epoxy specifications

[mselle]

Does sombody out there knows the density (g per ccm) of glas fiber reinforced epoxy of the kind one uses for building boat hulls. I'm just playing around with modelling boats (a 8 meter and a 5.5 meter center console fishing power boat) and would like to calculate the weight of the hull and deck etc. How thick are the outer and inner walls of a boat like described and are they constant from the keel up to the hand rail?

Marco.

[Dutch Peter]

Originally Posted by mselle

Does sombody out there knows the density (g per ccm) of glas fiber reinforced epoxy of the kind one uses for building boat hulls.

These are probably build from polyester, density depends on methode of building (hand-lay-up or infusion)

Originally Posted by mselle

How thick are the outer and inner walls of a boat like described and are they constant from the keel up to the hand rail?

Are these type of vessels double skin, or do you mean glass thickness inside and outside the core.
This depends on the panel size you use, so where is your primairy structure located. From there you can calculate the skin thickness you need.

[mselle]

I am not an expert in boat building at all. I am also not really intended to build one of them. Just seriously curious about how the boats could be made. The boats, I thought, should be made out of two shells, which then will be clued together with either an expansion or floatation foam. So I thought the outer shell will be thicker then the inner one. What I do not know is whether this construction works and if it will become something stiff like a core sandwich construction.

Originally Posted by Dutch Peter

These are probably build from polyester, density depends on methode of building (hand-lay-up or infusion)

Since everything is still theoretically I have no idea if it will be hand-lay-up or infusion. Is there a big difference in density? Does the thicknesses have to be different to achieve the same stiffnes/strength?

May a little explanation, why I am interested in density figures. As one can see, the boats are built in a 3D application which allows me to calculate volumes and points of mass gravity center. If I could calculate the approximate weight of my hulls I can better define the water lines and the all over shape - since that is what I am really interested in as a designer.

I am sorry, if some questions and thoughts sound a bit strange to a prof. But I appreciate all informations I can get.

Marco.

[donjames]

mselle
I'm working on the same solutions and the specs are wide and plenty of manufactures
to chose from. I my self as a beginner have learned a great deal talking with pros and beginners alike on the forum. But there are times when the answers just don't come at the stroke of the keys. I have surfed a gazillion web sites looking for everything.
So I've resorted to the shade tree on several occassions. Simply put most manufactures will send you small samples of materials, i.e. core, glass etc.
I picked some popular systems that are proofed and true and started to weigh 1sq. ft.
at a time from the core to the first glass lay-up etc. etc. Guys .. stop me if I'm waisting time or having too much fun .... I hav'nt completed yet and don't have the final answers carved in the tree yet but it makes good since.....Huh? ..... Well?
donjames

[donjames]

mselle
I'm working on the same solutions and the specs are wide and plenty of manufactures
to chose from. I my self as a beginner have learned a great deal talking with pros and beginners alike on the forum. But there are times when the answers just don't come at the stroke of the keys. I have surfed a gazillion web sites looking for everything.
So I've resorted to the shade tree on several occassions. Simply put most manufactures will send you small samples of materials, i.e. core, glass etc.
I picked some popular systems that are proofed and true and started to weigh 1sq. ft.
at a time from the core to the first glass lay-up etc. etc. Guys .. stop me if I'm waisting time or having too much fun .... I hav'nt completed yet and don't have the final answers carved in the tree yet but it makes good since.....Huh? ..... Well?
donjames

[Dutch Peter]

Originally Posted by mselle

I am not an expert in boat building at all. I am also not really intended to build one of them. Just seriously curious about how the boats could be made. The boats, I thought, should be made out of two shells, which then will be clued together with either an expansion or floatation foam. So I thought the outer shell will be thicker then the inner one. What I do not know is whether this construction works and if it will become something stiff like a core sandwich construction. .

Yes, this works. There boats being build like this.

Originally Posted by mselle

Since everything is still theoretically I have no idea if it will be hand-lay-up or infusion. Is there a big difference in density? Does the thicknesses have to be different to achieve the same stiffnes/strength?

With infusion the glass/resin ratio is higher, which makes the laminate stronger. But also thinner, and you need thickness for your section modulus. So, eventually that doesn't really make a difference. The biggest difference is in the much smaller amount of air encapsulated and absence of toxic fumes while infusing.

Originally Posted by mselle

I am sorry, if some questions and thoughts sound a bit strange to a prof. But I appreciate all informations I can get.

Marco.

Keep asking!!


Peter