Whether to repair cracks in clinker hulls

[kestrelleda]

Hi,


Leda is mahogany on oak. The hull is very sound with no rot and she doesn't take in much water, apart from a small leak from the keel box (no surprise) but I've noticed a few cracks along the lines of the fastenings. There are only three or four, they are not very long (a few inches) and they seem to have been there for some time as there is old paint and antifouling in them. Apart from one I noticed last year which was obviously due to some old impact damage, I think they only showed up this year because I cleaned the hull off more thoroughly and washed out the antifouling that was filling them.

Question is, since the cracks aren't apparently causing any problems, can/should I just leave them alone? Or if not, what?

Grateful for any advice.

 

[Peterduck]

If the crack doesn't finish at a rivet, I would recommend drilling a small hole at each end of the crack to prevent it going any further. This can be dowelled or plugged. This is the minimum that should be done. As for doing more, it will depend on how long the crack is, how many fastenings it runs through, etc. Other possibilities include creating a reservoir with masking or duct tape under the crack, and running Everdure or a similar liquid epoxy into the crack. Everdure will get right in there, and probably leak out from the land of the plank below. A follow-up with some more viscous epoxy should complete the repair.
Peter.

 

[trouville]

Not epoxy its to hard and cracks away from the wood especialy as the wood there is damp (not bone dry!) Epoxy on a wooden boat is about useless!

Better use aerodux but in this case leave and look, if its just one fastening and the crack isent more tha 2 inches.then ok i have several like that and even a crack between fastenings !!

Glueing wont strengthen and could even make it worse! if it leaks then just wait for it to take up if not put some mastic on the outside.if your in the water then rub some putty into the crack and leave some pressed on that will fill a fine crack.

Clinkers very strong far more so than cavel

 

[skipperscouse]

If you're not planning on going too far offshore and you're sensible , then I'd just fill the cracks up with raw linseed oil . The wood loves it . If the cracks are very fine then thin down with parafin. And keep an eye on things.

Pete

 

[kestrelleda]

Thank you all for your advice. I haven't had previous experience of clinker hulls so I'm not at all sure how common or serious this kind of fault is. I'm beginning to get a feel for what to do now.

THe boat is out of the water so I'll have a good look tomorrow and see exactly how far these cracks extend. I should be able to see if there is any indication of the cracks being 'live' - any areas not coated with old paint would suggest that.

I have to say I don't like the idea of using epoxy. I didn't find it effective on my previous boat, which was carvel mahogany. I suspect that if it did stick well it would create a hard spot that could actually make matters worse, creating stresses in adjacent areas, or force the cracks wider as the wood swells around it once in the water.

Presumably, if repairs were needed, it would mean scarfing in new sections? Not a job I'd be qualified to do, and not cheap to have done, I'd guess.

 

[ccscott49]

Dont need to scarf in new sections, just drill the ends of the cracks and dowell, use any waterproof glue you are happy with, this will stop the cracks progressing. Just keep a weather eye on them. If you do need to repair, then put splines in the cracks..

 

[philhopson]

Depending upon the size location and severity of the cracks, there is another method you could use. Drill holes at each end of the crack, plane down a thin piece of wood to fit the hole (and I mean really, really small - so it slots in with lots of room to spare) - then use something called "life caulk" which is a flexiable waterproof caulking solution - covering the thin strip with this - and the hole its going into- this still leaves the plank with the flexibility, but cures the hole!

Just a thought - hope it helps!

Phil

 

[kestrelleda]

Thanks again to all for the advice. I thought I should let you all know what i decided after a closer inspection.

At the boatyard I was lucky enough to meet a local boatbuilder who was familiar with clinker and had worked on Kestrels and we had a close look at the boat together. The decision was to leave well alone for now, keep an eye on things and if any problems develop do a proper repair with new plank sections.

It seems best to leave it for now as the cracks, though quite long, have obviously been there some time, end on rivets, and are not causing any leakage.

We thought regluing or splining would not work for several reasons. The planks affected are right underneath the hull, which is quite flat on a Kestrel, and so they're difficult to work on. The timber there will be of course still be damp even after some time on land. There is very little wood to reglue on the edge side of the cracks - little more than a splinter. With the plank on a bench and dried out, it could be reglued effectively, but any repair in situ would probably not be worth the trouble. The glue line, on damp timber, right along the rivets, almost certainly woulnd't hold. There's no actual gap to squeeze glue into so the split would have to be opened out and that would leave almost nothing left to glue back. It wouldn't even be possible to squeeze any useful quantity of mastic or putty in.

The suggestion for a proper repair was to remove the damaged sections, use them as templates to make new ones and butt-joint them in with butt blocks behind the joints. It's not a job I feel very entusiastic about, but if needs must...

 

[fisherman]

Don't get in a panic if you have to repair, which seems not to be the case. I shot in two lengths about 5ft on the turn of the bilge, piece of pastry in clinker.