The Sound of Caulking
As you approach the boat these days, you’ll probably hear a kind of rhythmic, chirping, tapping sound. Most likely, that’s the sound of caulkers driving caulking into the seams. Caulkers have a number of specialized tools for their work. The most obvious is the caulking mallet.
The head is made of a very hard wood, and a good mallet will have a distinctive sharp ringing sound when striking the iron.
Next to the mallets picture above are a variety of caulking irons. Although they look like chisels, their edges are in fact shaped to drive the caulking material into the seam rather than to cut it. This is just a small sampling, there are many many sizes and shapes of caulking irons.
There are two layers of material we use for caulking. The inner layer is cotton. This is what Gino is driving in here. If the preview below is not visible, try this link.
Oakum is next driven into the seam on top of the cotton. Oakum is a coarse hemp fiber that’s been treated with pine tar. Evie is driving oakum here. If the preview below is not visible, try this link.
Caulking is only part of what keeps the water out of a boat’s seams. The first layer of defense is a tight wood-to-wood joint along the plank seam. That goes up about 1/3 of the plank width. There is a V-shaped caulking seam in the outer 2/3 of the plank. Into this seam is driven cotton and oakum as you see above. Finally, the outer seam is packed with seam compound, a flexible, sticky substance. In the old days they might use tallow and rosin. Modern boats will likely use a product specifically designed for this purpose such as the ones pictured here. We’ve often used a home-made mixture of roofing tar and portland cement for the larger boats here at the seaport.