so i have to make a hatch 66 inches long by 78 inches wide.
5.5 x 6.5 = 35.75 sq ft divided by 9= 3.972 sq yd, call it 4

1 sq yd of 1708 needs approx 1 qt of ve, so 1 layer 4 sq yd needs a gallon and 5 layers needs a 5 of ve

how flimsy would 5 layers be ?
would you use a different material ?
what surface material ? ounce and a half ?
how much gel ?
gel to be shot on after like a repair

mold is gonna be a total combat job, 3/4 ply frames on 16.5 centers,scribe cut port to starboard, skinned w/ 1/4 ply, skinned w/ 1/8 masonite and released waxed

wow, thanks

i have enough 1/2 marine ply set aside to tab in front to back or side to side kinda like floor joists for strength

Can't answer your questions to most, but I made an engine hatch for a 27' Magnum and it turned out very good.... did it the male mold way rather than constructing a female mold.
I used balsa coring with 2 layers of 1708 on top and bottom..........it's actually building a slightly smaller replica hatch in place and then covering the replica with release agent &
adding 2 layers of 1708 after cured I popped it.... I then filled the core with 1/2" balsa and also added around the perimeter 1/2"x 6" marine ply for thru bolting then finished with
2 layers of 1708.........I skim coated with filler & sanded till absolutely smooth then gel coated..........I used ve resin..........If you like, I have some pictures!

thanks, yeah put some pics up scipp

i thought a combat mold would be faster ( layup ) my hatch is curved left to right, so for me to stick build it i'd have to scribe cut some 1/2 ply (floor joists) and tab on divynicell (decking) or similar foam a piece at a time, then when it was all tabbed up underneath i could put it in the dining room and glass it up.

still undecided how to make it, but it's a done deal now, it's gotta get made

Here are some photo's I took along the way to fabricating my engine hatch.....First I built a replica hatch in place (a male mold) dimensionally smaller all around with the exact curve or crown.
The top of the hatch was melamine 1/4" material for ease of bending to copy the curve..............you can see the green release agent on the top just before the first layer of 1708 went on.

more ........

And more........

Nice work Pete!

thank you scipp, that's exactly what i was hoping for,
so you let the first 2 layers cure ? popped it
turned it over, added the core, then glassed the bottom ?

very nice work, obviously a craftsman,
thanks,
dan

Rob and Dan thanks!......................because my 27' sport had no engine hatch when I bought her and there were no Magnum sports around to pull a mold from,
I had no choice but to build a male mold........................................now if anybody needs a 27' sport engine hatch I can pull a mold from the one I built!

wow...I wish I had your skills scippy!!!! I have done some glass repair work to water muffler on my sea ray, but....nothing what U did here!!!

nice job....wish I understood more on glass work.