# Boat fiberglass on aircraft?

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##### Well-Known Member
Can I use boat fiberglass on aircraft? I am thinking it has humidity, fire and low temp/high temp resistance.

#### D Hillberg

##### Well-Known Member
It's not the glass you worry about it's the resin or epoxy

Sure. Just think of weight and lay up

#### MACOWA

##### Well-Known Member
Supporting Member
"Boat fiberglass" ? This encompasses an enormous range of materials, applications, and processes, to achieve the desired physical properties needed for each part of every design. large competition sail boats and their sail plane counterparts share striking similarities both in design and construction. It might take a little homework but a solid understanding reenforcing materials and the matrices that bind them together is required ! books sold by Aircraft spruce are a good place to start, also some of the earlier writings of John Wills can prove to be invaluable.

#### User27

I would ask why use "boat" fiberglass? Airplane fiberglass is not expensive, I bought a 100m roll 280g/m^2 92125 a few weeks ago for around £2.50 ($3.00) per metre. #### bmcj ##### Well-Known Member Supporting Member When you say “boat fiberglass”, are you asking about the mat (cloth) or the resin (liquid)? Marine mat can be woven glass or chopped glass (short fiber). Chopped is totally wrong for aircraft structures. Woven glass depends on the fiber and weave pattern. Marine resin is, more often than not, polyester resin. It has different properties (weight, strength, flex and thermal) than the typical epoxy resins. Both have been used on aircraft, but you have to consider the differences when designing. DISCLAIMER: I don’t have extensive experience or knowledge of composite structures, so feel free to call me on any errors in my post. #### Norman ##### Well-Known Member I don't know about the current situation But "boat glass" used to mean fiberglass sized for polyester resin, whether woven or mat. The sizing is a chemical treatment that improves the adhesion and is specific to the type of resin. If the manufacturer says it's for use with polyester DON'T use it with epoxy, the fiber/matrix interface will be weak. Also the stuff you can buy in hardware stores that's folded is not fit structural material for airplanes because the inner layers are folded too tightly and the fibers are probably cracked. #### TarDevil ##### Well-Known Member Marine resin is, more often than not, polyester resin. Depends. True of many older fiberglass boats. Most home boat builders use epoxy resin. All my boats are. #### bmcj ##### Well-Known Member Supporting Member Depends. True of many older fiberglass boats. Most home boat builders use epoxy resin. All my boats are. Good to know. I worked part time helping a buddy in his boat building shop in the 70’s making bass boats and ski boats. We used polyester resin in ours (I used to love that smell… I love the smell of Bondo too). Last edited: #### TarDevil ##### Well-Known Member Good to know. I worked part time helping a buddy in his boat building shop in the 70’s making bass boats and ski boats. We used polyester resin in ours (I used to love that smell… I love the smell of Bondo too. I gave up on poly after two transom cores turned to mush. It just doesn't stay bonded to wood. Last edited: #### Rik- ##### Well-Known Member I'll let you in on a little secret. There's no difference and really no such thing as "boat fiberglass" and in fact if you've ever used FG, it was the same thing that people use on boats, cars, aircraft, lawn equipment and so forth. It's like looking for a LH screwdriver. #### Fiberglassworker ##### Well-Known Member I would ask why use "boat" fiberglass? Airplane fiberglass is not expensive, I bought a 100m roll 280g/m^2 92125 a few weeks ago for around £2.50 ($3.00) per metre.
Who are you buying that from? That stuff from Interglas geweb is \$6.00 per yard in the USA.

#### MACOWA

##### Well-Known Member
Supporting Member
Can I use boat fiberglass on aircraft? I am thinking it has humidity, fire and low temp/high temp resistance.

Can I use boat fiberglass on aircraft? I am thinking it has humidity, fire and low temp/high temp resistance.
Put "Americas cup technicalities" in your search engine. The video gives some insight into the AC75 class race boats. and their construction. Boat glass indeed !

#### BJC

##### Well-Known Member
Supporting Member
I'll let you in on a little secret. There's no difference and really no such thing as "boat fiberglass" and in fact if you've ever used FG, it was the same thing that people use on boats, cars, aircraft, lawn equipment and so forth.
Well, there is E glass and S glass .....

BJC

#### Bob H

##### Active Member
Aircraft grade glass has fiber bundles (tow) of controlled size woven into a cloth with relatively the same number of tows in both directions. The smaller the tow size, the stronger the laminate. Normal 7781 glass has a tight, orthogonal weave and is approx 10 mils in thickness, dry.
It is the standard woven material in structural designs. It has epoxy sizing for good matrix adhesion.
Polyester resins used on boats are cheaper than epoxies so boatbuilders use plenty of it because they are building up mass and want to keep costs down. Epoxies have higher temp resistance and provide a stronger laminate than polyesters. If you are making an aircraft structural part or repairing one, always use an epoxy matrix. Aeropoxy from Spruce is a good 2-part system with high mechanical properties at reasonable cost. The West Systems work also.

#### proppastie

##### Well-Known Member
Supporting Member
Might depend on if it's structure or non-structural as to if you need the high priced stuff

#### Rik-

##### Well-Known Member
Well, there is E glass and S glass .....

BJC
And.. Like does the fiberglass know what it is being used for?

#### Norman

##### Well-Known Member
And.. Like does the fiberglass know what it is being used for?
The stress strain characteristics of E-glass are much different than S-glass and it's not quite as strong. Sure you can use E-glass (the older EZs have E-glass spars) but the parts will be heavier and more flexible that an S-glass part designed to the same strength. Beats the hell out of wood though and way cheaper than aircraft grade spruce.

#### Bille Floyd

##### Well-Known Member
Well, there is E glass and S glass .....

BJC

YES , you are correct ; but Not all fiberglass is chemically treated
to accept Epoxy . It's kinda a Big thing to consider ; screw it up