Sheer clamps in place

Progress has been slow the last few weeks. Between getting busy with other stuff, and a nasty case of the flu, the boat has been neglected.

But there is progress to report!

Since our last installment, the hull has been turned over. That's a biggie. Its amazingly light. The teenager next door and I got it done with no problems at all. I built a little stand to hold it. Rolled it over, leveled it off, and here we are.

That's actually the last picture for today's entry, showing the location of the sheer clamps, now fully installed.

Getting those on has been a real trick. I found it very intimidating. This is one area where I really don't like the Barlow plans. What I would prefer would be for Barlow to give us a set of exact offsets (from the chine logs), at measured intervals, to establish the location of the sheer clamps. Instead, there is nothing like that. And this is a critical area. Once the sheer clamps are in position, then for all practical purposes the shape of the boat is set. This step matters.

There is an offset provided from the OUTSIDE of the hull at the bow (which is useful), and an offset provided from the top (as the boat sits when right side up) of the planking at the stern (which is useless, since the exact width and position of that plank is not reliable), but that is it. Other than that, there is an enormous amount of rather vague and hard to follow discussion of various techniques and approaches...all of which could be easily replaced by a simple series of offset points.

Alas.

Having read and re-read the plans, I decided I was pretty much on my own, so I set to it. As I see it, there are two big things that you have to get right when establishing the location of the sheer clamps:

• Make sure the front deck will lay properly
• Make sure the boat is symmetrical

That's it. Everything derives from that.

I started by making triply sure that the hull was level, port to starboard. I decided that measuring off the existing hull build was not how I wanted to go, since any minor error so far would just get propagated. Instead, I made my little bullet level my best friend. Everything would be built to level.

First step was to get the sheer clamps dry-fit into position. This meant cutting the ends off at peculiar angles, and trying to get the lengths just right. That was a real trick right there. Lots and lots of test fits and trimming and testing and trimming. Eventually, I got them "close", but the angle cuts never seemed to line up exactly right. No worries. Even though the plans talk about having a tight joint, a butt-joint like that (where the sheer clamps butt up against the transoms) isn't going to give the boat any strength anyway. I don't think it matters if you end up with a 1/8" gap.

Next, I tackled the bow end. I started by cutting a series of straight sticks that I could line up from port to starboard, resting on each sheer clamp.

The plans (in typically obtuse fashion) describe the location of these sticks in two different ways and in two different places. Ignore the plans here.

What matters is this: The overall length of the front deck (measured from the tip of the bow to the front of the cockpit) is created by a single sheet of 4x8 plywood. Therefore it has to end up a smidge under 4 feet long. Allowing for some "room for error", I measured back 3' 9" from the inside face of the bow transom. That was the location of the farthest stick.

I put another stick right up against the transom. That one was easy. 

I then cut two more in the middle, each of those 1' 6" forward (toward the bow) from the one before it. You end up with four sticks spanning thwartship, like the above picture shows.

Next, start with the bow. The plans give you the offset from the outside corner of the hull (where the bottom meets the side and the transom), and you measure up from there. Drill a hole through the side. That's where the top of the sheer clamp goes. I then used my level on the first stick (the one up against the transom) to make sure the stick was level, therefore making sure that the sheer clamps matched, port to starboard.

From there, it was a very tedious process of getting all four sticks level, and making sure that a fifth stick, laid lengthwise across them, made contact with them all. The plans talk about having a 1/4" offset on the middle sticks, but they never explained why, and honestly that made no sense to me. So I ignored it. If they end up off a little as a result, I'll deal with that later.

As you get the sheer clamps positioned at each of the various points, use a clamp and crank it down HARD so as to freeze the position. Its just a matter of lots of trial and error.

The position of the sheer clamps along the rest of the boat is less fiddly. For that, I just cut two more sticks, and made them level. One pretty much right in the middle, one about a foot away from the stern:

And that was that. The sheer clamp position is now established.

Next step is to take a sharpie and mark along the inside of the hull on the top of the sheer clamps the whole length. Then you pull them off and glue and screw them into final position.

I mixed a double-batch of epoxy, and used slow hardener just to be careful (and I have more "slow" than "fast" at this point, so I use it where I can). I thickened it to somewhere between honey and peanut butter, and then slathered a nice thick coat on the sheer clamp (one at a time, of course).

For the glue and screw operation, I found that what worked best was to start with the bow. Position the end of the sheer clamp in position (the rest of it will be laying over the side of the boat...don't even try to bend it into position yet) and then use your third hand to clamp it into place. No need to get it really tight, just make sure you are on the line. Then drill/countersink and screw in a screw as near to the end of the sheer clamp as you can (toward the bow). Now you are locked in, and it gets easier. 

Work your way to stern, about a foot at a time. Bend the sheer clamp into place, align it with the line, clamp it down, drill and screw. 

Once you are about three feet along, you can spring the sheer clamp inside the boat (ie, bring the stern end to the inside of the boat). Use a little spring clamp to hold that end.

Then go back toward the bow, and keep working your way down, a foot or two at a time. I was actually a bit surprised at how easily that went on.

Last step of the day was to scrape off all the squeeze out on the bottom side of the clamp. The top side doesn't matter...its getting trimmed off and sanded flush anyway.

With that, we conclude a long weekend!