Cauking a thoroughly dried-out hull.

by Ken McKelvie
(Lincolnshire, UK)

Good day boaters,

I have recently taken on a 13ton Hillyard ketch which has been left ashore in Spain for 7 years and so is completely dried out.

Apart from some major cracks between the coachroof windows, and the partly rotten
keel(!!), the major problem is that the plank seams have opened up.

Daylight can be seen through the sides and bottom of the boat from the inside.

The larger gaps are around 25mm / 1/4 inch.

Is it possible to caulk gaps of this width or will the hull need to be splined, which may then cause problems when the boat is put back into the water?

If it is possible to caulk these seams, how do you prevent the caulking cotton from falling in to the inside of the boat??

Any suggestions will be gratefully received!

Thank you,

K.J.McKelvie, Lincs



Comments for Cauking a thoroughly dried-out hull.

Click here to add your own comments

Thanks Tord
by: Ken

Thanks for your comment Tord.

I know exactly what you mean about avoiding spoiling a wooden hull. The sheathing (if that's the correct term?) would only be done as a last resort and in order to save the boat. I'm thinking that sheathing means coating with fiberglass, we would have the hull epoxy coated, or is that the same thing??

The hessian on the inside certainly sounds worth a try although the only sacking material I've seen in Spain has been plastic. I'll see what I can find on my next visit in September.

Wide Seams
by: Tord

Oh, sheathing a carvel planked boat!!!
It’s not something I would recommend.
I’d go with Mike’s suggestions but use loads of ‘Slick Seam’ or something similar, behind those interior slats.

You could try laying some sacking in the bilges, in contact with the planks and keeping that damp, so that the moisture can leach into the planks, oh and sprinkle it with salt.

Thanks Mike
by: Ken McKelvie

Thanks for taking the time to comment on my problem Mike.

Yes, the boat is still on the hard in Spain. It would be quite difficult to spray her where she is now, and as the contents are still in more or less live-aboard quantity, they'd probably get soaked in the process.

We've been trying, without success, to find some secure storage space so the dousing down isn't really an option.

Since posting the query, I've spoken to an Essex boat builder who says that although the hull sheathing option is a last resort, because the hull is so dry, it would be a perfect candidate.

As you say though, first the keel has to be fixed....lots and lots of opportunities for inflated bills!!!

Any more ideas will be received with thanks!

Caulking old wide seams.
by: Mike

Hi Ken,

I'm assuming that she is still in Spain on the hard.

In which case the wood will be very dry and will have shrunk quite a lot.

If it is feasible, give her a good soaking before you start caulking, if she is mahogany planked it will take weeks or even months for the planks to swell by much.

But it is surprising how much that wood will expand when soaked.

Otherwise, when you begin caulking, start with all the tight seams (if there are any) leaving the wider ones until last.

As you caulk each tight seam, that will push the planks either side every so slightly apart.

The accumulation of those very slight shifts might just be enough to have closed up the wider ones by the time you get to them.

Where they haven't closed up enough or where there are wide spots, you could tack a thin wooden slat to cover the inside of the seam.

Only tack it to one plank, but covering the seam and overlapping the next plank, so that it can move as the wood takes up, that should be enough to keep the caulking from falling through.

If that fails then you might have to resort to gluing in some splines.

Remember that it is best to under caulk than to over caulk, even if it does mean having a few leaks.

And if she is mahogany planked, it will most likely take a month or more for her to take up completely once she is back in the water.

But you've got the keel to sort out first, and check all the frames and fastenings etc before caulking.

So if you can, try to keep her as damp as possible while you are doing those other jobs.


Click here to add your own comments

Return to Your Comments.


If you wish to add more photos (or videos) to your post or if you have any problems loading photos use the link below (there is no need to resize or adjust your photos).

All photographs posted here go into the same central receiving account.

I do occasionally receive stray photos.

So, before selecting your photo please use the 'Message Box' to indicate to which post the photos belong.

Click Here to securely send your photos,



I am perfectly aware that the majority of Wooden Boat aficionados are sensible folk.
However, I need to point out that I am an amateur wooden boat enthusiast simply writing in order to try to help other amateur wooden boat enthusiasts.
And while I take every care to ensure that the information in DIY Wood Boat.com is correct, anyone acting on the information on this website does so at their own risk.