Sheer Madness

December 3, 2014  Hours spent building to date:  387

I’m the kind of boatbuilder that sees an open joint not as a problem, but as an opportunity to use more epoxy.  The one thing I’m fussy about is sheers.  On the boats I’ve built from scratch, I have always left them high and shaved them down a lick at a time to where they look right from any angle.

There is a name for it that I can’t remember, but sometimes when you take a perfectly drawn two-dimensional sheer and turn it into a three-dimensional boat, it will appear to have a slight hump up toward the bow.  I once built a half-hull model of a yacht designed by William Fife III, Grand Master of Sheers.  I was able to trace the sheer onto the wood directly from the plans.  No possible mistake or misinterpretation possible.  I laid the finished model on the plans — perfect.  But seen from some angles, it had that little hump.  I had to move it to a side wall of my office, since it was driving me crazy.

So how to deal with the Tardis sheer clamp, upside down and about a foot from the shop floor, with a clamp bigger than the keel of any boat I’d ever built?  I measured and fretted and bent a batten for three or four hours and came to an okay, standing-on-my head sheerline, but couldn’t be sure.  Then I took a very close look at the plan, and realized that the sheer clamp isn’t really the sheer on this boat:

The ACTUAL sheer is the top of the bulwark that forms the anchor well (see plans diagram page).  It comes straight off the cabin sides and is almost flat and will be pretty easy to define once the boat is turned over.  The VISUAL sheer is formed by a) the seam between the well and the hull planking b) a big piece of trim over the seam c) the paint job.  So I will have considerable wiggle-room on the sheer once the boat is right side up.

But then I had to build the sheer clamp.  It has a whole lot of curve in towards the bow, and a whole lot of curve up toward the purposeful, workboat stem that I so admire.  But a conventional lamination wouldn’t take both curves at once.  So it has to be built like a strip-planked boat with many smaller pieces glued together.  3/4 inch thick test strips broke, 3/8’s were too flippy, 1/2-inch seem to work, although I am listening for a crack at almost any time.  3 1/2 wide strips wouldn’t take the upward bend,  1 5/32nd wide would bend, but were so small I would be stripping forever, 1 3/4 seem to work.  That meant cutting 240 feet of strips (24 ten-foot lengths scarfed together into 20-footers).  So by the end of Sheer Clamp Day 3 this week, I have ONE strip on the boat.

It looks okay.  Maybe.  I think.




A football filed of sheer clamp strips.

A football field of sheer clamp strips.

One strip on, 11 to go.  Is that bend a little funk at station 3?

One strip on, 11 to go. Is that bend a little funky at station 3?

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