Wooden boatbuilding, Lugged steel bicycle frames, computers. The usual.
Monday 16 June 2014
More centerboard work, plus centerboard case
So here's the centerboard all nicely shaped. I added an uphaul pivot, made with two pieces of jarrah that sandwich the centerboard. It's held together with epoxy plus four 38mm 8G silicon bronze screws, so it should be nice and strong. I routed a nice big 20mm wide slot to accept either a sheave and metalwork for a becket for a 3:1 uphaul, or if it's still hard to haul up, a pair of sheaves for a 4:1 uphaul.
Next I made it look ugly by laying lots of 200 gsm unidirectional carbon fibre on either side. This stuff provides the strength. Not shown here (I forgot to take a photo) is a strip of 400 gsm fibreglass tape down the leading edge and across the tip, with a second piece at the tip of the leading edge.
Then I faired it. I used much the same epoxy mix that I make for gluing, with enough glue powder to make a peanut-butter consistency. I slathered this on with a spatula that I stole from my kitchen, and then after curing I removed most of it with some 60 grit emery in a sander. Then I repeated the exercise, with slightly runnier goop.
Once I was reasonably happy with the shape and surface, I bunged a coat of undercoat on. Once this is dry I'll remove most of it before doing a couple more coats and a couple of top coats. Also shown here is the case, which is framed with 19x42mm Tasmanian oak, and held together with no less than 48 8g silicon bronze woodscrews.
The pivot is only temporary. I've been testing how it works with an M10 bolt. I've got some more bronze on order to make a proper pivot, using a 12mm bolt to clamp a 19mm tube, with some 25mm OD flange pieces epoxied into the centerboard. I'll show details of that once the materials arrive.