Seam caulking question

[jerrytug]

When they used to, or still do, caulk hull seams with warm pitch, how did they get it to enter the seams, against the force of gravity, doing the underneath of the hull?
Decks no problem obviously, pour it in then scrape it off later when set.
Am I missing something or is it impossible to make hot pitch flow upwards? cheers Jerry.

 

[pmagowan]

When they used to, or still do, caulk hull seams with warm pitch, how did they get it to enter the seams, against the force of gravity, doing the underneath of the hull?
Decks no problem obviously, pour it in then scrape it off later when set.
Am I missing something or is it impossible to make hot pitch flow upwards? cheers Jerry.

My impression is that you don't need too much pitch. The seam is caulked with a fibre such as cotton or oakum which fills most of the seam. The pitch is then absorbed by this fibre when it is brushed in.

 

[NormanS]

We used hot pitch for paying deck seams, but stuff called "Black Putty" for the hull. It is a brown fibrous bitumastic? putty, and was just pressed in with a putty knife. I think some people used pitch for hull seams, and it was put in with a screwing action, using a small brush. For small jobs Aquatex, a bltumastic roof repair putty is sometimes used. All this is of course after caulking.

 

[jerrytug]

That's very interesting thanks. I am hoping to buy a larch on oak gaff cutter ('giving it all up for timber'!) and although I'm handy at sailing them, I have never owned a wooden boat bigger than dinghy size..probly more obvious questions will be appearing soon..cheers Jerry

 

[Capt Popeye]

MMM, if the pitch was being used to caulk the seams, then, in my experience, the hull underwater was also coated with the pitch, as an antifoul and timber preserver.
So painting the hull with pitch, after the seams were caulked /filled with oakum or cotton also painted in the seams between the planking. Allowing of course, the seams to close up after being afloat for awhile. Probably the oakum /cotton could be compressed when the planks took up, and the small amount of pitch be squeezed up without damaging the edges of the planking.
Last thing anyone would want is a hard caulking filler, could damage the planking edges when planks taking up, then fall out when planking dries out for any reason.

 

[NormanS]

MMM, if the pitch was being used to caulk the seams, then, in my experience, the hull underwater was also coated with the pitch, as an antifoul and timber preserver.
So painting the hull with pitch, after the seams were caulked /filled with oakum or cotton also painted in the seams between the planking. Allowing of course, the seams to close up after being afloat for awhile. Probably the oakum /cotton could be compressed when the planks took up, and the small amount of pitch be squeezed up without damaging the edges of the planking.
Last thing anyone would want is a hard caulking filler, could damage the planking edges when planks taking up, then fall out when planking dries out for any reason.

The correct type of pitch never goes completely hard, otherwise when used on deck seams you would have no end of leaks.

 

[Capt Popeye]

The correct type of pitch never goes completely hard, otherwise when used on deck seams you would have no end of leaks.

Ahoy there NormanS, totally agree with you, the pleasure of applying hot pitch to the underside cannot be matched by applying the (any) antifouling of any type. Sticks like .... 2 a ....... smells good and (if stories of tarmacs are to be believed) really does you good. Because the hot pitch stays flexible it also gives with a timber hull that is flexing a bit due to requiring re fastening.

 

[Woodlouse]

The correct type of pitch never goes completely hard, otherwise when used on deck seams you would have no end of leaks.

Pretty sure thats exactly what pitched decks do result in.

For the op, provided one isn't buying a complete dog then it's highly unlikely to have pitched seams in the hull. They should at least be puttied up with red or white lead putty, they might be mastic or even splined. Really pitch is dead for caulking purposes now since there are so many superior alternatives. The only thing it is still good for is pouring in the bilge in places that otherwise would let water stand.

 

[Sniper]

I think what you want is red lead putty. Mix red lead powder with ordinary linseed putty until it is a vibrant orange colour, add a bit of grease as well and then work it in to the seams with a putty knife.

 

[jerrytug]

Pretty sure thats exactly what pitched decks do result in.

For the op, provided one isn't buying a complete dog then it's highly unlikely to have pitched seams in the hull. They should at least be puttied up with red or white lead putty, they might be mastic or even splined. Really pitch is dead for caulking purposes now since there are so many superior alternatives. The only thing it is still good for is pouring in the bilge in places that otherwise would let water stand.

