Hull Repair
Tom Pike, who owns an ENIGMA with a cabin, suggested to me that it might be helpful to others if I described how I repaired the hole in my tiny little micro-cruiser. Therefore, I took a lot of pictures and made a webpage to document the process. In retrospect I don't think the restoration was particularly difficult, but it took longer than I expected it would to fabricate a tight fitting wood patch. Fortunately, both Matt Layden and Jacques Mertens from E-boat in Vero Beach provided me with plenty of marine plywood scraps so it didn't cost me anything to make a few extras until I got it just right.
To begin with here is a picture of the grey boat that hit poor ENIGMA. To be honest, I never thought that a rowing shell
could do so much damage; but when you consider it is 40 feet long by
16.5 inches wide and was powdered by 4 strong teenage boys, then it's
basically a 700 pound carbon fiber spear.
The
first thing I did was cut away all the delaminated wood. I guess I
could have removed even more material for a cleaner opening in the end, but I was
a little concerned about losing the curvature of the side if I took too
much away.
Therefore,
I cut and ground off what I thought was the minumum amount warranted,
and I did it in an oval pattern to make fitting the wood easier..
Next I beveled the outside about 1-1/2 inches in, and I got around to making the first of three wood patches.
I began by placing a sheet of plywood over the hole, matching up the grain and then tracing the hole from the inside.
I created a quick pattern of the outside repair area from clear 6 mil plastic, and then I placed
this template over the plywood with the inner lines already drawn.
After cutting out the filler piece, I put it back over the hole to make sure my
inside lines still matched up exactly. Then I took it to my grinder to
make lots of saw dust and a rough bevel.
I
finished up the bevel by hand and rechecked it on the hull. With
everything perfectly in place, I drilled two 1/16" holes 1-1/2" from the
edges to make aligning the pieces easier later on.
I
painted on West System epoxy to both the bevels on the patch piece and the
hull, and a few minutes later I added a thickened mixure of epoxy and
cabosil to the hull.
The
patch was then mated to the hull and held in perfect alignment
using 2 nails in the holes that were drilled earlier. Lead weights were piled on
top to hold everything down flat and even.
Underneath
I used a selection of wood sticks, hiking poles and even an old camera
tripod to support the inside of the hull and the thin beveled edges.
When
the epoxy cured I ground the edges of the patch level with the
surrounding outside surface, and I sanded the patch slightly concave to
make room for the upcoming fiberglass cloth covering. If I had to
do it again I probably would undersized the perimeter of the patch a bit
more so that it would naturally have sat deeper from the very
beginning.
Then
I glassed the outside with 3 layers of tight weave 3.25 oz glass, and I finished it
off with a thin layer of microballons mixed with epoxy. Since Matt used 2 layers
of this style of cloth in the original construction, I figured the extra layer
of glass would give me something to sand into later on when I was
making everything smooth.
On
the inside I used multiple layers of plain weave 4 oz glass followed by 2 layers of
3.25 oz glass to bring the new surface of the patch level with the
surrounding wood.
After
all the glue cured hard, I sanded both sides of the patch flat, and I
filled in any pin holes or low spots with additional epoxy or filler as
needed.
Now all I have to do is paint.