I used for my models all types of carbon cloth from 90g/m² very espensive up to 160g/m²
Generally the proportion between carbon and epoxy is 50/50 as has been said in previous posts.
I used kevlar cloth of 75g/m² - one particular attention, I never use this material as an external cloth- this material is very dens of micrometric fibers and do not accept sanding like glass or carbon. I got bad experience in the past. Is a good material capabable to absorb chocks and therefore very usefull if mixed with carbon that has lesser resistance against chocks. Carbon - Kevlar- Carbon is a good combination, Kevlar (inside) - Carbon - Carbon is also good, Carbon inside - Carbon - Kevlar outside is a disaster !!!
Because of the fiber density Kevlar requires more resin in a ratio of 40/60.
I used mixed cloth carbon/kevlar - similar remarks as for kevlar. It is a nice looking fiber but need to be covered with glass for final looking.
Finally I use more and more often glass of any weight, simply because is cheaper.
The spread fashion of using Carbon is not, in my opinion, justified for our models, the strenght of stailess steel is not needed. The mecchanical analysis could show in terms of efforts, that glass is largely adeguate for the hull structures.
My calculations are very simple, according to my experience, the “skin” values are in fonction of the hull lenght : The skin is given in g/dm² The skin is composed by cloth and resin.
4.5 g/dm² to 5.5 g/dm² for hull lenghts of 50cm to 80cm
5.5 g/dm² to 6.5 g/dm² for hull lenghts of 80cm to 110cm (Class IOM)
6.5 g/dm² to 7.5 g/dm² for hull lenghts of 110cm to 130cm ( class M)
These values are referred to cloths and resin on a ratio of 50/50, therefore the tissus have half of the weights g/dm² illustrated.
As an example : 4 layers of glass of 80g/m² are equivalent to :
0.8g/dm² x 4 = 3.2g/dm² . Adding an equivalent weight of resin the final weight will be 6.4g/dm². Obviously is not easy to achieve without experience in lamination. Using vaccuum some gains in weight could be obtained.
Actually a Hull of 39dm² will have a weight of 39dm² x 6.4g/dm² = 249.60g
4 layers of 80g/m² glass are much better then 2 of 160g/m²; further better strenght and waterproof is obtained.
In general the lower range I use it if carbon is employed and the higher range is reserved to glass cloths and epoxy.
In this moment I’m experimenting a new material : the cotton fabric wich weight around 112g/m².
With cotton there is a large amount of various color, and all sort of ornamental drawing.
Obviously I cannot consider this fabric as strong as glass, but his presenting the advantage for choosing a large amount of decorations, never achievables with paints or aerographs. A final cloth of glass protect the fabric.
Hope this could be of any help, this is the way I’m doing.