely over becoming disabled. The act of reversing a capsized vessel is known as righting. Accordingly, a vessel may be designated as self-righting if it is specifically designed to be able to selfright when capsized, i.e., return to upright position without intervention. Some boats are designed to be self-righting with minimal assistance.
Flooding (or swamping) occurs when a boat stays upright and fills with water. To prevent this from happening, safety features may be incorporated in the boat design allowing it to be described as self-bailing. Typically, these systems consist of drains that automatically empty water from the deck or cockpit, either by gravity, through scuppers, or by Bernoulli Effect. Other boats have openings that drain water into the bilge or a sump, both of which require an electric pump to evacuate the water.
Sinking is the catastrophic result that occurs when bailing is impossible and the boat becomes fully submerged and eventually totally sinking to the bottom of the sea. A variety of hull designs may be filled with a variety of different lightweight materials to prevent sinking and ensure the boat maintains level flotation and stability above the waterline in the event of an accident.
Safety features to avoid the dangers of boats capsizing, flooding, and sinking, and ultimately save lives, are typically integral to the designs of larger vessels (greater than 36 foot) as well as those of some smaller watercraft primarily intended as rescue or lifeboats, including rigid inflatable boats (RIBS). Ideally, motorboats in the recreational, fishing, and sport classes, which are more prone to such calamities due the increased likelihood of being piloted by less experienced sailors and their intrinsic instability resulting from smaller size, would also include features to address all of these concerns.
However, until now there have been no small fiberglass recreational/fishing motorboats in these categories that successfully fulfill all three safety criteria simultaneously; of being self-righting, self-bailing, and unsinkable, and are able to achieve these characteristics in an efficient, simple and cost effective manner based on a design concept. Accordingly, a need exists for a motorboat design as described and claimed herein.
The small motorboat design disclosed herein provides means for achieving the three important safety criteria of being self-righting, self-bailing, and unsinkable. All of these characteristics are addressed through an integrated simplified method, and without complicated or expensive equipment, thereby reducing the cost of manufacturing the boat. The present subject matter further discloses a method for retrofitting motorboats with the tools necessary to achieve being self-righting, self-bailing, and unsinkable. It is important to note that while the primary embodiment is described with reference to a small recreational motorboat, the concepts taught herein may be applied to boats of nearly all sizes and categories.
Various embodiments of motorboats may achieve the advantages of the innovative methods provided herein. In one example, a 23-foot, fiberglass motorboat, intended for recreation, fishing, or sport activities, simultaneously fulfills the three safety criteria of being self-righting, self-bailing, and unsinkable. An innovative design is provided in which the volume and placement of buoyant material is calculated and integrated into the hull bottom and sides, making the boat unsinkable and self-bailing. The hull design, unique weight distribution strategies, and a buoyant roof element (e.g., shade canopy, bimini top, targa top, enclosed cabin, etc.) collectively function as a system producing the boat's ability to self-right without external power, equipment, or assistance.
A stability analysis process may be used to design, construct, and/or retrofit boats to improve the boat's ability to be self-righting, self-bailing, and unsinkable. In one example, the stability analysis method includes calculations and testing as provided in the following steps:
In addition to the weight incorporated into the low middle portion of the boat, and the buoyant material incorporated into the bottom and sides of the hull, the self-righting characteristics of the boat may be improved by providing a buoyant roof element or similar elevated buoyant structure designed to increase the height of the righting arm (a notional lever through which the force of buoyancy acts expressed as the horizontal distance between the center of buoyancy and the center of gravity).
Unlike other small motorboats in the recreational, fishing, and sport categories that may be self-bailing, unsinkable, or in some cases both, the motorboat disclosed herein is designed to be not only self-bailing and unsinkable, but also self-righting.
An object of the present invention is to provide a small motorboat that is not dependent on any complex external equipment or systems for its self-righting ability. Providing a weight equal to forty percent of the unloaded hull situated as low as possible in the middle third of the boat along its length contributes to, but is not solely responsible for, this function.
For small, open, and outboard powered boats (typical of the boats intended to benefit from the subject matter disclosed herein), additional force is necessary to increase the height of the righting arm and reestablish the static and stable condition where the center of gravity and the center of buoyancy are aligned vertically. To that end, a buoyant roof element (e.g., a shade canopy, bimini top, targa top, enclosed cabin, etc.) is a design feature (whether original or retrofit) that helps to provide the force needed to initiate the self-righting act.
