View Full Version : spun cotton or wicking for 5/8" plank seams?

06-12-2006, 07:24 PM
For those carvel plank experts: What's the stronger, more leakproof method of caulking... looping/gagging/malleting spun cotton or wheeling cotton strand wicking for 5/8" thick plank seams? I've read a number of good books on the issue and there seems to be no consensus.

I'll add the caveat that I'm just developing the technique for looping/gagging, having just used that method for the garboard seam. Maybe I'm too cautious about this part of my project, but I don't think you can overestimate the importance of a solid caulking job...especially where the beveling in some of my after planks isn't what I'd call perfect.


Any thoughts on the preferred method?


Dan McCosh
06-12-2006, 07:37 PM
I've never had any luck with spun cotton. The twisted strand type has always been easier for me to handle and control. The boat looks great--I trust you mean a seam in 5/8 ins. planking, rather than a 5/8 ins. seam.

06-12-2006, 07:57 PM
Oops...yeah, the planking is 5/8ths thick. Thank God the seams aren't that wide!

Anyway, I know what you mean about the wicking. It goes in a lot easier than driving the spun cotton. I just don't know if it's more effective in the long run.


Peter Malcolm Jardine
06-12-2006, 08:21 PM
Nice boat. :)

Dan McCosh
06-12-2006, 08:31 PM
The effectiveness is mainly the result of it being driven in to the correct hardness, filling the seams while leaving room for seam compound, etc. I don't think there is any particular drawback to using the pre-twisted form, although you don't have infinite flexibility as to how much goes in the seam.

Jay Greer
06-12-2006, 11:58 PM
On a hull planked as thin as you describe, candle wicking that has been rolled into the seams will, most likely, be a better choice than tuck driven cotton. The planking is too thin to withstand much tension from traditional methods of caulking.

06-13-2006, 11:22 AM
As Jay said, 5/8" planking is a bit thin for driving cotton with an iron & mallet, I think about 3/4" is as thin as one would usually go for traditionally caulked seams.

06-13-2006, 08:04 PM
Thanks, guys. I'll go with wicking, and will drive spun cotton into hood ends at stem and transom.


Don Kurylko
06-13-2006, 11:08 PM
Candle wicking is just that, candle wicking? Any particular size or type that is appropriate for 5/8 planking. There is a fellow up here who is about to try caulking a small motor skiff that he is restoring with cotton strand, but if wicking is better Id like to pass that information on to him. I presume its pretty easy to make a caulking wheel too?

06-15-2006, 08:00 PM
As far as I know, cotton "wicking" is probably not the same as candle wicking. Check out Jamestown Distributors. They have 7-strand wicking which works great. If the seam is too small, you simply pull a couple of strands off. The stuff is very inexpensive as well.