Previous Page -- INDEX -- Next Page

Pro Tunnel Race Boat Plans
Page Two
Bulkheads, Beams and Stem

The four bulkheads and the transom can be cut from a single sheet of plywood.

For each bulkhead, or half bulkhead, begin your drawing with a Centerline and a Reference Line, making sure that these lines are perpendicular to each other. Note that almost all measurements on the bulkhead drawings are measured vertically from the Reference Line, or horizontally from the Centerline.

The original Pro Tunnel had only two battens along the sponson pads, which is why the bulkhead shown only has two notches per side. But two battens proved to be inadequate. Note that the plans call for two battens the full length of each sponson, and a third batten extending from bulkhead #3 to the transom.

Dry assemble each bulkhead with its corresponding beam; beam dimensions are included on each bulkhead's drawing. DO NOT glue them together at this point as they must be final assembled in place along with the tunnel sides.

The transom beam can be shaped from a single piece of hardwood, but it is more easily assembled from two (or more) pieces. In this two piece beam, the wide edge is obtained from 3/4" stock. The 1/2" x 1" notches for the tunnel battens are cut into this piece before it is joined to the remainder of the beam.

Pay particular attention to the locations of the notches that correspond to the location of the coamings and the tunnel sides. See the "Transom Beam" drawing.

The transom joined to the transom beam.

It is obvious from the photo the 3/4" stock I used was not as long as the bulk of the beam -- I most likely used a handy scrap which was "long enough." Although I don't recommend you follow my lead here, my shortcut did not compromise my Pro Tunnel. The strength of the beam is most important between the sponsons, much less so within them.

You may glue the transom to its beam at this time.

The stem can be shaped from a single piece of softwood. I used a drawknife and hand planes to shape mine, but these are tools I am accustomed to using. I suspect that most builders would choose to cut theirs with a tablesaw.

Previous Page -- INDEX -- Next Page