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EZ Tunnel Race Boat Plans
Page Two
Sponson Bulkheads & Tunnel Sides

See plans sheet "Basic Structure -- Transverse"

Bulkheads for the EZ Tunnel consist of three separate pieces for each side of the boat, at each station: two "deck bulkheads" above the tunnel plank, and one "sponson bulkhead" below.

Now is the time to cut the sponson bulkheads (and the transom).

Draw and cut out the bulkhead section, then cut out the notches. Notches are 1"x1", more than enough to make room for the glue blocks attached to the adjacent tunnel side or hull side. The extra space will allow water in the sponsons to drain towards the transom.

Next saw out the "lightening" cut-outs, leaving at least 1.5" around the edges. You may find it easier to cut holes with a hole saw in pieces. (The deck bulkheads at station four are too small for any cut-outs at all.) These cut-outs further lighten the boat and ensure good air circulation throughout the hull.

Attach glue blocks to the sides corresponding to the tunnel plank, tunnel side and hull side. The fourth side, corresponding to the sponson pad, will get glue blocks later.

The sponson bulkheads with their lightening holes and most of their glue blocks.

Locate bulkhead number one forward of its station line.

Locate bulkheads two through four aft of their station lines.

I strongly urge that you temporarily intall all the bulkheads and tunnel sides with screws or clamps to make sure everything fits together properly. Then disassemble, and then reassemble permanently with glue.

Preparing to lay out and cut the tunnel sides: see also Preface -- Drawing Curves.

I added these scrap pieces to a full sheet of plywood, using glue blocks six inches wide. The glue blocks go on the back (lower quality) side of the sheet.

You will want to make sure the glue blocks are NOT located at a bulkhead, a mistake that I made. It was not difficult to deal with, but it's worth avoiding.

Make note that the edge opposite the curve is perfectly straight for the entire length of the tunnel side.

The tunnel sides are laid out using the measurements supplied in the plans. Battens are bent through the located points and the curve drawn. Again, see Preface -- Drawing Curves.

The tunnel sides cut out, ready to have the glue blocks added.

When adding glue blocks to the tunnel sides, leave spaces where the sides are joined to the bulkheads.

Using clamps and screws to glue on the bulkheads and tunnel sides.

The tunnel sides can be clamped over their entire length -- if you have enough clamps. Otherwise, you will want to screw them on from underneath.

Carefully clamp the "tail" of the tunnel sides to the tunnel plank, maintaining a 90 degree angle. This area will later be made stronger by the additon of the tunnel spray rails.

Bulkheads and tunnel sides installed.

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