1. Field of the Invention
This invention relates in general to the field of closing devices useful in preventing water from passing to the chain locker via the hawse pipe of a marine vessel. Specifically the invention relates to a sealing device, which when installed in the hawse or chain pipe leading to the chain locker of a drilling vessel, will seal about the chain to prevent flooding of the chain locker during extreme list or storm weather conditions.
2. Description of the Prior Art
The prior art has provided both horizontal and vertical arrangements for the hawse pipe leading to the chain locker of a semi-submersible rig. Where the winch is located in the chain locker below the main deck, the top of the platform is left relatively clear and the overall center of gravity of the rig is advantageously lowered. If the hawse pipe is horizontally oriented, the hawse pipe opening may be low in relation to the water but, the rig may be susceptible to flooding during extreme list conditions or heavy weather.
In the vertical arrangement of the hawse pipe, a deck sheave and an underwater fairlead direct the anchor chain from an anchor to the vertical hawser pipe leading to the chain locker. Even with the vertically oriented hawser pipe, the chain locker is a potential rig destabilizing problem if it were to fill with water during extreme list conditions or heavy weather.
The prior art has not been able to solve the problem of providing a reliable sealing device to seal about the hawser or anchor chain and prevent seawater from flowing to the chain locker from the hawse pipe.
Prior art attempts to seal between the hawse pipe and the hawser chain have been unsuccessful due to the inability to position the chain relative to a ram-type closing device and due to the inability of other types of closing devices to conform to the highly irregular profile of a chain.