pontoon or hull for small seaplanes

[scottperkinsusa]

I have a very small single seater airplane and I am thinking about creating
a hull to drop it into or an enclosed pontoon to set it on top of.

In either case I would say what I need is to build a boat hull thus why I am
here. My nephew is engineering student and is going to use/study
acquire a product called IRON-CAD as student version which is supposed
to be a super easy to use 3D cad program... alledged to be the
user friendliest of any ever available. ( 3 or 4 thousand dollars for
commercial versions )

The only thing I can see different is that an seaplane hull requires
a step about midway along the length of the hull. Since the
Free Delft program is thought of so highly, I was wondering
if people would recommend that I play with it before I try the
IRON-CAD program. I expect to build the hull out of a foam sandwich
composite... probably some kind of foam boards covered both sides
with fiberglass. So that rules out any 3D curves if that is what you
call them. The same design requirements I would think as if building
with plywood.

I think I played with Carlsons design program 4 or 5 years ago and
was marginally productive with creating basic concepts but I couldnt
see how I could complete a project with it.

All suggestions appreciated.
Thanks
Scott

[USCGRET/E8]

Are you doing this so as to land/takeoff on the water?

[USCGRET/E8]

...if so, you may want to consider something like this: http://www.keywestfloats.com/

[alan white]

It may be that seaplane floats are commonly designed and built by owners. I don't know. I have only seen aluminum floats, but I'm sure there must be composite floats out there.
One strong advantage of aluminum has to do with its tensile strength not being lost completely when crushed, while composites are more egg-like and while extremely resistant to deformation, if deformed enough, they lose all strength and integrity in the effected area.
Materials used in boat hulls are subject to different stresses and suffer different penalties for material failures.

Alan

[scottperkinsusa]

yes of course I want to take off from and land on water...
attached are a few concept photos I have gathered. I have many more.
I am Familiar with the Keywest Floats mentioned... That float
is solid white bead styrofoam that has been carved to shape
and covered with layer of fiberglass cloth. I would think
it heavier than it needs to be but it sure cannot fill up with
water and with a sandwich of that thickness it sure has
to be strong ....at least till the bottom gets wiped off on
a sharp rock etc.

[kach22i]

I used to read the magazine Kit Plane years ago. Full Lotus floats got a lot of good press back then.

Link (inflatable):
http://www.full-lotus.com/index_main.html

[scottperkinsusa]

Lotus floats are three times as heavy as a set of aluminum floats.
They do have their advantages in shock absorbtion like air filled
tires, but they are incredibly heavy.

Aluminum is seen generally as lighter than composites unless
super hi dollar carbon and molds are used.

Any suggestions as to software for modeling the flat panels
used to make my hull or floats ?

[eponodyne]

I'm willing to bet that this is what you're looking for.

What sort of plane do you fly?

[USCGRET/E8]

yes of course I want to take off from and land on water...

Sorry, I wasn't sure...I thought you might be building a boat like mine...

[USCGRET/E8]

That float
is solid white bead styrofoam that has been carved to shape
and covered with layer of fiberglass cloth. I would think
it heavier than it needs to be but it sure cannot fill up with
water and with a sandwich of that thickness it sure has
to be strong ....at least till the bottom gets wiped off on
a sharp rock etc.

I once had a little 12' sailboat made like that, except it was covered with abs plastic. It was extremely tough and not all that heavy. What would be your target weight for the entire conversion?

[kach22i]

White bead board soaks up water (expanded polystyreen).

The blue and pink rigid insulation (extruded polystyreen) does not soak up water (very very very little).

USCGRET/E8, I like the bat-boat.

[USCGRET/E8]

I think they used to call the good foam "Closed Cellular"?

[kach22i]

Originally Posted by USCGRET/E8

I think they used to call the good foam "Closed Cellular"?

Yes, the white stuff is "open cell".

The blue and pink board is "closed cell".

They make hovercraft ducts out of the white board because it bends, the body and anything near the waterline is glass covered blue/pink board. They hot-wire cut the blue and pink just as they do the white board. I would think building an airplane float would be similar.

[USCGRET/E8]

Well Scott, what have you come up with so far...?