Thanks Woodlouse, for the info. It's the one in Falmouth which Doug748 posted was nice, a few threads below this one. Splined I doubt, must be putty or mastic. A friend spent thousands doing his seams on an aged fishing boat with the very best Sikaflex, 20 yrs ago, still no leaks at all.

 

[upcountry2]

That's very interesting thanks. I am hoping to buy a larch on oak gaff cutter ('giving it all up for timber'!) and although I'm handy at sailing them, I have never owned a wooden boat bigger than dinghy size..probly more obvious questions will be appearing soon..cheers Jerry

What happened about the Saga 40 Jerry?

 

[jerrytug]

What happened about the Saga 40 Jerry?

PM coming

 

[Woodlouse]

Thanks Woodlouse, for the info. It's the one in Falmouth which Doug748 posted was nice, a few threads below this one. Splined I doubt, must be putty or mastic. A friend spent thousands doing his seams on an aged fishing boat with the very best Sikaflex, 20 yrs ago, still no leaks at all.

Ah, very nice. It's hard to tell from the pictures but I'd say she looks too fair to be caulked with any mastics. It'll most likely be red lead putty under the waterline, I'm not going to guess at the topsides without having had a good look at them. It's one hell of a paint job though what ever it's covering!

 

[jerrytug]

It's one hell of a paint job though what ever it's covering!

Yes it's worryingly shiny

 

[BoatShowAvenue]

Thanks Woodlouse, for the info. It's the one in Falmouth which Doug748 posted was nice, a few threads below this one. Splined I doubt, must be putty or mastic. A friend spent thousands doing his seams on an aged fishing boat with the very best Sikaflex, 20 yrs ago, still no leaks at all.

Well, Sika is one of the best poviders out there, it's normal to see those results, if you want results that last in time, you should try it.

 

[jerrytug]

Well, Sika is one of the best poviders out there, it's normal to see those results, if you want results that last in time, you should try it.

Yes indeed, but I wouldn't fancy trying to scrape it off for any maintenance issues..

 

[Woodlouse]

Well, Sika is one of the best poviders out there, it's normal to see those results, if you want results that last in time, you should try it.

I actually already do for my topsides. I suppose the stability of the planks through out the year varies from boat to boat but I find that when caulked with sika or something the seams can show because the planks have swelled and caused the sika to bulge slightly.

 

[jerrytug]

I actually already do for my topsides. I suppose the stability of the planks through out the year varies from boat to boat but I find that when caulked with sika or something the seams can show because the planks have swelled and caused the sika to bulge slightly.

I would tentatively suggest that sika might expand/rebound better, to fill the re-opened gaps,when the planks shrink again, eg during a winter layup? Compared to trad caulking which might stay squashed?

However caulking is part of the structure of the hull because it stops lengthways movement (shear) between adjacent planks, thus protecting the fasteners from being wobbled in their holes, and contributing a lot to the strength of the hull.

It's a complicated subject..I would be interested to know what a top modern builder of trad gaff cutters, eg Luke Powell, has been using in his newbuilds since Eve of St Mawes.

 

[Tranona]

Yes it's worryingly shiny

That is probably because of the construction method. Looking at the photos the hull seems very stable and rigid. The scantlings are massive and the rebuilt deck can only add to the stiffness of the structure. Therefore there is unlikely to be significant movement in the planks so the seams are stable. Doubt very much that pitch has been used in the seams.

If you keep on top of the maintenance requirements that should be a durable boat - after all it has already had nearly 60 years good use and still looks good.

 

[jerrytug]

That is probably because of the construction method. Looking at the photos the hull seems very stable and rigid. The scantlings are massive and the rebuilt deck can only add to the stiffness of the structure. Therefore there is unlikely to be significant movement in the planks so the seams are stable. Doubt very much that pitch has been used in the seams.

If you keep on top of the maintenance requirements that should be a durable boat - after all it has already had nearly 60 years good use and still looks good.

Yes there's a sister in the States which has been round the world and looks like new. I have just been on the phone to the broker, starting negotiations, fingers crossed this might be the one..