Proper sink drain

[catakate]

It looks like on my boat from far away I will need to fit a marine sink drain. What kind of a set-up would you recommend for a 22' boat, provided I could find it in UK?

Thanks!

[atoll]

1'1/4 bronze through hull fitting,,ball valve seacock,38 mm nipple,hose to underside of the sink fitting with 40mm tube outlet,2 hose clamps

you will need the correct size hole cutter and some sikaflex sealer,and maybe a blow torch to sweat the hose on the sink fitting.

[onestepcsy37]

or just put a large container under the sink with a hose into it. the kind of containers that laundry soap comes in, or kitty litter, are about the right size. cap it and dump it when you're done for the day.

don't make any more holes in your boat than you have to.

[catakate]

Thanks a lot for your input.
@atoll the sikaflex sealer hint is much appreciated.

[atoll]

thought i had a photo of the instalation i did last month,but only got one of before.
will try take a photo tommorow and post it to give you a better idea
have a look at the link below lots of good stuff on the refit i have been doing

http://www.cruisersforum.com/forums/...rew-59975.html

[catakate]

Originally Posted by atoll

have a look at the link below lots of good stuff on the refit i have been doing

http://www.cruisersforum.com/forums/f106/macwester-26-and-the-hina-ous-crew-59975.html

I had that on my list, just waiting for the time to do it at a slow pace.

I'm seriously thinking about creating a boat knowledge web portal! Invaluable info and knowledge are dispersed across many many threads here as well as all over the internet and we can lose all that knowledge when the bills for the hosting are no longer payed.

[atoll]

Originally Posted by catakate

I had that on my list, just waiting for the time to do it at a slow pace.

I'm seriously thinking about creating a boat knowledge web portal! Invaluable info and knowledge are dispersed across many many threads here as well as all over the internet and we can lose all that knowledge when the bills for the hosting are no longer payed.

no worries,lots of good info here and on cruisers wiki,and for the uk ybw.com

[wsmurdoch]

My Tanazer 22 has a 3/4" seacock in the hull. The sink drain reduces to 3/4" before it gets to the seacock. This is how the factory did it. The tubing is clear PVC, so I can see what is going on.

When I pulled out the sink stopper, the air in the drain hose between the sink and the seacock had nowhere to go, so the draining water ran (slowly) down the side of the drain hose which never filled. It remained full of air. I added a tee in the 1-1/4" drain line from the sink before the drain line reduced to 3/4". The drain came in one run of the tee and out the other. The branch of the tee was reduced to 1/4" and a piece of tubing extended up under the sink cabnet counter. That let the air out of the drain line so the drain line ran full, and he sink drained much faster.

My house has a similar vent under the sink after the trap. The vent goes to the roof. Why don't boats?

[My Pacific Seacraft has dual sinks. If both sinks are full of water and I pull one plug, that sink drains slowly. If only one sink is full of water and I pull its plug, that sink drains quickly (because the air in the drain line can get out through the empty sink, I think).]

[catakate]

Originally Posted by wsmurdoch

The branch of the tee was reduced to 1/4" and a piece of tubing extended up under the sink cabnet counter. That let the air out of the drain line so the drain line ran full, and he sink drained much faster.

English is not my native language and I do have some difficulties with technical terms... but I think you are referring to what an overflow drain does to any sink or bathtub. Put a plug to that and any air trapped below the draining water will slow the process...

Am I getting it right?

[sabray]

You should not need a vent line on a boat. Your house drains are tapped to sewer lines and have water loop traps. These vent pipes release the suction pressure and protect against back feed of sewer gas. your home as in fixed foundation sewer system has a well designed vent. Usually I have never seen a vent on a boat drain. Except anti siphon vent. We vent our holding tanks to allow for pressure difference when pumping into or out of the tank. Vent the fresh water tank so atmospheric pressure is maintained. 3/4 inch on a drain line is small.

[Marqus]

I see a comment above about trying to avoid drilling another hole in the hull.

I've seen a few sinks with two seacocks - one for a seawater supply to the sink, and the second for draining the sink.

Question: Is there a clever way to use a single seacock to do both - supply sea water and drain dirty water, keeping in mind that you:
1) need not do both simultaneously, and
2) that you want to avoid pumping up some old/dirty water again ?

[sabray]

Best to not try that. Let waste be. Don't suck it through expensive pump.

[Marqus]

Originally Posted by sabray

Best to not try that. Let waste be. Don't suck it through expensive pump.

Need to spare the pump, right.

But say you're using a benchtop hand-operated pump for the raw seawater supply, what are the practicalities (or non-practicalities) of merging the drain hose with the upwards feed hose just above the seacock?

Anyone have a working setup with a single seacock for drain and supply?

[wsmurdoch]

Originally Posted by catakate

English is not my native language and I do have some difficulties with technical terms... but I think you are referring to what an overflow drain does to any sink or bathtub. Put a plug to that and any air trapped below the draining water will slow the process...

Am I getting it right?

Yes. Start with water in the sink, the rubber plug in the drain, a few inches of air in the upper part of the drain hose under the sink, and water standing in the lower part of the drain line. Pull out the plug. The air in the drain did not bubble up through the water in the sink nor did it move down the drain hose and bubble out through the seacock. It remained in the drain line. The water draining from the sink ran down the side of the drain line around the air bubble. In my case the bubble moved down from the 1-1/4" part of the drain hose into the 3/4" part of the drain hose and greatly slowed the water draining from the sink. I could watch it through the clear vinyl tubing that the drain line was made from.

[jeremiason]

In my opinion, for a boat like yours, there is no reason to use bronze thru hulls...

Marelon will work fine... It is ABYC approved, is much lighter bronze, has no metal to corrode or be grounded and will be significantly cheaper.

Yes, there is the old salt argument that they will break under a shear load, but so far that hasn't been significant problem and most production boats are using them.