Cockpit Drains (former email exchange)

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August 14, 2010 at 00:33 #4271
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Rainshadow said:
As new owners of our Nic 38, I’m very curious about this comment:”Cockpit drain seacocks on Voltair will be OFF from now on, and we will drain rainwater and other incoming to the bilge and pump it out from there.”
We are considering changing the whole arrangement so there would be larger drain holes in the cockpit sole, and properly crossed lines through the engine room to larger thru-hulls. Have others found this to be a bad idea? We did notice that the cockpit sole seems to be rather close to the waterline…

John Kingsley responded:
Hello Marilyn – there has been possibly thousands of words ofcorrespondence in this group about cockpit drains in the last year or so! Before we bought it, our yacht was operated for 10 years as a DOT approvedskippered charter yacht, and two of the many things the owner had to do inorder to comply was to fit 12″ high washboards to the companionways and to”fireproof” the pipes joining the cockpit sole drains to the through-hulls(since an engine fire would otherwise melt the pipes and sink the boat). Idon’t know if any other owners have done these things. The owner at thetime put glass-wool wrap around the plastic pipes, and put the tallwashboards away behind the settee berth. They do fit, but were never used. So if you do that, and you don’t mind half a ton of wave sitting in thecockpit and draining very slowly through the tiny holes in the corners backinto the sea, then this is one way to go. However, we can pump the waterout much quicker once its in the bilge than it will run out through thedrains, and since we feel this wave is mainly going to end up there anyway,finding its way through the side lockers and louvred vent below the wheeldown into the bilge, while dripping all over the alternator and engine, wethink we might as well hasten the procedure, and get it there as quick aspossible, and then get rid of it as quick as possible. We are not planning to cross any big oceans, but if you are, we are notsure if our solution is a good one, as serial waves would eventually causethe boat to sink, especially if the electric bilge pump failed, which islocated in the engine room. It would be much better to have huge 3″diameter drains in both sides, leading to 3″ holes on the waterline, but wesuspect that if you actually did that, you would find a lot of water cominginto the cockpit when heeled, while if you crossed the pipes over, no waterwould drain out. If the cockpit roof/sides/screen carried away completely,and waves were coming aboard one after the other, then I guess you probablyneed to completely seal the cockpit, while allowing it to drain to seahowever slowly, and let the surplus slop overboard as the boat heels. However, we did a calculation (and I can’t remember the numbers) but itwent something like….. 1 ton of water (= 1 cubic metre = half-fullcockpit) on board causes the boat to sink in the water by 1 inch. If thiswater is in the cockpit, and there are no leaks from the cockpit to thebilge, and the cockpit drains are open, it will eventually drain away. Ifthe water is in the bilge, and the cockpit drains are open, the boat willbe lower in the water and the sea will come IN through the cockpit drainsand sink the boat. This is made worse if you are in fresh water with lowerbuoyancy, or if the sea water is aerated. So various owners have fittedone-way valves to prevent this. The valves reduce the water flow rate goingout, and do not 100% stop it coming in, so we don’t like the idea ofleaving the yacht unattended for long periods with the draincocks open, incase rain or prop-shaft leakage causes ingress into the bilge, which sinksthe yacht when the cockpit drains go below sealevel. Probably you will get advice from the other owners – this is just how wesee it, as mainly coastal sailors, who are not that good at puttingwashboards in slots when we should. The problem is caused by the very lowcockpit floor, and you can’t do much about that I’m afraid. Next boat I buywill be different! Do copy me in on your ideas and experiences: I’m notsending this to the whole group as I think they may already have heardenough on the subject! Regards, John Kingsley

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