Tuesday, February 13, 2018

Boomkin

A few months back I built up the boomkin spar out of leftover douglas fir that I had from the other spars, but I didn't do a birdsmouth this time. Instead, I ripped four pieces to length about 25mm x 25mm and then cut off a corner of each and glued them up to make a 4 section hollow spar.

Once it had cured, I knocked off the corners to make 8 sides and then rounded the end of it down while leaving the section that will be inside the boat with 8 sides.  I liked building with the birdsmouth method but I just didn't want to take the time for the boomkin since I'm not as worried about weight (although it is still hollow to shave a few grams).

Fast forward to last week and I decided it was time to cut the hole for the boomkin.  Cutting holes in boats always makes me a little squeamish, so I had to come to terms with it on my own time.  To find the location, I basically laid the finished boomkin on top of the stern and eyeballed where it would protrude to the centerline and cut out a 2 inch hole at an angle in the transom, just above the level of the deck.

Next, I cut the same hole in a few pieces of 6mm ply and then rounded the pieces to make a 35mm flange surrounding the hole.  Then I screwed and glued the pieces to the transom and faired it out with some thickened epoxy.  A bit of cleanup with a rasp and sandpaper made it all look good. 

After a test fit, I tapped the inboard end of the boomkin and installed a 5/16" threaded insert and tapped a corresponding hole in one of the frames to anchor the boomkin.  I found a 5/16" thumbwheel and screwed it in place.


I still have to leather the boomkin where it intersects the hull and soak in some Deks to protect it, but aside from installing the mizzen sheet hardware (a turning block, and clam cleat), I'm checking it off my to-do list.