Mini Tunnel (Redesigned Version) Boat Plans
| |
My dashboard has a two-inch crown, drawn with a bent batten. It is made of two layers of 5mm plywood and is nine inches deep along the centerline. I have located the dash about 2.5" foward of the "peak" of the coaming so that the cowling deck (which extends all the way to the peak) forms a short overhang over dash. That's just a preference of mine, do as you like. The cleats at either end of the dash are glued to the coaming, but I do not glue my dashboards in place, making them easily removable for adding instruments. | |
A "steering bulkhead" is installed 18" to 24" forward of the dashboard, besides its structural role, will also carry the forward bearing for the steering system. Try to locate this bulkhead such that it will not interfere with use of a foot throttle. The curved top edge is traced directly from the dashboard. | |
The curved cleat at the top of the "steering bulkhead" should be at least an inch wide -- wide enough to accomodate the permanent decking at the forward most part of the foredeck, and also the removable part that extends from the bulkhead to the dashboard. Notches at the upper corners of this bulkhead make room for the long cleats that will be glued to the upper edges of the coamings. | |
The terminal bulkhead is 3/4" pine. The height of the curved top edge is determined by laying a straight edge along the dashboard, the steering bulkhead and the terminal bulkhead. It is beveled to match the sloping edge of the coaming and the angle of the straight edge. | |
The bottom of the cowling tip. Forming the actual tip of the cowling and the sponsons will be covered later. | |
These cleats are three layers of 1/4" strips. A single 3/4" thickness would be too stiff and would distort the curve of the coaming. | |
Step the layers upward so they can be beveled to match the bulkheads and dashboard. | |
Be sure to extend the cleats all the way to the peak of the coaming, overlapping the coaming trim at least a little bit (more is better). I didn't do this on my Laker 14 and soon realized the gap between cleat and trim was a weak spot just waiting to fail. Here I'm fixing my error. | |
The cowling deck from the steering bulkhead to the nose is permanently installed. I used 5mm plywood that had to be kerfed to make the bend. 3mm is even better and will bend in place very nicely just as it is, and will be a bit lighter as well. A ridge batten is glued to the plywood. | |
Note that this deck piece only overlaps half of the cleat along the top edge of the steering bulkhead, leaving some for the removable part. | |
The removable part of the cowling deck, which extends from the steering bulkhead to to the peak of the coamings, is also kerfed (if using 5mm or thicker plywood; 3mm will work very nicely here, too) and given a ridge batten, and also a cross member a few inches aft of the steering bulkhead. The cross member is cut to the same curve as the steering bulkhead. The cross member should not be necessary if using 3mm plywood. My removable deck is held in place with nine screws along each edge, plus two into the steering bulkhead. Alternatively, you could do what I've done on my racing boats, seen on this page. | |
This bulkhead is installed directly behind the driver's seat. For your Mini Tunnel, this bulkhead will be right on Station #4, attached to the forward face of the beam (or the aft face, if you prefer -- it really doen't matter which) and attached to the coaming with 3/4 x 3/4 cleats. Add a cleat along the top edge as well to stiffen the bulkhead. | |
|