August 4-12, 2003

A long week of "planking" the sides and bottoms with the first of two 1/2" layers.

Difficult to photograph in such tight quarters.

I've also been considering auxiliary power. I really don't want an engine-even an outboard. Sculling and poling should be enough. Research so far seems to indicate a yuloh-type sculling system would work well. We'll see about that later on.

August 19, 2003

Before the next major construction step-laminating the second layer of 1/2 inch plywood onto the hull, I thought it would be a good idea to test the method I mean to use.

Building Test Lamination

1) Two identical pieces of plywood are cut. In this case, 18 inches by 18 inches. The upper board is marked for screw, nail, and air bleed hole locations. The lower is marked in a 1 inch grid which will allow for coverage testing.

2) A measured amount of thickened epoxy is poured into the middle of the lower board. I did this in two smaller batches. The goal is to not quite have enough to cover the entire area-this should give an accurate measure of coverage with this particular trowel.

3) The epoxy is spread out in all directions with a toothed trowel.

4) When a uniform distribution is achieved, record which of the squares on the board are not covered with epoxy. A three-squirt batch of West System covered 273 square inches before squeeze-out.

5) Diagram of nail and screw pattern showing coverage of epoxy. Shaded areas were uncovered.

6) Positioning the boards.

8) Ring shank nails are driven into the remaining locations.

7) 1-1/4 inch fine-thread drywall screws are driven in every other 6 inches, staggered from row to row.

10) The completed test boards.

9) The boards are turned over and the points of the nails given a tug with a pair of pincers. As none of them moved at all, this step will not be necessary in the boat. What will be necessary, however, is to drill a pilot hole for each nail as there is a fair amount of split-out on the back side.

Destructive Testing

Step 1. Saw the test piece into strips down the centerline of the grid marked earlier.

Step 2: Examine the bond for voids and unglued sections.

Step 3: For well-bonded sections, try to break glue bond with a chisel and hammer

Step 4: Compare bond quality with coverage of epoxy diagram

Shaded areas indicate no bond occurred. Compare bond failures to the coverage sketch above.

Conclusion

Except in those areas where the epoxy did not cover at all, the bond is tight, void free, and almost indistinguishable from the plywood bonds themselves.

The lamination split through the wood layers, not in the glue layers.

The method of glue spreading, nailing,air holes, and temporary screws works well.

A bit anal-compulsive? Perhaps. But that hull is what separates me from fish-bait.