Fiberglass Help Please

[BowMovements]

Decided to take on the task of filling an hold thruhull transducer hole to free up some room in the bilge. I’ve been using polyester resin and a mix of csm and 1708 for the repair. The problem I’m having is not being able to get the “fabric” to stick well enough when laying it up. I keep getting lots of air pockets that won’t work out. I try pushing them out with a brush and they keep forming. The problem seems to be it sagging away from the hull, gravity pulling it off. Should I let the resin start to kick off more before laying up? Would a thickened epoxy be a better application? Any help would be appreciated. First image is where I sanded out to get a tapered area and the second image is a wet layer of 1708 showing the air bubbles.

[Toeknee217]

I believe epoxy is recommended when doing below the waterline repairs. Its not mentioned whether or not this was done  but you need to create a backing from the inside to do this correctly. It will also provide more surface area for new glass to stick to and avoid bubbles. There are a couple of useful videos on YouTube showing similar repairs. I believe boatworks today has some good videos on it. Good luck!

[HoneyB]

I think building a form under the hull and working from the inside would have been the preferred method. That being said I wonder if you could try the following. Cut a piece of plywood And cover it with wax paper.  lay your glass on the paper putting larger to smaller pieces out and work your resin into the mat. Once wetted in put the glass up against the boat on the plywood. Then use a jack or whatever to apply pressure on the form to push the air out. Let it set up and drop the form board away. 
  I think it could work 

[MuddyBottomBluz]

I will add my 2 cents since I have had more fiberglass on me then the boat I was working on, overhead ***!

What I have done is use chop strand mat / biaxial / 1708 and I make a bed/mat of blue painters tape (sticky side up) big enough to overlap the repair job by a foot on all sides.  Then take my larger patch for the entire area and wet it out on the tape, then next size smaller and wet it out, etc. etc. I press the repair patch into place working from the center out, more glass the better. The inside of the hull where the repair is taking place is open, air rises and if that is plugged the you will have air trapped. Then grab something like styro foam and cut it about the size of the repair area and put it on the bottom of the area of repair and tape tightly to the hull to apply additional pressure to the repair area. Wipe up the liquid resin that SHOULD be entering the hull until it flashes. Let dry then work on the inside of the hull.

  Letting the resin cure a little prior to lamination is not the answer. Excess resin and mat can be ground down or sanded so the excess will not hurt, better too much than not enough. Any over head fiberglass work is messy but it is part of job!