Hi Brian,

I wish there was a standard way to draw diagrams on the net. I'm not
quite sure if I've understood correctly. Do you mean that the first set
of ribs would be mainly vertical (for a "conventional bathtub", they
would look like U's), and the second set would be longitudinal? ie, a
see-through grid of ribs. If so, would you recommend attaching a
sheathing of thin ply before applying the glass skin?

Also, by 2 inches, do you mean the width of the ply strips?

Sorry if I'm missing the obvious, I haven't yet learned much about boat
building, and probably don't see some of the things that are clear to
others.

wrote in message
ups.com...
Hi Brian,

I wish there was a standard way to draw diagrams on the net. I'm not
quite sure if I've understood correctly. Do you mean that the first set
of ribs would be mainly vertical (for a "conventional bathtub", they
would look like U's), and the second set would be longitudinal? ie, a
see-through grid of ribs. If so, would you recommend attaching a
sheathing of thin ply before applying the glass skin?

See http://www.gartsideboats.com/jessie.php
This is a could moulded design, where temporary stringers are laid fore and
aft, to hold steam bent frames. This is covered with two layers of wood, one
1/4" thick, the second 1/8". When you add a 3rd layer, you can probably
leave the frames out. BTW, this boat is not covered with glass.
If you build the same boat with strips, you need glass inside and out but no
ribs are needed.

Meindert

See http://www.gartsideboats.com/jessie.php
This is a could moulded design, where temporary stringers are laid fore and
aft, to hold steam bent frames. This is covered with two layers of wood, one
1/4" thick, the second 1/8".

When you add a 3rd layer, you can probably
leave the frames out.

Leaving the frames out would be good - otherwise I'd have to put a
layer of wood on the inside too (for comfort reasons - it is a hot
tub).

BTW, this boat is not covered with glass.
If you build the same boat with strips, you need glass inside and out but no
ribs are needed.

I think sheathed strip would be the easiest construction method, if I
could get it to work for the desired curvature. Could I use very thin
wood strips (1/8" or so), and rely almost entirely on the fiberglass
for strength? Basically the only purpose of the wood would be to avoid
making a mold (as would be needed for 100% fiberglass construction).

Meindert

Thanks again

wrote in message
ups.com...
Leaving the frames out would be good - otherwise I'd have to put a
layer of wood on the inside too (for comfort reasons - it is a hot
tub).

Don't know if anyone has mention this before, but as I understand epoxies
are highly sensitive to temperature. This was googled out on "epoxy
temperature" search:
http://www.epoxyproducts.com/novolac.html

I anticipate the tub being about 104 degrees F. So notwithstanding any
problems with my heat source, I should be below the 140-160 degree
maximum (for wet conditions) of regular epoxy. Although my heat source
is wood-fired, I have a thermostat of sorts worked out. I can probably
control the temperature to within a few degrees.

On 19 Oct 2005 13:45:10 -0700, wrote:

Hi Brian,

I wish there was a standard way to draw diagrams on the net. I'm not
quite sure if I've understood correctly. Do you mean that the first set
of ribs would be mainly vertical (for a "conventional bathtub", they
would look like U's), and the second set would be longitudinal? ie, a
see-through grid of ribs. If so, would you recommend attaching a
sheathing of thin ply before applying the glass skin?

Also, by 2 inches, do you mean the width of the ply strips?

Sorry if I'm missing the obvious, I haven't yet learned much about boat
building, and probably don't see some of the things that are clear to
others.


This is a speculative idea, rather than the fruit of long experience.
Yes I am thinking of ply ribs in two directions at right angles,
Whose faces are all vertical, so that in plan view, they would look
a noughts n crosses game of lines say 1/4 in thick, and in side view
they would be 2 inches deep and wide (at the sides.)
An internal and external skin would then provide a strong stiff light
structure. The crucial detail is making the inside skin fair and
smooth. This is left as an exercise for.... :-)

Brian Whatcott

Brian Whatcott wrote:

This is a speculative idea, rather than the fruit of long experience.
Yes I am thinking of ply ribs in two directions at right angles,
Whose faces are all vertical, so that in plan view, they would look
a noughts n crosses game of lines say 1/4 in thick, and in side view
they would be 2 inches deep and wide (at the sides.)
An internal and external skin would then provide a strong stiff light
structure. The crucial detail is making the inside skin fair and
smooth. This is left as an exercise for.... :-)

Brian Whatcott

Interesting idea. For the inner/outer skins, did you have in mind
multiple layer of wood like the boat Meindert Sprang pointed out, or
fiberglass, or both?

I wonder also if it would be wise to put a coat of epoxy on the inner
ribs, to prevent rot (just in case steam managed to work through the
outer skin somehow). Perhaps regular wood sealer could even be used
instead of epoxy, since its adhesive properties aren't needed, only a
moisture barrier.

On 23 Oct 2005 14:26:33 -0700, wrote:

Brian Whatcott wrote:

This is a speculative idea, rather than the fruit of long experience.
Yes I am thinking of ply ribs in two directions at right angles,
Whose faces are all vertical, so that in plan view, they would look
a noughts n crosses game of lines say 1/4 in thick, and in side view
they would be 2 inches deep and wide (at the sides.)
An internal and external skin would then provide a strong stiff light
structure. The crucial detail is making the inside skin fair and
smooth. This is left as an exercise for.... :-)

Brian Whatcott

Interesting idea. For the inner/outer skins, did you have in mind
multiple layer of wood like the boat Meindert Sprang pointed out, or
fiberglass, or both?

I wonder also if it would be wise to put a coat of epoxy on the inner
ribs, to prevent rot (just in case steam managed to work through the
outer skin somehow). Perhaps regular wood sealer could even be used
instead of epoxy, since its adhesive properties aren't needed, only a
moisture barrier.

I thought, fix thin laths to the inner rib contours. The laths need
not be gapless. Then a layer of glass on top.

Brian W