I hope everyone had a great holiday, I know I did. I’m sure we all enough rich food and family togetherness to last another 360 days or so. Now back to saving the world of wooden boats a few at a time.
Keeping water out of boats is a strong theme in wooden boat work. On smooth plank boats (known as carvel planked), one of the first lines of defense against water is caulking. Caulking is basically filling the seams between the planking with some sort of natural fiber that swells when wet. I’ve heard of animal hair being used in olden days, and maybe it’s used currently in some lesser developed areas. Now we use mainly cotton, and sometimes a tarred hemp for bigger boats. I’m using cotton to caulk below the waterline in the 12 1/2 daysailer that I’m restoring. The perfect seam in a carvel planked boat has a light tight fit on the inner third of the plank, and a gradual bevel opening up to maybe 1/16″ for every 1/2″ of plank. This perfection rarely happens in the boat shop of course, but ya gotta have goals. Here’s a picture of some tools for caulking.
In the picture, we have three different sized caulking irons, a homemade caulking mallet, and a box of cotton (vintage diaper box optional). It’s an over simplification, but the different sized irons correspond to different sized seams. Caulking used to be a career in itself, and professional caulkers would have dozens of different irons for the various odd seams on a boat, different sized seams, and different stages of the caulking process. Weak minded folks, like myself, that go into wooden boat work nowadays, have to do a little bit of everything, so I just make do with a basic set of caulking tools.
Here’s a picture of the cotton just pushed into a seam:
By making the loops bigger or smaller and changing the spacing of the loops, you can control how much cotton goes in the seam. Bigger seams, more cotton. What you’re looking for in the end is a wad of cotton packed firmly in the middle of the seam. This next picture show that I’ve started pounding in the loops:
Once the cotton is packed into the seam, you can’t really see it, so I did’t take a picture of that. After a seam is caulked, you paint the seam and cotton, which kind of ‘sets’ the cotton. Every boat shop has a can of ‘slop’ paint that has been accumulated over the years that is perfect for this job. You can then putty the seams flush, and cross your fingers that the water stays out.