Are foamies lighter?

[spd2918]

I am interested in building a super lightweight tear to pull with my Fiat 500. I want to retain as much MPG as possible while having my own bed. The minimum specs are:

5x8 bed
doors on each side
no kitchen

How light should a well built 5x8 bed foamy be?

[GPW]

Should be able to bring that in under 500# ... Easy !!! Trailer weight is the first consideration ...

[spd2918]

I want to take a class to learn aluminum welding, but that's down the road. If the trailer body is light enough, one should be able to get away with a lesser frame.

I know the foam itself is light, but what about the covering (glass, canvas). I would think the weight saving may come there. I lean on the collective wisdom of you guys.

[GPW]

The covering is pretty light too .... usually the standard 3/4” plywood floor that weighs the most ... next to the trailer ... With an AL trailer , you can get even lighter .. perhaps build the trailer to accommodate a lighter floor , which means more trailer cross braces in strategic locations... No free lunch ... There’s always a compromise, weight vs. strength ...
Just weigh or calculate everything that goes on the trailer first ... easy way to approximate the weight ...

[loaderman]

Weight is not the only consideration.
Aerodynamics, height above the airflow of the fiat.
Enough weight or downforce to keep it on the ground.

[R_W]

A Fiat is 64.1" wide at the widest point. How wide is it at the window line? You really don't want the trailer any wider than the distance from the insides of the mirrors if you want to use them. Track width is 55", so a 4x8 trailer tires will track behind the car nicely.

It is almost 5 foot tall, so you have plenty of height to work with for a TD.

The light duty HF trailer is 221 lbs. You can lose some weight in dropping the hinges and stake pockets, etc.

If you build the floor as a SIP/ torsion box with 1x2 "joists" running BETWEEN the trailer crossbraces and a few spacer blocks on top of the cross braces, you will have a warm floor with little weight. 1/4 ply inside, 1 1/2 foam with 1x2 cedar spars, and fiberglass or canvas bottom. Use foam floor tiles throughout to protect from knees/point loads and it should work (no experience, just speculating here!) Even with fancy doors from teardroptrailerparts, weight should not be a problem until you add the beer

Aerodynamics are the bigger issue. You could compound curve the front (fairly easy with thick a thick foam buildup), but getting it narrow to match the fiat is best. Maybe a teardrop with tapered sides like GPW's Zephyr PITA in ply but should be possible in foam.

[S. Heisley]

Most of the weight issues seem to depend on the builder. If you use a lot of 2x4 lumber and extra heavy plywood floor, etc, your foamie is not going to be lighter. Please recognize that a 4x8' piece of basic luan plywood that is 1/8" thick weighs about 9 pounds and you can calculate out some of the possible difference from there.

You also can do a little bit of research for yourself here: viewtopic.php?f=2&t=56787&p=1035007#p1035007
(If you are using Google, there should be an icon in the upper right corner of your screen that will allow you to zoom in and read the charts better.)
That I know of, there are 3 foamies listed amongst the 100+ trailers, Aligator (a lift-top half-standy model), Eaglesdare, and GPW's.

Please recognize that weight is not the only consideration for building a foamie. Among the other reasons are the sometimes quick build, lower cost, and, probably most importantly, the lack of plywood delamination worries. Also, because the foam used is thicker than the customary plywood builds, the increased insulation and lessened noise are points to consider.

I had the privilege of seeing atahoekid's foamie up close and it is remarkable. However, I would call his a hybrid because he has a wooden interior, as does KCStudly's. I think MaryC is building a true foamie. (If I forgot anybody, it was not intentional.)

I hope this helps you in making your decisions.

[ghcoe]

I am interested in building a super lightweight tear to pull with my Fiat 500. I want to retain as much MPG as possible while having my own bed. The minimum specs are:

5x8 bed
doors on each side
no kitchen

How light should a well built 5x8 bed foamy be?

My build is based on a Queen size bed, almost. It is 2" shorter than a full queen. I had to give away two inches in storage or bed space. Since I wanted to put a full sized 48 quart cooler in the back I had to sacrifice the bed "room". It is based on a 5x8 platform and could be modified by taking out the bulk head and doing away with the hatch. It has two doors and has shelves in the back for storage, but can be set up for cooking as well. I was shooting for under 500lbs, I think it will come in closer to 400lb.

[working on it]

The most important consideration is the basic trailer weight (frame, axle, wheels, tires, fenders, lighting, coupler, chains, etc...) : i.e. all the equipment common to all types of builds. Upper structure comes later. In my case, the basic trailer weight should've warned me of things to come, but I had a plan, and the 3/4" ply was already bought, and torpedoes be damned, I went with it. The basic trailer weight was exactly 400 lbs.! I was already at 40% of my loaded and ready to camp weight of 1000 lbs. And, armed with Angib's trailer balance spreadsheet, I could see that 1000 lbs was not going to happen. So I fudged my goal, and figured that 25% over was not really too much.... I ended up at 1438 lbs; good luck on your trailer, maybe the foamies have a solution for you!

[rowerwet]

the trailer will be the heaviest part of a foamie, the harbor freight with it's stamped steel is about the lghtest you will find, even aluminum trailers won't come in much lighter and will take a ton of your building funds.
If you look in the design resources at the top of this page you will find a plan for a super lightweight trailer that is a basic "A" frame made of angle iron. For the lightweight build of a foamie this would be fine.
Weight is an issue most noticed when stopping, air resistance will be felt at most highway speeds. Shape is also important, but foam can be shapped in many ways wood never could.
what kind of mileage does a 500 get?

[mezmo]

Hi spd2918,

Here are links for a couple of lightweight builds that may have
useful info for you:

Pico Light Foam and fiberglass
viewtopic.php?f=55&t=50313

"Lite House" Ultralight Monocoque build - 6/25/11 by Thomcat316
viewtopic.php?t=44293
An earlier thread of his:
I'm trying for *reallllly* light..... by Thomcat316
http://tnttt.com/viewtopic.php?f=2&t=42048

Cheers,
Norm/mezmo

[atahoekid]

I had the privilege of seeing atahoekid's foamie up close and it is remarkable. However, I would call his a hybrid because he has a wooden interior, as does KCStudly's. I think MaryC is building a true foamie. (If I forgot anybody, it was not intentional.)

I hope this helps you in making your decisions.

Thanks for the kind words, Sharon. Just as food for thought, that wood interior is just thin (about 1/8" in) underlayment they sell at HD. It's really light and since it's the inside skin of the SIP and not subject to weather, I really didn't care about quality (as an additional bonus, it really finishes up nicely). The sides of my almost 12' long Road Foamie are light enough for me to lift one handed without any real effort. They're built with the inside skin of ply, a 2" panel of foam and an outside skin of fiberglass. Really light, really strong!

[GPW]

...and really Nice !!!

[KCStudly]

My walls (1-1/2 foam, 5 mm marine ply inner, 2x2 cedar wall sill and door frame) with door (1x2 cedar frame, etc.) weighed 45 lbs without the canvas outer skin. 9ft-8in baseline length.

[GPW]

Plywood = 57#/ cu. ft.
Foam 2#/cu.ft. ....