rib hull

[grp.boat]

I am looking at building 9mtr ribs and am after some assistance on the layup.
I was going to lay it up as follows.

Gelcoat

300 g csm

300 g csm
600 g woven roving
300 g csm

300 g csm
600 g woven roving
300 g csm

300 g csm
600 g woven roving
300 g csm

and then it will have polyethelyne stringers encapsulated in 3 layers of 600 g csm before the floor going in.

[marshmat]

I take it the blank lines in the schedule indicate a "wait for previous to cure" ?
It looks a little heavy on the CSM, to my eyes. Mat isn't strong, it isn't a good structural material. It's a filler, for taking up the space between the fibres of the heavy rovings. I would think that only one layer of CSM between layers of roving should do, ie. less mat more roving. But maybe that's just me....
Is this to be cured open or under vacuum bag?

[jfblouin]

Look at http://www.zeppelin.fr/uk/frm_fab_uk.htm. Maybe too many Mat.

and this is for the Zodiac CZ7: "Hand lay-up: Hull - 54 oz. woven roving, 4 oz. chop strand mat. Deck - 36 oz. woven roving, 3 oz. chop strand mat. Balsa core in hull. 4mm. Coremat core in deck. "

That's look like:
Gelcoat
300 gr mat

300 gr mat
600 gr roving

300 gr mat
600 gr roving

300 gr mat
600 gr roving

I would think that only one layer of CSM between layers of roving should do, ie. less mat more roving.

I think so me too! Each layer will be roving over mat, no more

[oldtimer]

300 gram against the gel coat is ok I would use 450 gram instead
Why use roving ???
it is thick ,it uses a heaps of resin, and you will get print through of the glass pattern .I would be using a cloth of the same weight rather than a matt its thinner for the same weight and lays flatter = less resin . Finish with roving on the inside laminant and a layer of peel ply to help sop out some of the resin off the surface and give a smooth finish .