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EZ Tunnel Race Boat Plans
Page Six
The Deck

Short glue block, approximately 1.5 inches long, are added along the of the hull sides from bulkhead two to the bow.

The tunnel extension requires a bit of framing. I treated this area a little differently on the original EZ, so these photos are borrowed from the Pro Tunnel building notes.

Before you install the deck, make sure that there is no way for water to enter the closed space you are going to create here. The most likely area of concern is the cut-out in the coaming for the tunnel plank. Force some thickened epoxy into any gaps that might be trouble.

See your plans for details and options regarding this area.

On piece of hardware should be added at this point -- the bow ring.

I started by adding a "pad" about four inches wide, extending from the breasthook to bulkhead one.

I used a simple, hardware store u-bolt for my bow ring. It is located about eight inches aft of the bow beam. Washers are used under the nuts. Caulk under the washers prevents water from entering the holes drilled though the hull and getting into the wood.

The metal plate that comes with the u-bolt goes on the outside of the hull. Caulk is used under the plate.

The motorboard is laminated from plywood to a thickness of about 1.5 inches.

Essentially any plywood can be used: two layers of 3/4 inch; six layers of 1/4 inch; eight layers of 3/16 inch, etc.

For my boat, I used two layers of 5/8 inch cdx-grade construction plywood, and two of 3/16 inch luan for the outer layers.

Finish size is 17 inches tall and about 19 inches wide. But the lamination you glue together should be at least 19" X 21" and then trimmed to size later.

The bottom edge of the motorboard is cut to a 12-degree angle.

Once all the bulkheads, girders, coamings and glue blocks have been installed, it's time to seal the interior of the hull -- those areas that will not be accessible once the deck is in place.

I used latex paint. Oil-based paint or varnish or epoxy resin are also excellent choices.

Two coats of paint or varnish, or one coat of epoxy are probably enough. Pay particular attention to areas where water may sit for a while -- generally in the sponsons at or near the transom, and in the cockpit at or near the motorboard.

GT Pro rules require at least three cubic feet of foam flotation.

Three cubic feet of flotation will be enough to support approximately 180 lbs. (60 lbs./cubic foot), which should be plenty for this boat with the maximum recommended power.

"Pour foam" comes in two parts and is literally poured into place where it expands and cures. Line the area to be filled with plastic sheeting. After the foam has cured it shrinks back somewhat. Any part of your boat that the foam has adhered to will be distorted or damaged as this process takes place.

The spaces in the sponsons, between bulkheads two and three (on both sides of the boat) offer plenty of space for about 3.6 cubic feet of foam. So even if these spaces are not totally filled, it should be plenty.

For my EZ Tunnel, I used styrofoam board (sometimes called "bead board") for flotation. I tested its flotation qualities and found that one cubic foot of foam board will support 65 lbs.

One sheet of one-inch foam board will yield about 2.7 cubic feet of material.

Cut the foam into pieces that will fit neatly into your hull and will not be able to slip through the lightening cut-outs.

Beads of foam tend to easily break off the cut edges of this kind of foam. To control this, I sealed the edges with a heat gun.

NOTE: Before proceeding with the decking, check one more time to see that there is no twist in your hull. Once the deck is installed, that twist will become permanent.

If all has come out as called for in the plans, your deck should be just under 24 inches wide from the hull side to the coaming. This will allow you to make efficient use of a 48-inch wide plywood sheet.

There are different ways to cut plywood for the deck. The following description is the way I did it for my EZ Tunnel.

The first piece of deck is "L" shaped. Start laying out the L by drawing a line right down the middle of the long axis of a sheet of plywood.

The foot of the L must be long enough to reach all the way to the bow (plus just a little bit extra, to be trimmed off after installation) and extend aft between the coamings about six inches.

The L must be wide enough to reach all the way over to the outboard face of the right-side coaming.

The slot for the left side coaming is 1/4 inch wide (or whatever the thickness of your coaming), and the notch for the right side coaming is the same.

The part of the decking that extends in between the coaming will be supported along two edges by the glue blocks installed on the coaming earlier. The aft edge of this part of the decking will need a glue block approximately 17 inches long added for support.

The piece cut out of the sheet to make the L will do nicely for deck section #2. The remaining deck pieces can be cut from a second sheet of plywood.

Deck sections 1 and 2 temporarily tacked in place.

Join deck section 2 to deck section 3 with six-inch-wide butt blocks.

Join section 4 to section 1 similarly -- although you may find the joint to be too close to bulkhead four for a full width butt block. Make it as close to six inches as space will allow.

Final assembly of these joints can be done in place while you are installing the deck.

The completed deck.

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