Got to spend a bit more time on it this morning. Ground back the large and small holes and opened up another next to the small hole + lightly touched shallow chips in the gel coat along the keel. Ended up chasing the separation along the keel line for the 3 holes (one new). I'm wondering if the separation on the new hole is layup related, some of the resin is very smooth as though there was no adhesion between layers to begin with.

New hole (small hole to the right)

Here's the large hole

small hole (to the right of the new hole)

Where I need to apply glass I will feather out 12:1 once a find something less agressive than a flappy disk on the grinder. Changed to P120 and it still stripped out the material very quickly. Will do some research and see what I can find.

One thing of concern I came across was a small amount of moisture coming out of a couple of keel screw holes 1/3 from the stern. I'm thinking water is soaking through the keel from the inside. The floor is definately leaking as water pisses out the bung hole everytime it rains. I'm guessing its leaking through cracks in the gel coat, as I've put sealant in any screw holes that I could find. Maybe its time to pull the floor up and have a look?

I got the keel strip off today and poked a 0.25mm feeler gauge around. The large hole has 8mm of separation under the keel band area and nil up the side of the keel. the smaller one has a few mm of separation. I'll get some disposable overalls then get into sanding it with the angle grinder.

Kandew - Thanks for the offer, I have some other structural repairs to make so will order a bunch of resin, double bias, csm etc once I know what I need.

Bertiesdad - Lawn space is at a premium and would have to remove some plants to roll it. Even then it would be tight without moving the boat back while rolling. When you say mix things a bit stiffer do you mean upping the catalyst or using an additive to thicken it up?

I brought some selleys marine sealant so I can put some of that in the holes when I put the keel strip back on.

I don't have a flexi palette knife blade but I just thought of my feeler gauges, they are quite flexible so I will try them tomorrow.

Got close to getting the keel band off today. I've made a timber frame on the trailer to support the boat once I jack it up. Just need to put carpet on the timber supports, jack boat up and screw it into place.

Space is a constraint and I don't have any lifting gear so flipping the boat at my place without wrecking it would be difficult. I could really use proper high stud garage about now. I'm thinking that once the keel band is off I'll have to aggressively strip back the fiberglass till there's no more separation and do a proper repair. I've got a 125mm P80 flappy disk on my grinder that will make short work of it. I'll jerry rig something to provide heat so I can use a polyester resin to complete the structural repair and use epifill for fairing.

Pulled a couple of keel screws too. Appear to be stainless, so I'm guessing they have been replace at some stage as originals are brass I believe? Only pulled three and they tightened back up solid.

Ok I haven't got the dremel bits yet but gave it bit more of a cut back with a stanley knife.

Yes its the keel band see the pics below for a better view. Looks like the layer underneath is woven. There is a similar damage further along the keel that when I started prodding opened up just like this one (top two pics).

I was also thinking the keel band will have to come off as I started to scratch way at it. I want to prop the boat up on the trailer so I can remove it, will see what I can come up with/jerry rig. 

The boats not trailered right so the keel strip will have to stay for the time being. Fixing up the rollers and boat position is another item on the list.