Water take up

[Beattie]

After four years out of the water our clinker built boat is back in the water and as may be expected - leaking like a seive. Fortunately she is now holding her own - with the help of a bilge pump - no more night time bailing and hand pumping for us!

The question is - how long do we leave her to take up before deciding it is time to fill in the gaps with mastic?

Another interesting thing we noticed - after being filled up with fresh water a few times the gaps started to close quite quikly but now that she is back in sea water the whole process has slowed down and in some places the gaps have returned to their original size! Anyone know of any reason for this? Before her four years out of the water she was sailing in fresh water - has this had some kind of effect on the take up rate?

Any information or thoughts on either of these or anything about taking up will be very happily recieved

 

[Kristal]

That's interesting... for a while I was convinced Crystal took on more fresh water than she ever took on salt, but decided I must have been imagining it. She is carvel built, though, so either way I can't help you much...

/<

 

[Peterduck]

If you are still getting leaks after the boat has taken up all the swelling that it is going to, you should look at the fastenings. Clinker boats are usually rivetted, so this means getting a hammer and rivetting dollies, and setting the roves down upon the rivets again, followed by re-peening the end of the rivet over the rove. Before you do this, however, take the opportunity to check that some previous owner has not tried to stuff some sort of packing between the lands of the planks. I have found that the fine needle-like tools sold at motor spare parts shops for pulling O-rings out of their grooves are ideal for cleaning out between planks on either clinker or carvel hulls. A clinker hull should not be filled with mastic of any kind. Obviously this does not apply to the more modern glued-lap-plywood clinker boats.
Peter.

 

[ghilliedhu]

I have a small clinker yacht. Most years she takes up in a few hours but I have never left her out of the water more than 4 months or so. I have found that she will still take on a bit of water untill we have had a good sail. Perhaps the inevitable slight movement in the hull helps her finally take up?
david

 

[delamaree]

If she hasn't taken up in 2 - 3 days then you should suspect a caulking failure brought on through either paint/antifoul or the like preventing the capilliary action of the caulking and stopping it swelling to create a water tight seal. Most often the application of sealants like sikaflex in the joints also prevent the take up of water into the caulking and the boat continues to leak like a seive long after it was "re-caulked" with sika. The expansion of the wet timber breaks the waterproof seal of the sika and you become a submarine owner instead of a boat owner.

Rarely would the rivetting require a refix if the boat was largely watertight initially. As for the fresh vs salt issue, I can only assume the fresh water is rain water whilst the boat is on the hard and entering the interior of the boat, whilst the salt must penetrate the timber from the outside through well brined and pickled timber.

Salt water will shrink the connective membranes in timber yet allow the stringy bits (think celery stalks here) to elongate. It is the elongated strings that give the timber its durability, flexibility and strength when pickled. The denser the wood, the more stringy bits there are and the less cellulose padding around it - hence good hardwoods are much better boat timbers than softwoods with a couple of exceptions - celery top and norfolk island pines.

Hope this kinda helps.