Seam sealant (which one)

[d4dunmor]

Need to re caulk a 38 ft carvel hull
Larch on oak built fishing boat
What should be used to pay the seams
Sikaflex or the oil based putty that was in her
Seams are mostly tight enough about 3 mm
Getting conflicting information about what to use
Any help out there ?

 

[johnlilley]

If the planking is a bit elderly and likely a bit contaminated with diesel fuel and oil etc. then best to use red lead putty. Get some red lead powder and add some to linseed oil putty. Sikaflex will not adhere to contaminated seams whereas putty will almost certainly perform better.
You can use sikaflex on new planks but why bother mixing systems when putty will be fine. Just make sure the cotton is sound though, as if it has rotted, you are not going to get the advantage of the work you are putting in.

 

[dur]

If the planking is a bit elderly and likely a bit contaminated with diesel fuel and oil etc. then best to use red lead putty. Get some red lead powder and add some to linseed oil putty. Sikaflex will not adhere to contaminated seams whereas putty will almost certainly perform better.
You can use sikaflex on new planks but why bother mixing systems when putty will be fine. Just make sure the cotton is sound though, as if it has rotted, you are not going to get the advantage of the work you are putting in.

... and the grass is hardly ever greener on the other side of the fence so if it worked before why change?

 

[Keith 66]

I was taught always paint over the caulking cotton or oakum with primer or red lead paint, them put the red lead putty in & paint it. Lasts for years.
Its pointless putting modern goop in an old boats seams as it wont stick due to oil contamination.

 

[d4dunmor]

Thanks johnlilley dur and Keith
All seem to say the same message
Thanks for the help and information

 

[Keith 66]

Further to this, if the caulking is sound but the boat is opened up to extent she will leak badly it can be useful to run a bit of Evomastic along the seam or land if its clinker, Its oil based, soft & will squeeze out as she takes up. Cheap as well! saves bucketing for days & keeps the mud out of the bilge.

 

[Paddy Layback]

Further to this, if the caulking is sound but the boat is opened up to extent she will leak badly it can be useful to run a bit of Evomastic along the seam or land if its clinker, Its oil based, soft & will squeeze out as she takes up. Cheap as well! saves bucketing for days & keeps the mud out of the bilge.

Good tip.

 

[itchenseadog]

I agree with John Lilley that red lead putty is best for an old hull but be careful of the red lead powder. As apprentices, we must have mixed tons of red lead powder with our bare hands and wondered why we have since suffered skin problems. Use latex or similar gloves. Our normal practice was to use red lead putty below the waterline but white lead putty on the topsides. We used to mix a small amount of goldsize to the putty so that the oil wouldnt keep leaching through the paintwork.