To cock or not to cock.

woodster · Mar 11, 2011

Snotter said:
What is the collective opinion on sea-cocks on cockpit drains? My old pearson had glass tubes bonded to the hull that went straight to the cockpit. My Morgan OI (center cockpit) utilizes sea cocks which I never close. A backing block under one of these sea cocks turned musshy because of a leak in a battery box (since corrected). I will be moving the location of the cockpit drain through the hull to accomodate the installation of a genset. Should I buy a new sea cock (don't want to use the old one) or glass in a tube with epoxy?

Ya'll are keeping my honest this spring.

i have the glass tubes that you speak of on my s-2 for cockpit drains...they go below the water line and have no seacocks...they seem a little small to me about 1 1/4 inches i think ...also the bilge waste line was feeding out to the starboard one and the manual bilge pump was feeding the port drain....

i dont think i want seacocks on my cockpit drains for any reason...as they could be left in the closed position and resulting in sinking my boat in a bad rain storm...i will also be seperating the bilge pump exits to stand alone...my thinking is that each system should be on its own ...as to be able to monitor there operation at any given time.....may be a bit of over kill but i will feel a lot better this way.......

regards

woody

Roger Long · Mar 11, 2011

No seacocks but the through hulls should exit above the waterline if they are hose and not structural glass.

bria46 · Mar 11, 2011

I agree with Roger. Thru Hull fitting without seacocks should be mounted NO LESS THAN 6 INCHES above the waterline

Maine Sail · Mar 11, 2011

If you want to follow the industry guidelines, and the thru-hulls can go below water or are below it when static, then a Seacock is the proper procedure.

I would use a flanged adapter as opposed to a seacock then when the valve dies from lack of use you can easily replace it.

ABYC:
"27.5.1 All piping, tubing, or hose lines penetrating the hull below the maximum heeled waterline, shall be equipped with a seacock to stop the admission of water in the event of failure of pipes, tubing, or hose."

Roger Long · Mar 11, 2011

bria46 said:
NO LESS THAN 6 INCHES above the waterline

Mine are closer than that but the top of the bronze necks are about 10 inches above the waterline. A fitting like that which is dry most of the time is at virtually zero risk of failure. Installation of seacocks wouldn't have been possible because the drains are too short. Better to have them quick draining and be able to push a stick through to clear them than to relocate them just to comply with ABYC.

Left picture is the original, really stupid design. That's clear plastic hose leading to the gate valves that couldn't be reached!

tommays · Mar 11, 2011

A lot of older boats like the C&C 35 MARK I have it as the only way to drain the cockpit and you just have to keep the hsoe and clamps in good shape

We also have a plug at each one even though getting to two of them is pretty hard

Ron20324 · Mar 11, 2011

Seems to me in an earlier question it was suggested to cross the drains? When heeled, the low drain in the cockpit would then be out of the water on the high side. Seacocks seem like a good idea, too. For dual-use, you may want to use the cockpit as a bathtub:dance:

Maine Sail · Mar 11, 2011

Ron20324 said:
Seems to me in an earlier question it was suggested to cross the drains? When heeled, the low drain in the cockpit would then be out of the water on the high side. Seacocks seem like a good idea, too. For dual-use, you may want to use the cockpit as a bathtub:dance:

This is very standard practice and works well if your lee side cockpit level scupper goes below water when heeled. Not all do so not always necessary.

Roger Long · Mar 11, 2011

Ron20324 said:
Seems to me in an earlier question it was suggested to cross the drains?

If you think the drains may ever have to empty a boarding sea from the cockpit, better to have them as short and straight as possible.

Something to consider is to have small drains that deal with just rainwater and one or two large straight drains that will let the main weight of a water from a boarding sea out. These don't have to dry the cockpit so can end well above the waterline and where you have more freedom in routing. Cockpits that drain from the front end are a good candidate for this kind of arrangement. Rainwater drains forward, big drains aft.

catsailor · Mar 11, 2011

Not discussed...

Can the cockpit floor move relative to the hull? There may be differences in how the two structures are designed. If the cockpit floats and moves a bit and FRP tube replaces a hose, you may create great stress. This is one of the reasons boats use more hose than pipe.

