For leak repairs, cotton or tube caulk?

[MRFontaine]

I have a 1947 Owens Cutter which I've rebuilt and sailed extensively. She is coated with epoxy and paint and the seams were splined with wood and epoxy. After two hard sailing sessions (20 kts wind, beating) seams are opening around the mast. Sawdust won't close them all, so I'm afraid I need to haul and caulk the leaks. The question is whether I should use cotton or a tube caulk such as 3M5200 fast cure or Life Caulk. Does anyone have experience and recommendations?

[wizbang 13]

I think the clue here is "hard sailing" .
Look at your mast partners/ mast step/ floor timbers / ring frame ... or lack of them .
Sounds like she is being stretched, banging in more cotton may only wedge her open more. Then , frames will start going POW!
Splining does not make a boat stronger, only tighter.

[MRFontaine]

I'm finding out that splining doesn't work. I did it to edge glue the hull on the theory that a monococque structure would be strong and resistant to twist, springing, etc. That hasn't worked as I hoped. So now I'm fixing the leaks as they occur. The mast base structure is sound (a stainless steel cradle with wings that distributes the loads fairly well--I may need to enlarge the wings for more distribution). Right now there is no cotton in the seams. They're all splined and filled with epoxy. So I'm reverting to a flexible caulk regime.

[Peerie Maa]

I'm finding out that splining doesn't work. I did it to edge glue the hull on the theory that a monococque structure would be strong and resistant to twist, springing, etc. That hasn't worked as I hoped. So now I'm fixing the leaks as they occur. The mast base structure is sound (a stainless steel cradle with wings that distributes the loads fairly well--I may need to enlarge the wings for more distribution). Right now there is no cotton in the seams. They're all splined and filled with epoxy. So I'm reverting to a flexible caulk regime.

Did you check the state of the fastenings when you splined her. If as wizbang says there is flexibility in the hull due to inadequate structure, or if the structure is no longer effectively joined together by tired fastenings no caulking, gooy claggum or splines will work. You must find out why she is flexing before you can select a fix.

[MRFontaine]

I refastened and replanked the hull as I rebuilt her and then did the splining and gluing. I suspect that the frames may be somewhat weakened as the boat had been refastened previously by driving in a second set of screws instead of pulling the old and inserting larger diameter ones. That is what I did so I put in about 3200 new bronze screws. In truth, I probably need to have her extensively reframed and replanked, but I'm trying to avoid that idea. The original frames are 1.5 by 1.5 oak, so they can only take so many holes. As an aside, I live in Annapolis, MD about a block from the original Owens yard location and keep the boat at Sarles, the oldest boatyard in Annapolis (1907).

[MRFontaine]

I need to clarify my question. Wooden boats "work." That is, the planks and frames move in relation to each other by a very small amount. Caulking has to allow for that movement while keeping the water out. Cotton caulk has good gap filling properties and elasticity while its adhesive quality is poor. Adhesion is important to keep the caulk in place. Cotton does that by compression. Polysufide, polyurethane, polyether caulks have good adhesive properties and good elasticity, plus they can be dispensed in small quantities. The cracks I'm getting are generally very small: 1/16th inch width, 6 inches long. I need to fill with something that will stay in place, be elastic enough to allow wood movement, yet keep the water out. So will a short length of cotton stay in place , or does it need a long run (feet in length) to provide the overall compression needed to keep it. Conversely, are the poly caulks flexible enough to take the movement without breaking the bond keeping the water out. Bob Adams' reply says using both may be the way to go. Other ideas?

[chas]

Trem-clad Instant Patch, roofing tar with a difference! / Jim

[wizbang 13]

1/16 "x 6"? where?
that does not make sense. That small a crack could just fill with toilet bowl wax.
The working of the compression rig is what is bustin her up.
crack off the backstay and shrouds and stop racing her so hard , at least give that a try.

[Paul G.]

I have a 1947 Owens Cutter which I've rebuilt and sailed extensively. She is coated with epoxy and paint and the seams were splined with wood and epoxy. After two hard sailing sessions (20 kts wind, beating) seams are opening around the mast. Sawdust won't close them all, so I'm afraid I need to haul and caulk the leaks. The question is whether I should use cotton or a tube caulk such as 3M5200 fast cure or Life Caulk. Does anyone have experience and recommendations?

20kts on the wind is not hard work, that's just bread and butter for any half decent yacht. If you have splined the hull fully then you are part way to strip planking, but you need more stiffness. Those small cracks can be fixed with 5200 or whatever flexible adhesive sealant you have on hand. To deal with the deeper problems, make sure you have a decent ring frame around the mast area and the mainsheet traveller/rear cabin bulkhead. But probably the best solution is to wood the hull with a power plane (fast maybe half a day with a skilled guy) epoxy two diagonals of 3/16" veneers at 45 degrees and then glass the whole lot. Not cheap but will give you a solid long lasting boat, replanking and reframing sounds a lot more expensive.

[MRFontaine]

Wizbang13 is right. The floor timbers are loose, particularly under the head compartment (have to remove much innards) to tighten her up. I'm also going to add new floors with long wings to distribute the loads upward. Two things the builders did which made the hull flex (65 years ago) was to use plank on edge floor timbers and not notch the frames into the keelson. Thanks for the ideas on caulks all. Once I stiffen her up, I'll recaulk.

Actually, aside from the leakage around the mast the boat is solid. I've thought of covering her with glass--as that has been done several times (see a Yachtworld ad for a Hinckley-Owens cutter in Florida). But the thought of wooding a 40 foot hull for a second time is not appealing. Besides, I'm not convinced it's necessary if the flexing issue can be resolved. We'll see.