Bilge pump size

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Neil Gordon
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Re: COCKPIT DRAINS

Post by Neil Gordon »

Oswego John wrote:A dozen rainwater drains won't be of any help if the drains and thru-hull outlets are beneath mean sealevel.
I agree about manning the pumps and getting the water out. But as for drains, it matters not if the thru-hulls are located below the water line. Mine are on the CD28, as are the seacocks for the sink and the head.
Fair winds, Neil

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Tim Mertinooke
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Post by Tim Mertinooke »

OJ, thanks for the information. I have decided through research and with talking to knowledgable people at my club last summer to increase the drain size to 2" and to use real seacocks like the ones I showed in my previous post. Going from 3/4" to 2" alone should make a significant difference even if I stick with the 2 drains for now. You answered my previous question as well about needing another two thru-hulls and seacocks if I were to increase the drain number to 4. Greg Ross told me he was once pooped in his Ty up in his home waters of P.E.I. and that the two little drains drained the cockpit quicker than you would think. Encouraging news, but I'm still being cautious by increasing the size. Point taken about mean sea level and what would happen if the tops of the drains were below that level. I think I'll look into the electric bilge pump in the cockpit like Winthrop suggested. As for a bucket? I carry two. You know the old saying, "nothing moves faster than a man with a bucket in a sinking boat." Thanks again for your insight. Tim
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A Dozen Rainwater Drains....

Post by Oswego John »

Hi Neal,

Did the snow get to Beantown yet?

As for the drains, the context of the paragraph was about a following wave flooding the cockpit up to the coamings.

The thought behind my statement implied that water will seek it's own level. If sea level is above the sole drain(s), which are above the thru-hulls, there will be no gravity flow out of the boat. Without some type of check, there will probably be some reverse flow back into the cockpit.

I think that I mentioned that this was under gravity pressure. However, there would be positive flow out from the cockpit through the same system if the water to be drained was under pressure, either from a piston or a rotary type pump. Also,the positive flow will be present if the cockpit surface water is higher than sea level, but only until it is equal with sea level.

Without seeing it, your boat's head discharge is probably ejected by means of pump pressure out of a below surface thru-hull and that the drain water in your sink, under normal conditions, has gravity flow discharge because it is above sea level.

The thing to remember is that without some form of one way check, water can, under adverse conditions, flow into the boat and that's not good.

Sorry to mislead you,
O J
Keep that snow shovel waxed up.
Neil Gordon
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Re: A Dozen Rainwater Drains....

Post by Neil Gordon »

OJ,

Yes, for sure, if the drains are below sea level, the water in the cockpit won't drain out. Location of the seacock though, matters not (we're presuming the seacock is below the drain, right?)

My sink is above sea level, except at extreme heeling. The seacock, is below. With the seacock open, the norm is water, up to sea level, in the drainage hose.

The same for the head except that there's a loop from the head to the seacock. (The head is just above the waterline and easily below it on a starboard tack.)

Yes, nice snow in Boston, although the city proper, being right on the water, got less snow than just a bit inland.
Fair winds, Neil

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Post by winthrop fisher »

:) i sent you the pitures of both... talk to you later....winthrop
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