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Laker 14 Tunnel Boat Plans
Page Four
Sponson Stringers

Most of the boat is straight and (relatively) stiff at this point. The exception is the sponson tips. These temporary braces take care of that.

But that's not enough. A brace between sponson tips holds them vertical.

Both of these sponson tip braces should stay in place until after the sponson pads and lower sides are intalled.

The sponson keels, where the sponson pads meet the tunnel sides, are simply glued to the edge of the tunnel side.

The lumber I have for this project is 8 feet and 10 feet long, and for most of the longitudinals has to be scarfed to make the lengths needed.

For this stringer, however, I simple butted them together, and then I added this block to secure the joint.

If you haven't done it already, it's time to install the outer bulkhead sections. Again, align the reference line on the bulkhead with the reference line on the tunnel side.

Adding glue blocks to the bulkheads for the chine and the sheer clamp.

The blocks at stations three and two and at the sponson tip need to be angled to properly mate to these stringers. Bend a batten around the structure at these locations to determine these angles.

The aft-most part of the sponson pads should be as flat as possible, and the installation of the sponson battens is a good time to start thinking about this.

With the battens nestled in their notches, lay a level or other straigh edge on top of them and look for high and low spots. Adjust the notches in your bulkheads as needed -- file down those not quite deep enough; shim those too deep.

You're not looking for perfection at this point. There will be a second chance to make adjustments after the battens are glued in place.

To avoid cutting up the sponson tip bulkhead too much, I only carried one of the battens all the way forward. The block underneath the middle batten (as seen in this upside down boat) is glued to all three battens.

The chine log is heavier and stiffer than the stringers installed so far, and has to be bent in two planes and twisted as well.

A complete dry assembly, so that you know exactly how it best goes into place and how it his best held in place, is crucial to success of this operation.

Although a bit narrower, the shear clamp is more difficult to get into place. But don't let the block-and-tackle in the photo scare you. I needed it more as a third hand than for any raw bending power. A human assistant would have been much better.

The shear clamp needs to be tapered to fit snuggly against the chine.

Screw the shear clamp into the glue blocks, but also edge-screw it to the chine log. I also added more glue blocks, and didn't touch the thing for about two days, allowing it all to cure completely before trimming the ends or otherwise putting any stress on it.

Furthermore, I put a plywood cap over the end, just to secure it a little bit more.

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