Gate Valves

chris20636 · Nov 3, 2006

Chris:

With the new technology in valves, gate valves have no place as seacocks in
any boat. Too much can happen! Imagine that if the handle separates from the
gate stem while you are taking on water, you are in deep doo-doo!

In my mind, only good, high-quality ball valves are to be considered, that
are designed for just that purpose. They must be well-mounted, as well, so
that a piece of heavy material, loosely stowed, in a rough sea will not break
them off. Also, ball valves can be shut faster than gate valves.

The extra expense paid for this is long forgotten while you enjoy the
security of knowing your seacocks will not fail you.

Happy Sailing................Ed

alan_critchlow · Nov 3, 2006

Hello Chris. These must be the supply 1/2 " and 3/4". No problem. Use
ball valves. I had thought that these were metric. But seems that pipe
threads are the same in metric. (Except for the odd English BSP)

If you take off the gate valves on the 1 1/2" drains you will break
the throughhull. The smaller through hulls seem to have less problems
with corrosion Before you start buy new throughhulls and seacocks. If
the boat has sailed in saltwater you will notice the through hulls are
pink where they broke. They have dezinked from electrolysis.

Alan Critchlow V 1639 Voila

pjacobs55 · Nov 3, 2006

I'm about to replace all the old thru hulls and gates valves in Sin
Tacha, which I believe are the originals. They're all functioning
but the head waste valve is weeping a bit and I was afraid to put a
wrench on it until the boat was on dry land.

I'm using bronze hardware (Groco), as the plastic (Marelon) hardware
was about the same price.

Below is a link to Groco's thru hull installation recommendations,
with some interesting information on different types of pipe thread.

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www.groco.net

Hope this helps, and good luck with your project.

Peter
#1331 'Sin Tacha'

pelagicasd · Nov 4, 2006

Just to make a suggestion. Tie wooden bungs to each thru-hull. They come in
a variety of sizes. They should be big enough to fill the hole the valve
goes through and small enough on the tapered end to fit the inside of the
valve. West Marine sells an assortment for around $10.00. Work the,
frequently as barnacles can build up inside an "glue them" open. Walt
P.S. Don't mount them to the hull directly, use a wooden backing board
between them and the hull. Also be careful of the sealant. Don't use
anything which can't be seperated later.

o2n7dcolin · Nov 6, 2006

Chris I replaced all the thru hulls a few years back. They were all metric sizes and I replaced with the standard 1/2", 1" etc NPT pipe thread sizes. (Standard in North America !). You may have to enlarge the hull holes in some to allow this. Easily done with a round file. Just take it slow and keep checking fit. Head overboard for sure unless you want to adapt to 1 1/4" NPT and not use the usual 1 1/2" NPT.
When I first obtained V-703 she had NPT thread valves forced onto the metric thru hulls. This meant in some cases that there was only one turn of thread connecting the valve and thru hull. Although the diameter seems close the thread per inch and no doubt the thread angle are different, resulting in the binding after about one turn. Colin V-703, Isis...

Gate Valves

sabre28mk1

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chris20636

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alan_critchlow

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sabre28mk1

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pjacobs55

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pelagicasd

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o2n7dcolin

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sabre28mk1

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