How do I make nice looking topside seams?

[David McCollum]

My existing seam compound has had it. It is falling out all over the place. It is a dark colored, hard, brittle material that is easy to reef out.

What I bought to replace it is Interlux white seam compound for above the waterline. The instructions sound simple enough, but the first seam I did doesn't look very good. The problem seems to be it is very visible, and I thought the ideal look was a seam that is practically invisible.

Do I just apply it with a putty knife, as the instructions say, and strike it off like a mortar joint? or should I expect to sand it smooth after it dries? That first seam I did never dried hard, so it never got to what I would think is a sandable state.

[redbopeep]

It eventually skims over and then slowly firms up, but, as you noted, it doesn't get "sandable" hard anytime soon. We just put it on/in with a putty knife and then used a finger to smooth it over with a slightly concave shape.

If you want a "smooth" finish w/o showing the seams, I think you may have to fair over the seams with a fairing compound of some sort--hopefully someone on the forum will help you with more info!

Best of luck to you

[jimmy]

Getting them perfectly flush is hard. I eventually decided I liked the look of slightly hollow seams. I was using red lead putty, but interlux is probably similar. The last technique I tried before deciding on hollow seams was to fill them slightly over full then go back with a very sharp knife or razor and take off the extra. This worked better than a putty knife which would pull on the seam compound.

[Bob Cleek]

Apply seam compound with a putty knife fair to the surface. It will shrink slightly after a few days of drying. Then apply Interlux fairing compound. Sand flush. Prime and paint. Depending on the shrinking of the planks, you may expect that upon launch there may be some slight swelling that will make the seams stand pround. Some minor cracking as planks come and go is normal. Just the nature of the beast. Nothing you can do about it except sand and apply fairing ("glazing") compound again at the next haul out. It's just the nature of the beast. You won't have "invisible" seams all the time unless your boat is planked with very stable wood, such as teak.

[Peter Malcolm Jardine]

IF your topsides are very stable, you can spline them. Otherwise, what Bob said

[thebrushand]

Apply seam compound with a putty knife fair to the surface. It will shrink slightly after a few days of drying. Then apply Interlux fairing compound. Sand flush. Prime and paint.

Is this technique purely aesthetic or is there some sort of improved longevity for your boat with a "seamless" topside?

[redbopeep]

Is this technique purely aesthetic or is there some sort of improved longevity for your boat with a "seamless" topside?

I was wondering the same thing. If using the interlux glazing compound over the seam compound would lengthen the life of the seam compound, I'd think it was worth doing. Else, I guess its just to make your wood boat look like a plastic boat, eh?