nitromandh

hi everyone. I'm building an air boat out of foam. I tried to build two with wood, but they failed. One of my friends told me about his that he is making out of foam. So i decided to try it. I have the basic shape as u can see in the pics. If anyone has any design modifications they would like to suggest, I'll be open to them. The hull is 36"X20". I have a magnum xl-52 4 stroke with a 11X7 3 blade pusher prop (the prop is not in the pic). I'm not concerned about weight because the foam is so light. I'll try to keep everyone up to date on the build. Please leave a response with tips if you have any.

dadkins

Are you planning on fiberglass over foam ? If so use Epoxy glass not polyester it will eat the foam. Or... I have had relly good luck with HPL laminate - glueing it on with gorilla glue. OR... plywood , veneer, cedar strips.

nitromandh

Actually, I'm on a low cost budget so I'm cheating and covering the whole hull in liquid nails and then sanding it to a smooth finish =P

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No comment.

dadkins

That sounds... very labor intesive. But I wish you the best of luck, are you sure liquid nails won't eat foam -I suppose that is what they use to attach it? duh. does it sand ? last I recall it was pretty rubbery.
Anyways good luck - any kind of a shell on the foam makes it that much more durable.
I have made them using nothing but the high density foam for a little .12 motor.and latex paint covering for a .40 motor.
UNBELIEVABLE acceleration but they do top out fairly quickly in a backflip.

nitromandh

Last time i used it hardened up really well, and I could sand it. So far its working pretty well. I'm waiting for it to dry completely and then I'll let you know how it goes.

nitromandh

Right now the liquid nails is working great. I have about 1 hour of sanding into with a circular sander and 80 grit sand paper. I've go the sides done, and most of the bottom. I'll try to have pictures up soon.

dadkins

NICE ! cant wait to see it.

nitromandh

I've got a few spots to fill in because of the sander, but I'll try to get pics when I'm finished covering it.

nitromandh

Ok, I've finally got a pic. The bottom is really smooth accept for the front. I still have to finish sanding that, and the sides. It's coming along great!!!!
By the way. Does anyone know of a spray paint that does not eat through foam? I would greatly appreciate it!!!

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No comment.

nitromandh

Alright. Thanks!!!

nitromandh

Alright. Thanks!!!

dadkins

Looouuuking Goooud ! I am impressed.
Is there any foam showing on the bottom? or are you talking about paint for the top. I have used latex with decent results

dadkins

Latex paint - Ok I admit it doesnt look nearly as nice as some of the boats on RCU but I tend to be really hard on my toys and their lifespan is usually limited to about a year of summer /winter thrashings.

nitromandh

Thanks for pics. They look really cool compared to my other builds that were a fail. I think I'll go all out and make it look good. I was searching through my garage and found a can a spray paint that doesn't eat the foam!!!! I'll spray it and get pics up when I'm done.

nitromandh

I got it painted with 3 coats. Its a pretty nice blue. I'm happy with how well its coming along.

nitromandh

Does anyone have a picture of a nice dual rudder set up? I don't want it to be attached to the motor mount. If someone could give me some ideas that would help a lot. Thanks

dadkins

This was a dual rudder set up independent of the motor mount - at one time I had 4 rudders on the mighty duck. Two huge ones outside the prop blast and two little ones in it. handled awesome.

nitromandh

When I'm designing the engine mount, should I position the gas tank below the engine or at engine level? I'm not sure if the motor can pull the fuel up, so can anyone give me advice?

dadkins

I have had best luck with a platform right behind the motor at the same level or even slightly higher than the carb.

nitromandh

How big should i make the air rudders? I have 22 guage steel and I'm not sure how big to make them

dadkins

For twin rudders and a .52 4 stroke I would probably shoot for about 20-25 sq in. ea 3" x 7" or 4" x 6" - but... I would make them out of almost anything but steel. you dont want that weight up high like that.

nitromandh

Do you have any ideas what i should make them out of?

dadkins

I prefer Flexible plastics stiff enough not to deflect in the WIND. or plexiglass, wood, plywood, sintra, coroplast.