Fiberglass over Foam construction?

[MikeDrz]

anyone ever consider this method of construction?

check out this link sure seems like it would work for a tear...

http://www.rqriley.com/frp-foam.htm

[angib]

As a way of increasing the amount of work to build a teardrop body, maybe 10 times, fiberglass over foam is an excellent choice.

The work to get a decent surface finish with this method is enormous. Most teardrop shapes contain only flat or single-curvature panels so bending 'pre-surfaced' sheet material makes more sense.

Andrew

[MikeDrz]

I was more thinking about weight, since this method would seem to be very light.

As a way of increasing the amount of work to build a teardrop body, maybe 10 times, fiberglass over foam is an excellent choice.

The work to get a decent surface finish with this method is enormous. Most teardrop shapes contain only flat or single-curvature panels so bending 'pre-surfaced' sheet material makes more sense.

Andrew

[Gaston]

the outside of my trailer will be covered with 1" rigid foam (pink board) and then glassed. I"m doing it this way so I can sculpt the fenders and have rounded edges and corners (to mock the profile of my PT cruiser). It is a very expensive way to finish a trailer. my build is 50" tall 74" wide ( outside of wheelwells/fenders) and 120" long. You have to use epoxy as polyester will eat the foam. So the cost for just the fiberglass,(2 glass layers and 1 unidirectional layer) , + 5 gals of epoxy come to about $1300.00 plus another 200.00 for filler, $150.00 for urethane primer and $300.00 for color coats and clear to finish it. If the cost isn't enough to discourage you, try fitting a hatch between side walls covered with an inch of foam board, then cover the hatch with foam board, sand to shape and figure a hinge arrangement that will work with it all Oh yea I forgot to mention the 3 gal. of epoxy ($300.00) to glue the whole thing together and the challenge of fiberglassing 220 sq ft of trailer with 3 layers of glass and most of it vertical and trying to fall off and the endless hours of sanding foam, fiberglass, fillers and paints. If you still want to try it see my album for the parts I have so far (the foam will be epoxied over the foam on the walls) I will post pics of the whole process as I build it.

[critter]

hey all,
with that much work involved why not build a mould like in a fiberglass boat and hand lay the outter shell first? i never tackeled anything thing like that just seams like theres gotta be abetter way!jmho

[Guy]

Dear Gaston,

That seem like an outrageous amount for the glass and epoxy. Try Larry at www.raka.com.

A large number of members have dealt with him and he is extremely well thought of and his prices would no way equal that amount. His uni is 10 oz and 50" wide and still costs only $8.75 a yard.

[angib]

I was more thinking about weight, since this method would seem to be very light.

Yup, this is probably the lightest way to build a trailer body - it's what is used on super-light racing boats.

But you could get close to this weight by laminating thin plywood skins onto a foam core and have almost none of the finishing work.

Andrew

[Mitheral]

This is my plan. If you use urethane foam instead of styrene you can use polyester instead of epoxy resin. Polyester resin isn't as waterproof as epoxy but a TD isn't a boat either. Many of the guys building TriMags are using only two layers of glass.

Urethane foam is also a little flexible allowing you to curve sheets instead of having to cut relief grooves to bend a curve. I plan to double curve the front and make use of the easy mouldability of the foam base to build stuff like frenched mounts for the lights.

Advantages: fibreglass is easily repaired and fairly forgiving compared to say Filon. It won't rust/corrode or rot. Lends it self to curvy shapes like compound curved side walls. You can also carve decorative features like say a trailer name directly into the side walls or by applying a foam appliqué.

But the key advantage for me is the light weight. I intend to construct my TD such that it can be removed from the trailer allowing use as a flat deck utility trailer.

[GPW]

You guys need to learn about Vacuum Bagging .... easy , gives perfect surface(like glass) and makes the entire sandwich into ONE unit .... STRONG .... It's a wholly different method , but produces the results you are looking for ... and is not impossible for the homebuilder...

[kirtsjc]

You guys need to learn about Vacuum Bagging .... easy , gives perfect surface(like glass) and makes the entire sandwich into ONE unit .... STRONG .... It's a wholly different method , but produces the results you are looking for ... and is not impossible for the homebuilder...

Please provide a link to the technique; I will consider it since I am still in the planning stages.

John

[toypusher]

John,

Here is a link to get you started: http://www.bertram31.com/proj/tips/vaccuum.htm

And one to buy equipment: http://www.tapeease.com/vacuum_bags.htm

[asianflava]

I initially wanted to bag the sides of my tear but I figured it would be more hassle than it's worth. It's relatively easy for small parts but for big parts it can be a pain to seal. I told myself, maybe next time after I get the first one under my belt.

[angib]

And don't forget the poor man's vacuum bag - throw a sheet of heavy plastic over the job and then shovel a good depth (a foot?) of sand or more of dirt on top.

Andrew

[Bob Olszewski]

This boatbuilding site has a lot of info (including the process Toypusher mentioned.

http://www.boatbuilding.net/

[mikeschn]

And don't forget the poor man's vacuum bag - throw a sheet of heavy plastic over the job and then shovel a good depth (a foot?) of sand or more of dirt on top.

Andrew

I don't know if I can afford all that sand...

I might have to consider jugs of water instead.



Mike...