seam sealing laps

[Darrell Van Eck]

Thanks to Andreas I can say I have a 62 Seacoaster, Thanks again Andreas!

Hull bottom is completly stripped of paint including in the lap area seams. I am filling voids and screws at this point and wil be done with that very soon.

I will be ready to prime the bottom by the end of the weekend. My question is do I seam seal at each lap seam, or possibly just the seams that are at the bottom, ( below the water line). If so after priming, and before paint, or before priming? Or do I just let the primer & paint fill any possible voids between the lap seams?

Thanks

[JRPfeff]

Darrell,

I didn't do any sealing of my seams, with the exception of one on each side with a bit of a gap. For those I just used some of the caulk I was using for the keel and wiped it in with my finger. It probably was not needed, because my boat does not leak much through any lap seam.

I recall that I caulked before priming and that stuff took forever to dry. You may not be painting this weekend.

Jim

[a j r]

What do you mean by "seam sealing"? Are you talking about a sealer such as Smith's CPES or Pettit Old Salem sealer? Or are you talking about caulking between the laps?

I say YES to sealing ALL the wood in and out of the boat with one of the above sealers.

Andreas

[Darrell Van Eck]

Sorry Andreas, my autobody talk is coming through here.

What I am talking about is using a little boat-life caulk were the laps join together. The only one I see that has any kind of gap to it is the last one on each side where the hull bottom starts. All the other ones seam real tight together.

Thanks

[Rodney Syverson]

I think I would use 3-M 5200 cold weather as this will set up in a few days instead of weeks. It has tremendous adhesion and flexibility. Takes primer and paint fairly well also. Some books suggest a small fillet on all strakes to seal, but for the most part your seal is the joint and sealant between the two strake faces. A fillet on all strakes may not be necessary but certainly would help fill some gaps that might be unsightly. Of course all bare wood should have a couple of coats of CPES before any sealant or primer is placed over the top. Rod S

[gts]

So Andreas, do you have an opinion on the subject of applying a fillet (polysulfide or polyurethane) to the laps to reduce leaks?

Just out of curiosity, what would you think of a fillet of West System epoxy applied to the laps to seal them?

George

[LancerBoy]

West System is a BAD application in this instance. It is way to stiff and brittle. You need something that moves and flexes with the boat such as a flexible marine caulk.

Andreas

[gts]

That was a trick question, Andreas. I had a "professional" wood boat guy looking at the hull and he didn't see any problem with the West System an earlier hack had spread along the lap seams after an attempt with 3M 5200 had just resulted in six foot long caulk strings peeling off the hull.

So leaks in the keelson are easy to find. (Trust me, I keep finding them. Ha ha ha.) How do you find the laps that are a problem? Tilt the hull and spray a little water in there? And once you locate a problem, what's your preferred method for fixing it? If the wood is solid, unbolt a length of that lap, squeeze some Life Caulk between the planks, and re-tighten?

I've got the 20' Thomspon with the cuddy cabin and the hull is mostly in good shape so rolling the hull and replanking would be overkill. And a lot of work.

George

[gts]

So Andreas, what's your preferred method for locating leaks along the lapstrake seams? The keel leeks are easy since just a little water inside the boat shows them - the keel is the lowest part of the bilge. For the laps, do I let it dry out completely and then use the garden hose inside the hull (with the seacock open so not too much water accumulates in the hull) and look for drips on the outside of the hull? Or try to tilt the boat over so the bilge water sloshes outboard and over the lap seams?

I don't need a whole new bottom and the keelson re-sealing went a long way towards slowing the water inflow. But like you say, there's not supposed to be any water in there. From simple (apply a bead of caulk) to difficult (replace the lapstrakes) what are your preferred methods for dealing with lapstrake seam leakage?

1. Carefully chip out the epoxy fillet the last hack applied
2. Clean the seams
3. Make a determination - loose lapstrake means unfasten, clean seam, apply caulk, and re-fasten.
4. CPES along the lap endgrain?
5. Apply a fillet of Boat Life caulk to the seams
6. Paint

George

[john]

I overkill most projects, but my 1960 Cruisers 202 16' has not leaked a drop since redone 5 1/2 years ago, including almost 200 hours of run time, and 8000 miles of trailering.

I dissembled the lapstrakes, stripped and refinished them before assembly, and refashioned with new silicon bronze screws, I used 5200 to glue (caulk) the lapstakes together. Did not replace any lapstrakes, just unbolted and put back in place using same screw holes. Actually very easy after I got over being terrified of destroying the hull.

See www.aerialimaging.net/john for pictures.