Bilge drainage system

[0002] Many power boats have a manual drain plug located in a through-transom hole in the transom, near the base of the transom and extending through the hull to the rearmost area of the bilge. As a boat undergoes normal usage, it inevitably takes on water which accumulates, and which ultimately works its way down to the bilge. The through-transom drain plug is designed to be removed when the boat is taken out of the water to permit the bilge to drain. For trailered boats, this is a primary means of draining bilge water, and the plug is removed nearly every time the boat is taken out of the water. Gravity will cause the water to flow out of the boat, and will be most effective when the boat is positioned with the through-transom hole at a point that is lower than the interior of the bilge. In larger or non-trailered boats the primary means for bilge drainage may be a bilge pump, although when the boat is hauled for storage, maintenance, or repair, it is common for the through-transom drain plug to be removed, both to drain any water that may be in the bilge, and to provide an exit for rain or other water that may collect in the interior of the boat during storage, maintenance, or repair.

[0003] A common method of sealing the through-transom hole during normal boat usage is with an external, threaded plug. When the boat is out of the water, the plug is easily accessible and can be removed using only a wrench. While this method of boat drainage is simple and easy, it has at least two major drawbacks, either of which has been experienced by many, if not most small boat owners at sometime during their lives. First, because the plug is not sealing the drain hole when the boat is out of the water, it must be inserted into the drain hole before the boat is launched. If is it not, the boat will immediately begin to take on water when launched, and the amount of water taken on will depend only upon how long the drain hole has been submerged before the condition is discovered. When the condition is discovered, the boat must immediately removed from the water, if possible, allowed to drain, and the manual plug inserted. If the boat has taken on too much water before the condition was discovered, it may not be possible to remove it from the water using the same means as were used to launch it, and more elaborate and expensive steps to remedy the condition must be used. In addition, when water reaches a critical level in the boat, electrical components and batteries may be adversely affected, and fuel, oil, and other materials may spill and cause environmental damage.

[0004] A second drawback to using the standard drain plug is that, in the event that the boat takes on water while afloat and away from land, the water cannot be drained through the drain hole, but must be emptied using an electric or manual bilge pump. Even though a boat planing through the water could theoretically drain its bilge through the drain hole, it is difficult if not impossible for the externally threaded plug to be removed during high speed planing. When a boat capable of high speed plaining does begin to take on water, it must rely solely upon its bilge pump to remove the water and alleviate a potentially dangerous condition. If, for any reason, the bilge pump is inoperable, such as a failure of the boat's electrical system, a merely inconvenient condition can quickly develop into a life-threatening one. Accordingly, there is a need for a bilge drainage system that can be manually operated from inside a boat while the boat is otherwise operable.

[0005] The bilge drainage system of this invention uses a permanent internally-mounted stopcock to provide an open through-transom drain hole that may be manually operated while the boat is riding on a plane. The planing motion of the boat orients the hull such that the base of the transom is at a point that is below the bilge. While planing, bilge water may be drained simply by opening the drainage hole. This means of drainage does not need electrical power or external access to the drainage hole, and requires only that the motor be running and the boat be capable of maintaining sufficient speed to reach a plane so that the water from the bilge may drain as a result of gravity or a pressure differential. The bilge drainage system may be included as a feature provided by the manufacturer in new boats, and may easily be retrofitted into existing boats.

[0006] FIG. 1 is a sectional side view of the bilge drainage plug of this invention.

[0007] FIG. 2 is an exploded view of the bilge drainage plug and the manner of its mounting in the transom of a boat.

[0008] In FIG. 1 it may be seen that a through-transom hole is located near the base of the transom 10. The external member of the bilge drainage system is a short pipe having a flange 20 mounted directly to the exterior surface of the transom using screws or some other suitable means for secure attachment to the transom. The interior surface 30 of the external member is threaded to receive a through-transom pipe 40 that extends through the transom and into the interior bilge area of the boat 50. Where the bilge drainage plug of this invention is installed as original manufacturer's equipment, the external member 20 and through-transom pipe 40 may be cast as a single unit. However, for retrofit installations, it will be necessary to tap the rear of the drain pipe of the external member 20 in order to thread a through-transom pipe 40 into it.

[0009] The through-transom hole is sealed on the inside using a resilient, non-corrosive compressible washer 60, a rigid washer of comparable size 70, and a flanged lock nut 80 that screws down on the threaded through-transom pipe. This installation provides not only a strong assembly that can withstand significant wear, tear and abuse, but it also seals the interior of the transom from leaching and other absorption of bilge water and degrading contaminants that may be in the bilge water, thereby prolonging the life and integrity of the transom in the area adjacent to the bilge drain system.

[0010] The through-transom pipe may then be extended for whatever length is necessary to make the interior end accessible for manual operation. In determining an appropriate length, however, it is also necessary that the end of the pipe must be located near the bottom of the bilge 50 so that water may enter the pipe when the boat is planing. At the interior end of the pipe a stopcock having a ball valve 110. A second lock nut 100 is tightened against the stopcock to prevent it from becoming loose through vibration. A handle 120 atop the stopcock permits manual operation of the valve.

[0011] An exploded view of the assembly is shown in FIG. 2. Threaded portions 130 of the 12 through-transom pipe 40 are used to secure the pipe to the external member 20, to secure the compressible 60 and rigid 70 washers against the transom with flanged lock washer 80, and to secure 14 the through-transom pipe to the stopcock 90, further secured with lock nut 100.

[0012] Enhancements and modifications may be made to the bilge drainage plug as desired to increase reliability, safety, or ease of use. For example, an electric motor with a disengaging clutch may be used to operate the stopcock with the manual handle being used only if needed as a backup. This configuration would enable the valve to be operated remotely by the boat operator whenever bilge water drainage is desired, so long as the boat is on a plane. Similarly, a float valve, water flow sensor, check valve, or other water-sensitive mechanism could be mounted externally or internally to ensure that the valve is closed, or to electronically close the valve, whenever the boat comes off the plane or otherwise slows sufficiently to allow seawater to flow back through the drainage plug. A manual, remote, or electronic remote valve status indicator may also be provided to signal the boat operator whether the valve is open or closed, and a physical locking mechanism may be placed over the manual handle to prevent accidental movement of the handle without first removing the locking mechanism. Other modifications or enhancements may be added to the invention as disclosed, and such modifications or enhancements will not depart from the scope and spirit of the invention as claimed below.