cap rail bedding and chainplate fibers

Bob L · Post by **Bob L** » Fri Jul 14, 2006 8:48 pm

I'm putting in a section of cap rail. There's white rubbery stuff under the old splinters. When bedding the new section, should I use 5200 or Polysulfide?

Also there is some sort of fibrous material around the chainplates (this is the section I'm replacing, obviously). Leave it alone and caulk over it? Or pack more of the same around it so I can pull the chainplates if needed?

Thanks folks!!!!

Bob

Post by **Tim** » Sat Jul 15, 2006 5:47 am

Polysulfide would be fine for bedding the cap rail--no need for 5200 here.

I can't quite picture what you're describing with the chainplates. Do you have a photo?

Bob L · Post by **Bob L** » Sat Jul 15, 2006 9:53 am

Thanks Tim - but didn't you use 5200 on the toerail of Glissando? I'll get you a picture today. The deck and hull meet to form raised gunwales, and most of this is glassed together - except where the chainplates penetrate. Here there is a space bigger than the chainplate bar (leaving about 1/4" gap) so the chainplate can flex (I guess). The chainplates have a plate around them to seal this area. I believe when the chainplates need to be serviced, they can be unbolted from below, the plate removed, and the chainplate bar extracted. This packing material looks like flax, or the stuff between the boards of a wooden boat (caulking? oakum? flax? - the word escapes me).

Bob L · Post by **Bob L** » Sat Jul 15, 2006 3:01 pm

Pictures of the fibrous material:

space around chainplates for movement (is this enough?):

Dry-fit of caprail:

Post by **Tim** » Sat Jul 15, 2006 5:44 pm

I used 5200 because I was relying on its adhesive qualities to hold on my rail; at only 1/4" thickness, there's not much to hold a screw head from pulling through under strain, so I wanted the adhesive to do the real work, with the screws just holding it till the adhesive cured.

In your case, you should have plenty of beef all around for the screws, so I don't see a need for 5200 there. Since you're just sealing the board in place, I'd chose a polysulfide.

The fibrous material is a mystery to me. I can't identify it from the pictures and am not really sure what purpose it serves. Do you think it might once have been a packing material that squeezed around the chainplate when the top plate was installed, or is it just a filler to fill up the large void around the chainplate and give sealant a place to rest without falling through?

I think what you really want here is lots of good sealant so that you don't get any leaks through the chainplate.

Bob L · Post by **Bob L** » Sat Jul 15, 2006 6:18 pm

>Do you think it might once have been a packing material that squeezed >around the chainplate when the top plate was installed, or is it just a >filler to fill up the large void around the chainplate and give sealant a >place to rest without falling through?

That sounds like a rational explanation. I'll slather it up with polysulfide, and screw it down. How about the gap I left around the chainplates? Big enough to allow for flexing? Fill it up with polysufide?

Thanks again. Now if I can find an easy way to remove old varnish, I'll be set... the boat will be de-teaked, except for the cap rail and whaleboard - and that will be covered with canvas, only to be exposed for special occasions, like the Cubs winning the World Series...