Roger Long · Mar 11, 2011

catsailor said:
If the cockpit floats and moves a bit and FRP tube replaces a hose, you may create great stress.

That's what "structural glass drains" means. They are installed so as to support the cockpit and properly transfer the stresses to the hull.

Good point though that retrofitting rigid glass tubes in a situation where hose was originally intended needs to be done with careful design.

Maine Sail · Mar 11, 2011

Snotter said:
Maine Sail, thanks for providing the ABYC quote. I should have thought to look at the ABYC literature. What is a flange adapter?

The Groco Flanged Adapter is the best marine invention since sails. It is a seacock flange base with proper threads on top (NPT) for a bronze ball valve and NPS threads below for a thru-hull. It through bolts or lags to the backing block or hull and remains permanent. When the valve dies, as they often do, you simply un-thread it and put anew one on. Takes about ten minutes and no haul-out necessary!

When a seacock like this seizes you need to excavate the whole kit & kaboodle, not with a flanged adapter. All the strength of a flanged seacock but not all the hassle. And they often don't cost any more than doing just a flanged seacock.

Tim R. · Mar 11, 2011

Ron20324 said:
Seems to me in an earlier question it was suggested to cross the drains? When heeled, the low drain in the cockpit would then be out of the water on the high side. Seacocks seem like a good idea, too. For dual-use, you may want to use the cockpit as a bathtub:dance:

Crossed is good but make sure the hoses have no low spots when the boat is level. If the hose has a dip that is below the seacock, water and other debris can collect in there and it will dump out into the cockpit when you heel or it will clog and you have no drainage causing water to get into the cabin if left for long enough.

Roger Long · Mar 11, 2011

Maine Sail said:
The Groco Flanged Adapter is the best marine invention since sails.

You can say that again. (Well, maybe not quite "sails" but close.)

The top of the ball of my holding tank pump out through hull is badly pitted. I you hadn't mentioned these adapters when you did, I would have put in a seacock and been facing a big job now instead of a few minutes with a pipe wrench. It looks like I'll be doing this every 3-4 years so it's great to have it easier.

The one possible quibble is that the threaded neck of the adapter is a lot thinner than the heavy cast body of a seacock. If there is any significant corrosion going on, the adapter won't last as long. If there is that much current flowing around your boat though, you've got other problems. Still, the adapters should be inspected more frequently.

Maine Sail · Mar 11, 2011

Roger Long said:
You can say that again. (Well, maybe not quite "sails" but close.)

The top of the ball of my holding tank pump out through hull is badly pitted. I you hadn't mentioned these adapters when you did, I would have put in a seacock and been facing a big job now instead of a few minutes with a pipe wrench. It looks like I'll be doing this every 3-4 years so it's great to have it easier.

The one possible quibble is that the threaded neck of the adapter is a lot thinner than the heavy cast body of a seacock. If there is any significant corrosion going on, the adapter won't last as long. If there is that much current flowing around your boat though, you've got other problems. Still, the adapters should be inspected more frequently.

Depends upon brand. I have measured many and the flanged adapter is as thick or thicker than many of them. Surprisingly it is even thicker than some Spartans and a lot thicker than most thru-hulls of which many boaters and builders slap a ball valve onto...

Oh and they are 85-5-5-5 bronze so you will be hard pressed to see these fail like the cheap, crappy European DZR1 stuff that has nearly 30%+ zinc. I have seen 85-5-5-5 Spartans at 35+ years old clean up to just like new with zero corrosion..

Merlin Clark · Mar 11, 2011

Maine Sail said:
The Groco Flanged Adapter is the best marine invention since sails. It is a seacock flange base with proper threads on top (NPT) for a bronze ball valve and NPS threads below for a thru-hull. It through bolts or lags to the backing block or hull and remains permanent. When the valve dies, as they often do, you simply un-thread it and put anew one on. Takes about ten minutes and no haul-out necessary!

When a seacock like this seizes you need to excavate the whole kit & kaboodle, not with a flanged adapter. All the strength of a flanged seacock but not all the hassle. And they often don't cost any more than doing just a flanged seacock.

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Another impressive display of craftsmanship!