What is the cheapest foam sheeting that one can buy that will not
melt when you apply polyester resin to it? What is the best source for
this foam? How much does it cost? Would it better than using luan as a
core?

I need a bigger jon boat. Mine is 40 years old and starting to fall
apart. I am going to build one, but money is a deciding factor in
this. If I had the cash, I would just go to Outdoor World and buy one
of theirs for $500. But since I don't have that kind of green I guess
I can build one. I would like to use foam as a core because it is
light and easy to form. I could see glueing a boat together out of 1/2
or 3/4 inch sheet foam and then glassing it. It just feels like it
would be easier than building a frame and then attaching the luan and
then glassing that. However I have never built a boat. I have rebuilt
a couple, but never built one from scratch.

Any advice? Pointers? Suggestions?

Do a google search for "stitch and glue".
"Ookie Wonderslug" wrote in message
...
What is the cheapest foam sheeting that one can buy that will not
melt when you apply polyester resin to it? What is the best source for
this foam? How much does it cost? Would it better than using luan as a
core?

I need a bigger jon boat. Mine is 40 years old and starting to fall
apart. I am going to build one, but money is a deciding factor in
this. If I had the cash, I would just go to Outdoor World and buy one
of theirs for $500. But since I don't have that kind of green I guess
I can build one. I would like to use foam as a core because it is
light and easy to form. I could see glueing a boat together out of 1/2
or 3/4 inch sheet foam and then glassing it. It just feels like it
would be easier than building a frame and then attaching the luan and
then glassing that. However I have never built a boat. I have rebuilt
a couple, but never built one from scratch.

Any advice? Pointers? Suggestions?

Plywood would be cheaper, lighter, and easier to build.
Like the fellow wrote "stitch and glue", also called "stitch and tape".
A cheaper building method is chine batten construction which uses strips
of wood along the seams instead of resin putty.

The foam boatbuilding I've seen described requires a building frame to which
a special boatbuilder's foam is attached. It's then covered on the outside
with lots of fibreglass for strength. Then it's femoved from the bulding
frame, turned over, and covered on the inside with more fibreglass. All
that fibreglass makes it heavy.
--
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William R. Watt wrote:
Plywood would be cheaper, lighter, and easier to build.
Like the fellow wrote "stitch and glue", also called "stitch and tape".
A cheaper building method is chine batten construction which uses strips
of wood along the seams instead of resin putty.

The foam boatbuilding I've seen described requires a building frame to which
a special boatbuilder's foam is attached. It's then covered on the outside
with lots of fibreglass for strength. Then it's femoved from the bulding
frame, turned over, and covered on the inside with more fibreglass. All
that fibreglass makes it heavy.

And the cost of the resin in that glass makes it expensive

--
I am building a Dudley Dix, Argie 10 for my daughter. Check it out:
http://home.comcast.net/~jonsailr

William R. Watt wrote:
The foam boatbuilding I've seen described requires a building frame to which
a special boatbuilder's foam is attached. It's then covered on the outside
with lots of fibreglass for strength. Then it's femoved from the bulding
frame, turned over, and covered on the inside with more fibreglass. All
that fibreglass makes it heavy.

That's an odd thing to say. Fiberglass/foam core or sandwich
construction is usually described as very light & strong.

However, it's not cheap. The cheapest type of foam insulation is not
suitable for core material as it does not have a good bonding surface
and it's shear strength is comparable to lumpy oatmeal.

Luan underlayment is probably the cheapest per square foot for boat
building material that has a chance of success. It will probably have
durability & longevity issues unless it's given very careful work during
building & good maintenance during use.

Here's a thought- has anybody tried building a stitch-n-glue boat out of
OSB?

Fresh Breezes- Doug King

William R. Watt wrote:

The foam boatbuilding I've seen described requires a building frame to
which
a special boatbuilder's foam is attached.

That's one way, probably the easiest.

It's then covered on the
outside
with lots of fibreglass for strength. Then it's femoved from the bulding
frame, turned over, and covered on the inside with more fibreglass. All
that fibreglass makes it heavy.

What absolute BULL ****.


Lew

Lew Hodgett wrote:

William R. Watt wrote:

The foam boatbuilding I've seen described requires a building frame
to which
a special boatbuilder's foam is attached.


That's one way, probably the easiest.

It's then covered on the outside
with lots of fibreglass for strength. Then it's femoved from the bulding
frame, turned over, and covered on the inside with more fibreglass. All
that fibreglass makes it heavy.


What absolute BULL ****.


Lew

Don't hold back, Lew.
As a data point on the weight of foam sandwich construction, my current
project is a 29' sailing trimaran built in core-cell foam, knitted glass
and epoxy. The main hull, with interior, tanks and some fancy cockpit
joinery weighs about 900 lbs.

