Alternative to conventional caulking?

[DownWest]

This might offend trad boat owners, but here goes...

We have a '56 close seamed mahogany 27ft motor sailer here. It seeps a bit from the planking around the aft engine area and this led to it sinking a couple of weeks ago. She is back up and now needs a solution.
One that came to mind, was running a 2mm panel saw down the offending seams to a depth of 6mm, then coating the gaps with a thin époxy. Shove in a 3mm rubber cord and top off with PU mastic.

The boat was built in Sweden and suffers from the hot summers here, to the extent that the topsides open up enough to see through the gaps. That is not a problem, as she only serves as a river pic-nic boat and will not go to sea again. The rig has not been fitted since she arrived here 12 yrs ago.
The idea of a flexable 'O' ring type joint in the gaps has some appeal.
Any comments?

 

[Keith 66]

I think you are on a hiding to nothing. The wooden boat forum often has threads to do with caulking & modern approaches rarely seem to work. If the boat is close seamed, you could spline it or if the gaps are small roll a strand of cotton in & top of with modern goop. Out of interest what colour is she painted? if its a dark colour she will suffer something awful regardless of what you do. White is a lot kinder for a wooden boat.

 

[DownWest]

I think you are on a hiding to nothing. The wooden boat forum often has threads to do with caulking & modern approaches rarely seem to work. If the boat is close seamed, you could spline it or if the gaps are small roll a strand of cotton in & top of with modern goop. Out of interest what colour is she painted? if its a dark colour she will suffer something awful regardless of what you do. White is a lot kinder for a wooden boat.

Hi Keith
Varnished topsides, antifouled bottom. We are hauling her on Monday and will do it over a couple of days. Splining was considered but this is only below the waterline, and about a 1/3 of the length, plus problems in sourcing wood for the splines and accurate sizing. Tests indicated a 3mm groove and 4mm rubber cord. A waterbased Resoltech resin is the choice for the coating and Sika 11FC as the sealing top off.
I will post what happens when she goes back in.....

 

[RMTB]

I have done something close to this.
After a ten year rebuild on my 70 year old H28 Herreshoff, the original planking had shrunk so much that
I did not think I had the necessary skills to use traditional caulking.
So all the old caulking that had not fallen out was removed, made a jig and routed all the seams to 6mm,
Primed the inside of the seams then caulked the whole hull with a polysulfied adheasive/filler.
After launch the filler bulged out as the planks expanded, this was paired off at anti foul time.
Now eight years later, the bilge pump monitor shows very little activity - other than when we get bounced around for
six to ten hours in a way that only the Bristol Channel can provide, after which the hull settles down and becomes tight again.
Interestingly I do get asked now and then if my hull is fibre glass, which I take as a complement.

 

[DownWest]

.
Interestingly I do get asked now and then if my hull is fibre glass, which I take as a complement.

I get asked if my hull is wood. It is clear finished ply with similar hardwood, no paint. I try to be patient....
That is an interesting effort. It now looks s if we might Dynel the hull below the waterline. The époxy/rubber cord/mastic worked very well, but a slight bump on launching exposed another rot problem in the topsides and it now looks as if a more prolonged rebuild is looming. It has got a bit below the curve that wooden boats need to stay above.