Frost damage to hull

[BogMonster]

I'd like some opinions/experience on something please...

My Humber has an odd (you might say stupid) "feature" which is that the inside of the hull has a large "wet" compartment, with a bung in each end, one into the anchor stowage space (so you can drain that out I assume) and one into the bilge well at the stern. Not a problem so far ... but the problem is that there is no drain bung at the lowest point of the bilge, only where the trunk is attached which is four or five inches up. So it is not possible to drain the whole thing right out unless using the pump, though when I park it on the steepest part of the slipway I launch from I can get most of it out, at least until the next rain! So when it is left on the trailer with the trunk down, it ends up with four or five inches of water right the way through the boat.

It is presently mid winter here, and while temperatures usually go a degree or so below freezing at night and rise to 3-4 deg during the day, there is a possibility of a period of several days below freezing, and I am going away on holiday for a few weeks....

Should I be worried about the few inches of water inside the hull freezing and cracking the hull? I don't have anywhere to put it under cover nor do I have a boat cover so there is no way of draining it out and keeping it dry. I looked at it yesterday (there has been a bit of snow the last few days) and the water in the bilge was frozen, I think that will be OK because it can expand upwards if it freezes but am now a bit worried about the hull. I'm also not convinced the bungs are a good seal (they don't seem a very tight fit) so the obvious thing of draining it out as much as possible and putting the bungs in, may not work.

Freezing water inside the hull seems like an obvious problem (though the idea of having a drain bung at the lowest point also seems obvious to me!) so am I worrying about nothing? has anybody had problems with this? don't want to come back and find my boat split in two

Thanks

Stephen

[codprawn]

Remember we get a lot more frost in the UK and never heard of a problem. There should be plenty of room for it to expand.

I think I would be more concerned about some damage to the gelcoat allowing the hull to become sodden - then a frost could cause probs!!!

[Erin]

It would have to be more than a couple of days just below freezing for seawater to freeze so I don't think I'd be too worried.

[BogMonster]

Originally Posted by Erin

It would have to be more than a couple of days just below freezing for seawater to freeze so I don't think I'd be too worried.

It is more likely to be freshwater though, from rainfall, as the thing fills up quite quickly when it rains.

Went out for a quick blast today before I go away (3 deg C and occasional sleet squalls, bit of a nip in the air, got to be dedicated to do that, it was efn cold!!!) and after I recovered her I parked on the steepest part of the slipway pumped it all out and sealed both bungs so I hope it will be OK - it just means the anchor space will be full of water when I get back.

The ideal thing would be to drill through the base of the transom and fit a drain bung at the lowest point then could just leave that out when she was out of the water, but I don't feel confident about drilling holes in my boat below the waterline as my fibreglassing skills are non-existent..... the only thing I know about fibreglass is that I remember thinking the resin smelled nice when I was a kid

Oh how I wish I lived in a place where there were skilled people one could get to do such jobs....

[Poly]

if you are really worried throw a couple of buckets of sea water in before you go.

[jyasaki]

Originally Posted by BogMonster

The ideal thing would be to drill through the base of the transom and fit a drain bung at the lowest point then could just leave that out when she was out of the water, but I don't feel confident about drilling holes in my boat below the waterline as my fibreglassing skills are non-existent.....

Do you need to glas it in? How about one of the screw together types that uses rubber washers to seal itself up? All you'd need to do is drill, seal with epoxy or something like 3M 5200, and install the fitting.

In truth, I really don't think you have too much to worry about; if the water did freeze, you're not having it do so in a confined space, so it will expand into the open area above the surface first. It's places like cooling journals and pipes where freeze expansion becomes more of a problem, as it is confined, and has nowhere to expand into.

jky

[Nicksweden]

My mum puts a bundle of straw in the fishpond during the winter months, the theory is that if it freezes the ice crushes the floating straw instead of the sides of the plastic pond................ No idea if it works, but I'm not going to argue with mum!

[Kernow Buoy]

drop a drink bottle in there with an inch of sand in so that if it floats it'll partially submerge, the ice will then crush the bottle rather than putting force onto the hull, outdoor pools do this in winter using large pool chemical drums.

[The Grocer]

Originally Posted by Kernow

drop a drink bottle in there

Hmm.

A bottle in a ship.

Interesting variation on a theme...