I just got Friendship back in the water for the summer last week and when I was getting her rigged at the dock someone ( OK me) sat on the acrylic top of the sliding hatch. This has been a weak point for seven years since I initially built her and it amazes me that it has taken this long to break it. Cutting to the chase, the replacement acrylic was going to cost $136 and wouldn’t be any stronger than it was before. I’ve never liked the plastic thing but it did give me a little more light inside. Verdict: Make a wooden top for her that you can stand on if you need to.
So here’s a shot you may have seen in another blog describing the new marquetry panels in the cabin doors. If you look closely you can also see the duct tape on the acrylic hatch cover. Oops!!
I decided to make the new cover the same way the hull is built, in cold molded cedar. This will produce a very strong yet light and quite thin curved panel. The hull itself is only about 5/8” thick so I’m thinking three layers of 1/8” each should provide the strength I need. Here is the light mold I made up to form it over. It’s not strong but will stay in shape if it is clamped down while applying the cedar.
With the 1/8” plywood skin in place I re-sawed some of my special old stock cedar into the 1/8” pieces I would need.
This is what I mean by “special old stock”. I count forty grains in the inch between 19 and 20. Maybe you will get a different count, but you have to agree this is special wood.
The first layer is applied with just a couple of brads at each end and the joints glued. (There’s waxed paper over the mold) Tape keeps the joints aligned for a few minutes while the glue tacks up.
The second layer is laid up at an opposing angle and stapled down with metal staples. These are removed after the glue has set.
I installed the third layer with plastic staples because I had them and it was such a PITA to remove all the metal ones. I didn’t use them on the second layer because they are 3/8” long and would have been a lot of work to sand off on the inside.
Once the glue has cured any unevenness is taken care of easily by a coarse sanding with a long block. You may notice that each of the layers arches across the curve rather than having one run parallel to the centerline and the other two arc across at 90 degrees. Having all the grain crossing the curve will make it stiffer. You may also notice that I’m using hot hide glue. (I wonder if this is still cold molding?) It is the cheapest and most convenient and I’m not worried about it getting wet because it will be epoxy sealed when complete. Also, it will have no “spring back” when it comes off the mold.
That’s about it for the structural part of replacing the acrylic piece. Next time I’ll get into the aesthetic part.
Thanks for looking in.
-- Paul M ..............If God wanted us to have fiberglass boats he would have given us fibreglass trees. http://thecanadianschooloffrenchmarquetry.com/