Sheer Clamps and Deck Beams

After much discussion and deliberation, I decided on a technique for fabricating and installing the sheer clamps.  The discussion and deliberation is truly a global issue, having involved my comrade in arms, Andrew (Melbourne) and me on and off for months now.  The questions about how the clamps should be done results from two (or perhaps three) different and apparently contradictory approaches presented in the Oughtred plans.  

Deferring to Occum's Razor, I opted for the simple, direct approach.  I cut the frame tops off 2 inches below the sheer, with the cut perpendicular to the face of the sheer strake and parallel to its top.  I glued three 3/8 inch by 2 inch strips atop the cut frames, thereby enhancing and strengthening the epoxy bond between the frames, the hull, and the sheer clamps.  I used ash, as I have for most structural components in the hull, and applied the strips (laminates) one at a time to the hull.

Third layer of ash laminated on to sheer

Where I needed to join strips for length, I used a simple 45 degree miter cut, butting the edges.  Since I was careful to stagger the mitered joints, and used pretty long (14 to 16 foot) strips, I think this gives a strong enough sheer clamp, and was an awful lot easier to do than scarph joints would have been.

During the sheer clamp fabrication, I learned once again that a boat builder can never have too many clamps.  Because I needed to locate clamps about 2 per foot I needed nearly every clamp I have to do a single strip the full length of one side.  Hence, with 2 sides, and 3 laminations per side, it took me 6 days to complete the sheer clamp fabrication.  I guess I could have applied more than one lamination at a time, but that sort of job always makes me wish I had been born with 8 or 10 arms and hands, so I opted for the slower approach.

Many, many clamps but never enough

Having completed the sheer clamps, I have moved on to making beams for the aft deck and the fore deck.  I guess I could have gone in several directions at this point.  Jim and Dick Wagner, in their 1996 Woodenboat article on building a Grey Seal, seem to have done the cabin bulkhead at station 6 before doing deck beams, but I just felt like doing the deck beams first, and after all, it's my project.  To save bending into small spaces, however, I did complete the final filleting and epoxy coating beforehand in the areas over which I planned to construct deck beams.

I started with the aft deck, once again for no particular reason, except that it was shorter, hence I assumed easier, and I couldn't see any reason not to start there.  The deck beam construction process was somewhat complicated by the fact that Mr. Oughtred doesn't provide beam radii, and, among the three beams under the aft deck (stations 8, 8 1/2, and 9) I could only find a construction drawing for station 8 from which to loft and make a pattern.  Unfortunately, the radii of the three beams are not the same.  I decided to go ahead and fabricate the beam at station 8 and put it into position.  Then I used a batten along the centerline from the station 8 beam to the stern to give me the correct centerline heights for the other two.  With that information, I could construct a pattern for each. That worked pretty well. The beams, by the way, are all constructed of Douglas fir, epoxy coated, of course.

Aft deck beams in place and glued, with kingplank mortised in

The last step was installing the kingplank, which is mortised into each beam, as well as the inner stern. The kingplank is ash. Once glued, the assembly is absolutely rigid and very strong.  All that's left is the deck and bulkhead, and that section of the boat is finished!


Now it is on to the forward deck beams.