On Wed, 05 Jan 2005 03:43:20 GMT, Ookie Wonderslug
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

What is the cheapest foam sheeting that one can buy that will not
melt when you apply polyester resin to it?

urethane. see below

What is the best source for
this foam?

hardware stores. glass shops

How much does it cost? Would it better than using luan as a
core?

No.!!!!!

First, unless you _want_ to build a boat (a desire will not argue
with) look at secondhand stuff, pro built. You will probably not pay
more than building, and should you be one of those fortunate souls
that can sell stuff you have, you will get more for it.

OK. Wood cores vs foam cores.

(1) For a small knockabout, use ply core. It spreads (resists point
loads; rocks, feet, jetties, etc) the load far more than any foam. If
the skin is damaged, it still keeps some shape. Kayaks are built from
ply or strip wood, because the result is more bump resistant/kg than
foam/glass. The wood actually has a structural part to play. For
larger boats it's different. They need stiffness and are less likely
to encounter point loads. Even there, there have been arguments.

(2) I mentioned urethane. Avoid that crap. It crumbles unbder stress.
The ONLY foam worth using in boats is expensive PVC foam. For cost
check out Airex/Klegecell. (Am I showing my age?) For a normal use,
biggish boat, you can't beat it. For a boat that is light and tough,
for rowing and knocking about (less than 20') use ply/glass.

The only _possible_ advantage for foam is that it will not rot. But a
fracture of the glass skin can cause major problems anyway. So....

(3) Boats on a budget are always a problem. Boating above all others
brings out the "weep once" feature.

Foam compatible with resin will cost much much more than plywood.
We sell the foam and the plywood and everything else. We often say that
in small sizes, a foam sandwich boat will cost twice what a stitch and
glue boat cost.
Jacques from bateau.com

Old Nick wrote:
On Wed, 05 Jan 2005 03:43:20 GMT, Ookie Wonderslug

vaguely proposed a theory
......and in reply I say!:

remove ns from my header address to reply via email

What is the cheapest foam sheeting that one can buy that will not
melt when you apply polyester resin to it?

urethane. see below

What is the best source for
this foam?

hardware stores. glass shops

How much does it cost? Would it better than using luan as a
core?

No.!!!!!

First, unless you _want_ to build a boat (a desire will not argue
with) look at secondhand stuff, pro built. You will probably not pay
more than building, and should you be one of those fortunate souls
that can sell stuff you have, you will get more for it.

OK. Wood cores vs foam cores.

(1) For a small knockabout, use ply core. It spreads (resists point
loads; rocks, feet, jetties, etc) the load far more than any foam. If
the skin is damaged, it still keeps some shape. Kayaks are built from
ply or strip wood, because the result is more bump resistant/kg than
foam/glass. The wood actually has a structural part to play. For
larger boats it's different. They need stiffness and are less likely
to encounter point loads. Even there, there have been arguments.

(2) I mentioned urethane. Avoid that crap. It crumbles unbder stress.
The ONLY foam worth using in boats is expensive PVC foam. For cost
check out Airex/Klegecell. (Am I showing my age?) For a normal use,
biggish boat, you can't beat it. For a boat that is light and tough,
for rowing and knocking about (less than 20') use ply/glass.

The only _possible_ advantage for foam is that it will not rot. But a
fracture of the glass skin can cause major problems anyway. So....

(3) Boats on a budget are always a problem. Boating above all others
brings out the "weep once" feature.

Ookie Wonderslug wrote:

What is the cheapest foam sheeting that one can buy that will not
melt when you apply polyester resin to it? What is the best source for
this foam? How much does it cost? Would it better than using luan as a
core?

I need a bigger jon boat. Mine is 40 years old and starting to fall
apart. I am going to build one, but money is a deciding factor in
this. If I had the cash, I would just go to Outdoor World and buy one
of theirs for $500. But since I don't have that kind of green I guess
I can build one. I would like to use foam as a core because it is
light and easy to form. I could see glueing a boat together out of 1/2
or 3/4 inch sheet foam and then glassing it. It just feels like it
would be easier than building a frame and then attaching the luan and
then glassing that. However I have never built a boat. I have rebuilt
a couple, but never built one from scratch.

Any advice? Pointers? Suggestions?


Lauan is generally not water resistant. It'll fall apart very quickly.
No part of a boat should be made of it.
The foams that have any structural properties and expensive, and the
cheap foams are weak.
The best material for building a small boat inexpensively is exterior
fir AC plywood and stitch & glue construction. A light sheathing of
glass in epoxy will stop the fir from checking.