Over the winter I am renovating my 2600 AO to include filling in some old rigging holes. I have read just about all the internet has to offer around patching holes and filling in gelcoat cracks, only to find there is always 10 ways to skin a cat. I'd like to ask the experts here (ahem...GlassDave) on what their perferred method is and why.

Fiberglass patch:
I have some holes left over from vents and other old rigging that I plan on replacing/moving that I have access to the back of. The two main methods I read up on are pretty much the same, with the exception of which side it is done from. Grind out an area around the hole with about a 1:12 ratio of the thickness of the patch, layout patches, largest first building up until desired thickness using subsequently smaller patches. My question is: Is it better to be done from the inside, using a backer on the outside to enure that the surface is flat once the patch has cured. Or reverse, grinding and patching from the outside with a backer on the inside? I question the first method as I would think it could crack around the edges easier this way.

Here is a picture of one of the vent holes I will be filling.


Gelcoat cracks:
I have a few spots over the deck that has slight cracking in the gelcoat. I have planned on just dremmeling these out using a small bit to v-groove them and fill with thickened vinylester. Any reason I should handle these differently and if so how.

Cracks:

JBrock,

I'm sure Dave will have the best solution to both of your repair questions, but to the first, I just did a simular repair to my mag dash (filled in a 5" X 8" cutout where radio was)
Like yours in the picture the back was acessable so I worked from the inside. Scarfed 12:1 around the inside edge - taped a piece of 1/2" plywd flat to the outside surface
with a plastic sheet for a smooth form..then from the inside, I brushed a liberal amount vinylester resin (to the smooth side of ply with plastic sheet) then with precut patches of 1708
I started to fill in starting with small to large until thickness was achieved..........next day, (from the outside) I grinded all the edges where the new and old fiberglass did meet.
this created a nice depression to be filled in with a polyester filler...........the whole surface then was skimmed over a few times and sanded ...........I primed and painted to finish.

Thanks for the input, Scippy. I'm fairly certian that this is the route I will take, it seems like this method will be the best from a final firing on the outside stanpoint.

the vent holes would probably be best off if you cut out that piece separating them and do it as one big rectangle hole. For that i would scuff the inside well with 36 and put a layer or two in there and let it cure giving you a stable back drop for the repair. After it sets up you can scarf the outside edge down for the surface laminate. Grind back a few inches making sure to knife edge the old perimeter of that hole, you want the scarf to come to a point right where the old hole was. Looks like your on the right track. The stress cracks your gonna just hafta grind away, try to group them if possible. I usually scarf them back and put a layer or two of mat on to help restore the surface and after it faired cap it with waxed gel for final surface fairing.