My '82 H16 had a soft spot on inside front port hull, which was 32" long, and from 6" - 10" high. It flexed 1/8" or more when I pushed on it, and the sound difference when 'thumping' it with my finger was noticable.
I just finished a GIT-ROT repair as per Matt's FAQ and am very happy with the results. I'll make some observations for those who have this kind of repair ahead of them.
1) I used almost all of the 32oz GIT Rot that I bought from Jamestown Distributors.
http://www.jamestowndistributors.com/us ... age%7EGRID. Cost $50.00 but well worth it.
2) I followed the FAQ. After drawing the soft spot on the hull, I used 2" masking tape to cover the entire side of the hull and about 18" beyond the spot to be repaired. I could still see my pencil marks thru the tape, and remarked it. I ended up with a fair amount of GIT-ROT seeping from the breath holes, and having the tape on the hull, made clean up a breeze.
3) I removed the hull from the tramp -- which was much easier than I expected it to be. I loosened the tramp cord, and the dolphin striker, removed the 2 bolts, and it came out of the fittings easily.
4) From trial and error, I found putting the hull on the ground, not on saw horses, with the side to be repaired as close to horizontal as possible, helped the epoxy seep to all the breath holes.
5) I drilled my breath holes with a 1/8" bit, about 1/16" inch deep with a cordless drill. Going slowly it is easy to sense when you've penetrated the outer hull, and to stop. On my boat the foam core was about 1/2" thick, I used a sharp nail to push by hand thru what foam there was, to just touch the inner hull. It was pretty easy to tell where the foam was tight vs. loose and soft. I drilled by breathe holes about 6" apart.
6) I drilled the applicator hole, more or less in the center of the spot, with a 1/4" drill. Just a shade larger than the nipple of the applicator bottle.
7) I mixed the epoxy in the supplied applicator bottle, and squeezed it into the applicator hole. Within a few minutes, on the 2 or 3rd bottle of epoxy, it began to seep from a couple of the breathe holes... I was surprised and pleased to see it seep from a breathe hole that was almost 18" away. I had thought I might have to drill 2 applicator holes because the area to repair was so large.

Even though I covered the holes that were seeping with tape to 'close' them, I still had to tilt the hull, and use gravity to get epoxy to seep from all the holes. Eventually it did.
9) Lessons learned : cover your floor with plastic, prepare to have the hull horizontal, and well balanced and supported. Use the masking tape to cover the hull before beginning.
10) The repaired areas is solid and hard, with no flex. Feels and sounds like the rest of the hull.
11) I plan to cover the holes with putty, and see what it looks like.
12) I did this repair in my garage which was about 60 degerees.
The whole project took me about 4 hours. Thanks to everyone on the forum for the suggestions and posts about delam repair. Nice to have the piece of mind of having this hull fixed.
I've got an article that I found online about adjusting the dolphin striker, as this seems to be an important adjustment.
Now all we need is warm weather. I