A Little Bit of Caulking Work

Three types of caulking irons each witha specific purpose

This is a shot from a few weeks ago. I was caulking the completed planking on the starboard quarter. The three different irons each have a unique shape and are designed for a specific job.


The bottom iron is known as a bent iron. It is made this way for just the purposeĀ  you see, caulking a seam up against an obstruction. The second iron up is a making, or caulking iron. It has a fine edge designed to wedge cotton, or oakum into a seam. You can see the cotton has been looped loosely in the seam prior to driving it in completely. This looping allows the caulker to control how much or little cotton goes into the seam, depending on how wide or narrow the seam is. The top iron is a setting iron. Its driving edge is blunt and is designed to drive the full width of cotton into the bottom of the the caulking seam all in a bunch.

A good caulking seam is about half the thickness of the plank and open, in this case, about 3/16″ on the outside. Ideally the planks are touch, wood to wood, for the first half of their thickness. I say ideally, because, well you know, we don’t live in a perfect world now do we.

All Hands to pay seams

This shot is both instructional regarding paying seams after the planking has been caulked and primed and it is a testament to the strength of our staging.

Paying is a boat builder’s term for filling the seams with putty after the caulking. we are using a modern, linseed oil based compound. In the 17th century the seams were often filled with molten pitch applied with a mop. Yum.


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