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.