Best caulking product for sealing wood boats

Good evening

What is the best product on the market for caulking seams on a wooden boat.



Caulking Products
by: Mike

Hi Maureen,

I’m not sure about there being a ‘best product’.

It does depend on what you are caulking.

Is your boat a new build a restoration or are you just intending to patch up a leaky seam?

What type of construction is she, carvel, clinker or other?

And by product do you mean the ‘stopping compound’ or the caulking fibers, e.g. cotton/oakum or both?

With a traditional wooden boat restoration it is usually best to restore and maintain them with traditional products.

There are modern marine sealants that can be used in place of the traditional compounds, however, they do come with lots of caveats about moisture levels and the timber being oil free etc.

And some modern compounds are for use below the waterline only others for use above waterline only.

My own preference, for restoration, is to use old fashioned, cheap linseed oil putty mixed with red lead powder, unfortunately the red lead powder is becoming virtually impossible to get hold of.

‘Pettit’ do seam compounds and seam cement, which are oil based and thus better for restoring old boats, where it is virtually impossible to achieve the moisture and oil free levels required by silicon.

For most traditional ‘leisure’ craft with fine seams, cotton (wicking) is the preferred caulking fiber, though oakum can be used on wide seams.

And deck seams are something else again.

If you can tell us a bit more about your boat we might be able to be more specific.

Comments for Best caulking product for sealing wood boats

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by: Mike

On the product specifications it says "Do not use joints immersed in water or applications requiring continuous water immersion".

Best Caulking
by: will

Just wondering if you have ever heard of people using quad Max caulking over cotton caulking under the waterline

by: Mike

Yea, 2 X for cotton, not quite so much for the oakum, should be OK.

Course it depends on the width of the seams, on an old boat these can vary.

Why don’t you work out roughly what you think you’ll need for one side and order it?

Caulk a side, then you will be able to judge whatever you need to finish off the other side.

While you are waiting for the second order you can get on with stopping the first side’s seams with caulking compound.

estimating cotton/oakum
by: John

cotton vs oakum.
Just reefed all the seams on my 6/4 1949 trawler, a monumental job to say the least.

Cotton with oakum pounded over in all seams below and above the wl, wide or narrow.

Any particular reason for using both instead of cotton only?

Can I assume I'll need approx 2 ft cotton for each running foot X2 (oakum over cotton) for each lineal foot of seam,or is there a better way to estimate the amount needed..

Don't want too too much left over.

by: Anonymous

Pettit Seam Cement

Best Caulking?
by: Maureen

Good morning :)

The boat that we are working on is a 1965 Monk McQueen and it is a restoration.

There is presently cotton in the seams and would like to know what caulking compound you would suggest for below the water line.


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