fiberglass cloth thickness and strength

[wet-foot]

is there away to predetermine the amount of layers of glass cloth needed to achive a certain thickness? Also strength added per layer? Also what is the glass to resin ratio with regular lay-up compared to vacuum bagging?

[Roly]

David Gerrs "Elements of boat strength" does most of that bar the specific tensile/compressive value for laminates.But he does give a recommended laminate schedule for your size boat via a scantling number.And the build thickness of various fabrics.

Also what is the glass to resin ratio with regular lay-up

Depends how diligent you are with each layer, I guess, & whether you use peelply.
I just did an epoxy layup of 810gm triaxial (4 layers) non-vacuumed and achieved 55/45% resin/glass ratio.Dunno how good that is? Perhaps somebody who knows can chime in..............
I do find that if I want a void free "peelplyed" stipple you sometimes have to add a little xtra resin on top and squeegee out. Just a tad.

[frosh]

Common wisdom says that about a 10% improvement is obtained in glass/resin ratio when going from a careful hand layup, to a vacuum bagged peel ply, bleeder cloth method. Maybe 55% resin 45% cloth to 50/50.

[marshmat]

Vectorply http://vectorply.com/lamdesign/vectorlam_sw.htm publishes a free laminate design software that works as a plugin to Excel. It's a bit tricky to learn but can calculate most of what you're looking for, for an arbitrary laminate.

[SamSam]

There is a chart here in the third reply. I would just post it but somethings not right with my computer. Sam
Fiberglass thickness

[wet-foot]

sam sam the chart really helped, thanks.