How Thick should a hull be ?

[CastrolR]

[quote=Fanie;271284]
There is a bit more involved in that different shapes are calculated differently from one another, the glass thickness, type, orientation and process amongst others play a role.QUOTE]

Sounds like thumb sucking to me

Jokes aside, you are right, fibreglass thickness for boat construction can be calculated up to a certain point, now dial in all the other factors and there is no hard and fast calculation, it is at this stage you have to depend on knowledge and experience, it is effectively a trade off, at one end of the scale you have a superlight construction to an overweight at the other, somewhere in the middle is the hull layup you are looking for, which depends mainly on purpose

The programmes to calculate laminates have been discussed and posted endless in many threads on this platform in the past. Use the Forum search to find them.
All of them are worth a penny if one does not know to which scantlings he has to calculate!
But to the original question again:
if that section which was measured has not been gel. only, but laminate (including some 1-2mm gelcoat), the dimension is sufficient and nothing to worry about! You could make a whole 34´boat out of 8,5mm +1,5mm gel. if the design is appropriate and the laminate done right.
Regards
Richard

[WorWilly]

Great Info guys, many thanks

fannie got the pdf great thanks....

[Fanie]

WorWilly, that's just to give you an idea. There is a lot more involved than meets the eye. You should visit a boat yard, have a look when they build a hull, talk to the builder and ask him to explain what they're doing and why. If you're lucky it may be worth the look.

Sounds like thumb sucking to me

Well maybe I am. If boatbuilding is so easy and simple then why are so many people buying these expensive things.

The idea is not to just make a hull thick enough so it won't break, there are other considerations.

Too thick a hull would be very expensive and very heavy, difficult to trailer, you'd need a bigger motor, it's going to sit too deep in the water. Too thin and weak a hull you can imagine...

If that's the idea many won't have the nice boats they have. Instead the hull shape get designed for a special purpose, then the strongest and stiffest combination of glass, layup orientation as well as method is calculated. Yes, these guys actually sit and actually calculate the stuff.

Besides, if I'm lying to you about this about a hundred forum users will jump on what I've said

[Fanie]

I forgot to mention something very important wrt fiberglass structures. If a lip or step is added in a panel it increase stiffness and strength tremendously. Note the hull shape in the last picture. That hull is much stiffer and stronger because of the step in the hull.

http://www.boatdesign.net/forums/ope...s-26910-7.html

[WorWilly]

cheer's fanie, I live on the marina LOL

and seen hundreds of hulls bing formed from a distance, but didn't know how thick they were, cheers

[Frosty]

So wheres the Marina in Newcastle then?