It is another object of the invention to provide a small motorboat with a deck or cockpit that is self-bailing, without the use of electrical or manual sump/bilge pumps, based on its novel hull concept. At this point it is vitally important to clarify and document an issue related to the definition and application of the “self-bailing” characteristic.
In most of existing motorboats, self-bailing means the ability of the boat to clear its deck from limited amounts of water. The word “limited” here is key. If the amount of water happens to be more than a certain volume, and its weight happens to drop the hulls scuppers (the openings on the deck, usually on the sides, that drain the water back to the sea) below the waterline, then the scuppers will cease to drain water, and may become a source of incoming water, thus making a hazardous situation even worse. This usually happens in the uncommon, yet catastrophic, event of the boat being “swamped,” i.e., when a huge amount of water fills/floods the entire deck within a very short duration, typically caused by a single large wave. The sudden overwhelming weight of the water causes the hull to sink (inches or feet), thus leading to the situation described above. Even boats with the most powerful bilge pumps will not be able to cope with this situation. The totally flooded boat then becomes very unstable and liable to capsize. At best, even if the flooded boat remains upright, and now the self-bailing ability lost, the deck will remain full of water, thus exposing the passengers to the “elements,” i.e., the water, wind and other materials slushing inside the boat, which contributes to morbidity/mortality due to falling overboard and hypothermia. In addition, when flooded some of the areas of the boat are typically inaccessible and thus functionality becomes limited, making passengers unable to cope with the disaster.
By contrast, the boat design provided herein ensures all water from the deck will be bailed out, even if the boat is swamped, thus leaving the boat floating, stable, and functional and the passengers protected from the elements. The design also enables the boat to remain stable in the case in which there is a major hole at the bottom or sides of the hull due to an accident such as striking a reef or other object.
In one example, the boat includes: a hull including a deck at the waterline dividing the boat into a lower portion below a waterline and an upper portion above the waterline and a centerline defining the separation between the starboard side and port side; an additional weight equivalent to approximately forty percent of the weight of the hull located within the lower portion of the hull approximately along the centerline of the hull; a series of scuppers located in the upper portion of the hull; a buoyant element located above the upper portion of the hull; and buoyant material placed within the lower portion of the hull, the amount of buoyant material having a buoyant force approximately equal to the weight of the boat, including the hull and additional weight, plus the weight of a volume of water required to completely fill the hull. The boat may be a fiberglass recreational motorboat that is approximately twenty-three in length. Of course, the principles taught herein may be applied to a wide variety of boats.
The additional weight may be located along the lowest internal section of the hull along a central third of the centerline. The scuppers may be located approximately adjacent to the waterline on the upper portion of the hull. The buoyant element may be attached to and extend above from the hull and may be a buoyant shade canopy, a buoyant bimini top, a buoyant targa top, a buoyant cabin, or another buoyant element. The deck may further include a partition located along the centerline of the hull separating the deck into two channels.
The buoyant material may be located along the bottom and sides of the lower portion of the hull and may be a closed-cell foam, air sealed within one or more air-tight compartments, or another buoyant material.
The method of designing a self-righting, self-bailing, and unsinkable boat may include the steps of: (a) determining the center of gravity of a boat including a hull; (b) measuring the weight of the loaded boat; (c) identifying the preliminary waterline; (d) calculating the equivalent weight of the total volume of water required to completely fill the hull; (e) determining the waterline when the hull is filled with water; (f) incorporating an additional weight of approximately forty percent of the weight of the unloaded hull along the middle third of the boat along its length; (g) calculating the total weight of the boat including the weight of the loaded hull, the weight of the water calculated in step (d), and the additional weight added in step (f), and dividing the total weight by the buoyant force of the buoyant material to be used to determine the volume of buoyant material required to keep the boat afloat in the event it becomes completely flooded; (h) distributing the calculated volume buoyant material throughout the bottom and sides of the hull; (i) determining the optimum location of the buoyant material; (j) providing a plurality of scuppers above the waterline of the hull; and (k) providing an elevated buoyant element above the hull.
