Coffer dam around skin fittings...?

MYStargazer

MYStargazer

Well-Known Member
Joined
5 Jan 2006
Messages
1,379
yachtstargazer.wordpress.com
My boat tends to live in the water all year around. I was reading about worries about frost-damaged seacocks, etc, which got me thinking...

As my boat's bottom is quite flat, why not build coffer dams around the seacocks, coming up, say 2" above the waterline?

They'd be made from marine ply and glassed-in, with enough room to open and close the cock, and get a stubby screwdriver in to check and tighten the jubillee clips if need be.

Can anyone see a downside to this idea...?
 
I think it's unnecessary. A boat afloat in a typical UK winter is highly unlikely to suffer freezing of the seacocks.
 
image.gif
wufojs.gif
 
Would work fine, but you lose a lot of locker space so most people consider the tradeoff not worth it. Remember you'll also need to bring the hose up and over the top of your dam, so the whole contraption will be quite large.

It's not uncommon on steel boats to bring welded-in steel pipes up above the waterline before adding the seacock on top, which is a somewhat similar principle.

Personally I do have plans to build a dam around my log transducer, but that's more about containing what comes in when the plug is pulled for cleaning rather than defending against sudden failure - and mine is unlikely to come anywhere near the waterline. The seacocks I'm quite happy with as they are.

Pete
 
Yeah, around the impeller, the main thing is to make it large enough to get your sponge in... Unfortunately most boats have the cabin sole below waterline to maximize headroom, so it is not possible to bring a coffer dam up high enough to ensure flotation.

Rob.
 
rob2 said:
Yeah, around the impeller, the main thing is to make it large enough to get your sponge in... Unfortunately most boats have the cabin sole below waterline to maximize headroom, so it is not possible to bring a coffer dam up high enough to ensure flotation.
.
Click to expand...

I could, because my transducers are in a locker, but I don't think I will. I'm going to go up just high enough to clear the top of the transducer, as I can then fit a lid to prevent it getting damaged by stuff in the locker.

As for sponges, my plan was to use a half-litre plastic syringe which I have knocking around in the shed. A quick slurp or two with that (and squirt out into the galley sink) should see the space more or less dry.

Pete
 
I agree with the OP if the architecture of the boat suits - as his appears to...
I've already done the one for the log impellor - not above waterline- just big enough to contain the sploosh when cleaning.
My boat has already got lots of built-in coffer dams that make location of a leak easy rather than filling the bilge and requiring talcum powder to trace the source, so it would be logical to have them above the waterline where it didn't impact other functions.
BTW, stringers are magic for isolating fresh from salt without the tingle tongue test...
 
pvb said:
Maybe I've misread the thread you've linked to, but didn't it refer to valves freezing whilst the boats were ashore?
Click to expand...

I think it did, but the valve doesn't 'know' whether it's ashore or not, does it? Wouldn't this be relying on the water being a few degrees warmer?

If ashore, what if a small crack developed which was just enough to allow a small but constant leak when put back into the water? Or a sudden total failure later in the year?
 
Fitzroy said:
I think it did, but the valve doesn't 'know' whether it's ashore or not, does it? Wouldn't this be relying on the water being a few degrees warmer?

If ashore, what if a small crack developed which was just enough to allow a small but constant leak when put back into the water? Or a sudden total failure later in the year?
Click to expand...

You started this thread by saying "My boat tends to live in the water all year around. I was reading about worries about frost-damaged seacocks,...". I offered the opinion that "A boat afloat in a typical UK winter is highly unlikely to suffer freezing of the seacocks.". If you now want to embark on a catalogue of unlikely "what if" scenarios, you'll never ever enjoy your boat.
 
I do not think it does. Managing your boat such that realistic risks eliminated will allow worry free enjoyment. The question you have to ask is the risk of a seacock freezing and bursting reasonably probable in the conditions that you keep and use your boat in? Up here in Scotland I have kept my yacht afloat where the seawater froze, I also manages a charter fleet some time ago and the marina waters froze as well (I am talking a cm of ice, not Sweden/Norway levels of freezing). In all these years there has never been any damage to seacocks due to ice. There has been frozen fresh water pipes on board. On my own yacht, I experienced burst water pipes when she was laid up ashore that very cold winter, 2 years ago IIRC, or was it 3.
 
Fitzroy said:
I think it did, but the valve doesn't 'know' whether it's ashore or not, does it? Wouldn't this be relying on the water being a few degrees warmer?

If ashore, what if a small crack developed which was just enough to allow a small but constant leak when put back into the water? Or a sudden total failure later in the year?
Click to expand...

Plant a tree in your garden& sit under it in the shade, it will be quite safe until a branch falls. PS a hard hat might be handy
 
When the seacocks fail due to freezing, won't the coffer dams fail due to freezing shortly afterwards?
But the boat won't sink until the ice surrounding it melts....
 
As most of the rest say not sure if its worth the bother, loss of space etc.
But I do have a friend who worked at a council run marina (fresh water) and one bad winter went around in the marina launch making sure everyone's seacocks were shut only to return the following day to find his launch mostly submerged, due of course to a burst inlet hose on an open seacock :o
 
You must log in or register to reply here.

Share this page

Top