foam

[gub...@my-deja.com]

Can I use Isofoam to built UH10f?

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Before you buy.

[Calaairy]

I'm not aquainted with the name isofoam, but I would conjecture your not
refering to the blue or pink 1" to 2" x 4'x8' sheets of the 2lb per Cu ft
polystyrene etc. Any foam having an extreme open cell structure is not
suitable for hovercraft as any pinhole will allow water penetration and become
heavier over time (The Scat 1 encapsulated boyancy foam is an example) The
blue or pink polystyrene foam (if I named it right) absorbs some water also but
at a greatly reduced rate because of its density and the usual practice in
using this foam in hovercraft is to fiberglass only one side such as the top
and leave the bottom open to the air. Any moisture absorbtion will evaporate
and the craft will allways be light. This is the same foam used for docks and
is very water resistant.
This foam has great potential when glued with foam-in-a-can(water mist cures
it) and epoxy.
I wouldn't go less than 2lb per CF on a UH-10F as the design needs all the
rigidity the foam can give it as built to the plans.

[MW]

My intent was to use closed cell polystyrene(like coffee cups) foam and
epoxy resin and fiber glass encapsulate it.

From my previous boating experiences, I don't think that it would be a
problem.

Let me know what you think.

Calaairy <cala...@aol.com> wrote in message
news:20000116105936...@ng-bk1.aol.com...

[Gordon McAndrew]

"MW" <mic...@freewwweb.com> wrote:

;>My intent was to use closed cell polystyrene(like coffee cups) foam and

;>epoxy resin and fiber glass encapsulate it.
;>
;>From my previous boating experiences, I don't think that it would be a
;>problem.
;>
;>Let me know what you think.
;>
;>Calaairy <cala...@aol.com> wrote in message
;>news:20000116105936...@ng-bk1.aol.com...
;>> I'm not aquainted with the name isofoam, but I would conjecture your not
;>> refering to the blue or pink 1" to 2" x 4'x8' sheets of the 2lb per Cu ft
;>> polystyrene etc.

I think you should stay away from the white styrofoam and stay with the pink
or blue extruded polystyrene that you can get at lumber yards. The white
stuff (that coffee cups) are made of has much lower strength properties and I
believe I remember it also absorbs more water.

[ke...@peesee.at.home]

>My intent was to use closed cell polystyrene(like coffee cups) foam and
>epoxy resin and fiber glass encapsulate it.

sorry to say it, but white foam is not closed cell. it's open cell.

just because it holds coffee long enough to drink it doesn't mean it won't
absorb water.

that said, i've talked to people who used white foam in their crafts with decent
results. it depends on your intended use and construction techniques.

i'm just relaying a point of view, which i'm currently undecided on but which i
think makes sense. no flames, please, unless you just wanted to hit me 'cause
it's me talking:

the idea is that, if you go out on water for a few hours and then park your
craft on land for a week or a month, your water exposure is limited.

the people in question claimed to have built a craft of white foam, with pink or
blue on the bottom. there was, supposedly, no fiberglass or wood or anything on
the bottom, other than skids. i did not check under the craft to verify this.

they had wood and glass on the top, and on the sides.

the reasoning is that the craft will absorb water while out there, but during
the much longer time of being parked it will dry out again. the key is that
there is no barrier to prevent the water from leaving the foam.

i'm not making any discussion about how much of your foam you'd leave on the
riverbanks, rocks, and trees along the way. i'm not sure if i'd do this for a
craft that i personally would drive, because the ratio of holes and trips is
still quite high for me.

come to think of it, though, a bit of spray foam would fix all damage. and
you'd have to admit it would be extremely light.

this craft was made for river cruising, not racing or chasing dogs or anything
exciting.

[kjue...@my-deja.com]

In article <slrn887ja...@peesee.at.home>,

--
I see it from another point of view:
Styrofoam (white) and Polystyrene (blue or pink) are not very good in
heat. They also are not 100% water tight so why should I spend a few
hundred hours of my time, $3000 in total and save $200? This is what
Polyurethane foam in 2lb density will cost more for a typical craft.
The blue/pink foam is good for stuff like rudders, ducts/guards and
interior things where you want to hotwire it and where it will never be
IN the water.

Juergen
http://www.crosswinds.net/~kjs/index.html

[Gordon McAndrew]

kjue...@my-deja.com wrote:

;>I see it from another point of view:

;>Styrofoam (white) and Polystyrene (blue or pink) are not very good in
;>heat. They also are not 100% water tight so why should I spend a few
;>hundred hours of my time, $3000 in total and save $200? This is what
;>Polyurethane foam in 2lb density will cost more for a typical craft.
;>The blue/pink foam is good for stuff like rudders, ducts/guards and
;>interior things where you want to hotwire it and where it will never be
;>IN the water.

I looked on a manufacturer's site about the characteristics of blue
polystyrene and it showed that the water absorption of the foam was .07% by
volume.

With that little absorption I am not going to worry about it much.

[ke...@peesee.at.home]

these sentiments are both perfectly valid, and you'll get support for each of
them on this list, if my memory of past discussions is accurate. in fact, i'm
not sure exactly which school i'd subscribe to until i actually get a garage.

one thing to consider is that a first project could be built with white or pink
foam primarily, and a later project, when you know what you're doing, could be
made with a higher quality foam or some other substance altogether.