The step of determining the center of gravity of a boat may include determining the center of gravity of the boat both in and out of water. The step of determining the optimum location of the buoyant material may include iterating the design process by repeating the method varying the location of the buoyant material and comparing the results to identify the optimum location of the buoyant material. The method may further include the step of providing a deck located at the waterline of the hull including a partition located along the centerline of the hull separating the deck into two channels.
The partition along the deck (at the centerline of the hull) separates the deck into two channels. While the partition may act as a seat and/or a compartment for storage, it is primarily beneficial in that it serves to counteract the free surface effects by minimizing changes in the center of mass of the boat when free water sloshes towards the port or starboard sides, ultimately making the boat more stable, minimizing its resistance to being self-righting, and minimizing the risk of capsizing.
The method may applied to the initial design process of the boat or may be applied to retrofitting an existing boat.
It is another object of the invention to provide a small motorboat that is unsinkable due to its hull design, the application of calculated weight distribution strategies, and optimally located buoyant material.
Many existing boats claim to be unsinkable because the “nose” or some other small percentage of the boat may remain above water in catastrophic events, leaving the passengers to hold on to the floating portion of the boat, while floating in the water themselves. It is another object of the invention, to provide a boat design that maintains a fully floating stable hull, clear of water under otherwise catastrophic conditions.
It is another object of the invention to provide a motorboat that incorporates the safety criteria of being self-righting, self-bailing, and unsinkable and can also be simply and efficiently manufactured with reduced cost.
It is a further object of the invention to provide a methodology for applying the safety criteria of being self-righting, self-bailing, and unsinkable to both new and existing small motorboats.
Additional objects, advantages, and novel features of the examples will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following description and the accompanying drawings or may be learned by production or operation of the examples. The objects and advantages of the concepts may be realized and attained by means of the methodologies, instrumentalities, and combinations particularly pointed out in the appended claims.
The drawings depict one or more implementations of the present subject matter by way of example, not by way of limitation. In the figures, the reference numbers refer to the same or similar elements across the various drawings.
While the method 100 shown in
Turning back to
As described above with respect to method 100 described in reference to
The volume of buoyant material 12 to be used is calculated by dividing the total of the weight of the loaded hull 20 (including the motor, tanks, equipment, etc.), the weight of the volume of water required to fill the hull 22, and the weight of the additional weight 18 (described further herein) by the buoyant force of the buoyant material 12. In a preferred example, the buoyant material 12 is a closed-cell foam, though it is understood that various buoyant materials 12 may be used, including air sealed within one or more air-tight compartments.
The preferred location for the placement of the buoyant material 12 is generally along the bottom and sides of the hull 22. However, it is understand that the exact details of the placement of the buoyant material 12 may be further improved by an iterative testing and revising process applied to each individual hull 22 and boat 10 design.
Turning back to
The proper location of the scuppers 14 is very important to the self-bailing properties of the boat 10. Using scuppers 14 that remain above the waterline 16, even when the hull 22 is entirely filled with water, ensures that there are no circumstances in which the scuppers will not assist in bailing the boat 10. In addition, using passive scuppers 16, as opposed to active pumps, ensures that the boat 10 will remain self-bailing without concern of electrical or mechanical failure. In addition, it is recognized that by locating the deck 32 approximately at the waterline of the loaded hull 22, and the scuppers 14 directly above the deck 32, the scuppers 14 may perform optimally to enhance the ability of the boat 10 to be self-bailing.
As described above with respect to the method 100 described with reference to
As further shown in
In addition to the additional weight 18, the elevated buoyant element 20 assists in improving the self-righting characteristics of the boat 10 by increasing the height of the righting arm. In the example shown in
In addition to the features described above, the boat 10 may be adapted to combat the free surface effects, and related slosh dynamics effects, that occur when water is present on the deck 32 or in other open areas of the boat 10. If not counteracted, the free surface effect can cause the boat 10 to capsize. In brief, the free surface effect is the effect caused by free water moving within the boat 10 in response to changes in attitude of the boat 10. As the boat 10 tips in one direction, the free water flows in that direction, altering the center of mass of the boat 10 and counter-acting any righting effect.
Turning now to
It should be noted that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modification may be made without departing from the spirit and scope of the present invention and without diminishing its advantages.
