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The hole sizes are mostly dependant on what size you tip is that will be insert and resin/ epoxy injected. You want it to fit snug without having to apply to much press as if you do it will be almost impossible to inject the resin/ epoxy as the tip will be pressed against the foam.
If clamps aren't an option you could get a few cheap ratchet straps and connect them together until they will loop around the boat (port over to starboard, underneath hull and back around to port). I did something similar to that on some loose fiberglass on the hull. It worked great.
http://s355.photobucket.com/albums/r4...2_3264.jpg
If you notice I used a flat stick/ board to distribute the clamping pressure, the vertical stick was to help the strap actually apply pressure. To date it has still held but unfortunately it really hasn't been long enough for a fair judgment (4 months) but I have no real fear that it will fail.
Yes the solid knock sound was back instead of the dull thud.
You also don’t necessarily have to do the entire area at once, wherever the resin stops will be the next batch starting point.
On proximity of hole location, I think I did something like 3-4 inches at each end and closer to 4-5 in the central area of repair. I placed a hole high on the area to be bonded and another low to the left and/or right of above hole. I squirted in the bottom until it came out of the top or at least when pressure was applied it would come out of the top. Just be ready to catch a fair amount of resin as it is squeezed out. You may want tape off with plastic area below repair then it wouldn’t be that big of an issue.
If you can’t get the resin into an area and are getting close to end of workability of resin, don’t worry clamp it let it dry then come back do a sound test or press in a little to see if it depresses. It might take of itself; it will be hard to get resin in every little void.
I’ll tell Odin (the lab) you said hi. Labs are definitely my favorite K-9. My previous lab was a 12 year old Black stubborn goober, Odin is in a close race to take the goober title.