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Sport C Tunnel Race Boat Plans
Page Five
Deck Framing

Time to turn over the hull. Take a moment to congratulate yourself for your accomplshments so far. But there's still plenty to do.

Make sure your hull is well supported and free of any twist.

Also, it's time to remove that reinforcement on the beam a Bulkhead #2, and the bracing in the sponson tips.

Installing an outer deck stringer.

The deck stringers at the top edge of the tunnel sides have been installed. The deck battens come next. And then the carlins (where the deck meets the coaming/cockpit).

(I didn't install the carlins until the cockpit was in place, but you will want to install them at this time.)

The deck battens are held flush with the surface of the bow beam, as before. You may need to tuck some small pieces underneath to complete the job.

You will need deck stringers on both inboard and outboard faces of the tunnel sides. The outboard one goes forward to the sponson tip. The inboard plunges downward to the bow beam.

It is not necessary for both stringers to extend the full length of the boat. I have drawn the bulkheads with the assumption the inboard stringer will end between Bulkheads #4 and #5.

Framing the tunnel extensions starts with cross-pieces along the aft ends of the extended tunnel battens. Note that the top face of the piece is beveled.

The gap between these cross-pieces and the middle tunnel battens ensures that water does not get trapped in this area. Drains will be needed in the outboard sides of these tunnel extensions -- more on that below.

One deck batten on each side of the boat extends all the way to the tunnel extension. They rest on the transom beam (I glued a thin wedge underneath) and are notched into the cross-pieces.

Angled blocks are added to the transom beam to bring it up to deck level.

Closing in the tunnel extensions with glue blocks.

The tunnel extension sides are reinforced with a second layer of plywood over the end of the tunnel side.

The inboard faces of the tunnel extensions will be covered by the aft ends of the coamings.

You will need drain holes in the sponsons and the tunnel extensions.

Place the drain holes as close to the lower corner as is reasonable.

Here's how I do it:

For a 3/4" drain plug, drill a 1-inch hole and fill it with epoxy thickened with silica.

Drill a 3/4" hole through the cured epoxy.

Now you have a hole through the hull, but the wood remains sealed from water intrusion.

I have 1.25" drains in my sponsons, but 3/4" would be plenty.

The drains in the tunnel extensions need not be very large at all. Mine are 3/8" diameter.

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