Moth Fixing

What? Fixing the Moth's foredeck

   

   

   

   

   

   

My dad, back when he was a young and keen sailor, bought himself a Moth. He couldn't sail it, he just went out for capsize practice ;-) One winter he was saved from further embarrassment when the boat got damaged in a storm by a fallen tree.

In an unfortunate repeat of history, 20 years later my Moth also suffered damage from a fallen tree. Except this time I was the one cutting it down..... Idiot.

A small part of the tree fell, landed on the shed, bounced down the garden and ended up embedded in the foredeck.

What worked:

Orbital sander, 80 grit. My bosch orbital sander worked great, as usual. Sanding was a breeze, I got the surface prepared quickly and blended the ply in after bonding. 80 grit worked much better than 120grit, although both blunted fairly quickly with the paint.

Cardboard template. Getting the shape right was simple. Hack the cardbaord to shape then use it to markout the plywood. 

Ratchet straps as clamps. The ratchets worked well to get lots of clamping force, compress the glue joints and bend the plywood. I've got some 12" G clamps but even ones that big were useless on this job.

Vac bagging film as release film. I didn't want the glue to get on the straps. It released well.

Clamping supports (Load spreaders). Using 1/2" x 3" strips of softwood helped spread the load and compress the whole joint.

Shed as an oven. I was worried about the weather turning cold and the glue not curing properly, so after assemble I shoved the whole bow of the both into the shed, along with a fan heater, external temperature sensor and sealed it up with some bubble wrap. Several times during the evening I turned the fan on a for a few minutes to keep the temperature above 10degrees. I'll definitely do that again. The glue was cured enough to hold but soft enough to cut with a knife so would have been ideal for getting future layers to bond to. I'll definitely do that again, although if I wanted it hard enough to sand I'd probably try to keep the temperature above 20 degrees.


What didn't:
2mm plywood. Before ordering anything I measured the thickness of the original at 2mm. In retrospect I should have subtracted something for the several layers of paint that are on there, as the 2mm stuff is much thicker/heavier than the original. It was more awkward the necessary trying to get it to bend. At least it will be tough. It needs to be as a cheaped out and bought regular birch ply rather than marine grade, so any cracks could lead to disintegration. I'm going to fully coat it inside and out with epoxy so it should be ok.
Not using load spreaders. Straps on their own didn't compress the joint enough.
Not enough filler
Not getting the film flat/smooth. I didn't smooth out the release film and found that the resin was very rough over the surface after curing
Bending cardboard perpendicular to the corrugations. In retrospect I should have orientated the cardboard differently before I start hacking it. It was quite difficult to get it to bend evenly when I was trying to double check I'd got the shape correct.
Weather. I did this fix on a Saturday when it was forecast to rain, and the worry made me rush a little. I got it done but it rained all of Sunday, meaning I couldn't get all the finishing jobs done. In my defence it was probably the only weekend I'll get between now and March when the temperature at the weekend is above +10C during the day.