On Sat, 29 May 2004 22:43:44 UTC, Jim Conlin
wrote:

What weight of glass is used? I've found taht its very hard to get glass over
8-10 oz. not to be cloudy.

Why go higher than 4 or 6?? I got multilayers 6oz on my kayak (hull).

Regards
--
steen - menzi.dk
Ready for OpenOffice?
---

"Chalatso" ) writes:
Graduating to my first multi-sheet stitch-n-glue... butt joints with blocks
are ugly, scarfing will throw off my sheet layout. Can I use a plain butt
joint, supported on both sides by glass and epoxy?

yes. however I don't find butt blocks ugly. the ones on my Dogskiff are
beautiful, traditional, functional, and cheap. edges tapered with a sander
before installation. traditional clinched copper nails. lauan underlayment
plywood. a thin line of epoxy applied to the exterior seam with a
toothpick to keep moisture out of the join. interior finished clear with
cheap linseed oil. photos on my website under "Boats".

--
------------------------------------------------------------------------------
William R Watt National Capital FreeNet Ottawa's free community network
homepage: www.ncf.ca/~ag384/top.htm
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I have used a joint that Dynamite Payson developed. It calls for making a
butt joint by scarfing both sides of the stock and using epoxy/glass for the
joint. Lay the pieces on a flat surface in position. Mark the length of
the scarf on both ends. Grind half way through both pieces where they meet
and tapering to nothing at the ends of the scarfs. This results in a
shallow vee spanning both pieces. Fill the vee with glass cloth, roving and
epoxy. When set, grind the epoxy surface flat. Now, carefully turn the
assembly over and make another vee just like before. Fill vee as on the
other side. This makes a very strong joint and if done carefully is not
detectable (if painted). Email me if the method is not clear.
Dave
"Chalatso" wrote in message
. ..
Graduating to my first multi-sheet stitch-n-glue... butt joints with
blocks
are ugly, scarfing will throw off my sheet layout. Can I use a plain butt
joint, supported on both sides by glass and epoxy?

Chuck

"Dave W" wrote in message ...
I have used a joint that Dynamite Payson developed. It calls for making a
butt joint by scarfing both sides of the stock and using epoxy/glass for the
joint. Lay the pieces on a flat surface in position. Mark the length of
the scarf on both ends. Grind half way through both pieces where they meet
and tapering to nothing at the ends of the scarfs.

You don't have to taper it down that far. I just take the pieces
temporarily end to end and belt sand down about 30% of the way through
the pieces (6mm-1/4" material) making a slight trough about 4-5" wide,
lay in a couple of layers of fiberglass tape, say 6 oz, fill with
resin, and cover it with a sheet of wax paper to cure, flip and repeat
on the other side of the board. (note: it is easier to wet the
fiberglass material before laying it on the part, soak the part good
first too. Remember, it is easier to draw goo up through cloth, than
drive goo down into air under cloth I have even used a couple of
layers of 3.5oz tight weave right on the outside of the wood, both
sides, putty in the edges, paint. Although the joint you make has a
"bulge", it will also tend not to bend there. So when you bend the
part around the frames, the flatspot has a nice "bulge" to fair right
in and paint over... Hope that makes sence, it is the easiest of all
but should not be done without the advice of the designer.
Scotty


This results in a
shallow vee spanning both pieces. Fill the vee with glass cloth, roving and
epoxy. When set, grind the epoxy surface flat. Now, carefully turn the
assembly over and make another vee just like before. Fill vee as on the
other side. This makes a very strong joint and if done carefully is not
detectable (if painted). Email me if the method is not clear.
Dave
"Chalatso" wrote in message
. ..
Graduating to my first multi-sheet stitch-n-glue... butt joints with
blocks
are ugly, scarfing will throw off my sheet layout. Can I use a plain butt
joint, supported on both sides by glass and epoxy?

Chuck

Just a thought,
I thought of building a canoe out of 2 layers of 1/8 ply, The joints could
them be staggered there would be no transition, no complicated scarfs and
more strength than butt joints, I was thinking of using contact cement
between the layers, only because I dont have a vacuum to hold the layers at
a uniform tension.
Another idea I am playing with is making two 8' halves with transoms at the
end and joining them together as a single canoe.
Hope this helps

"John R Weiss" wrote in message
news:7t9uc.10769$IB.9176@attbi_s04...
"Chalatso" wrote...
Well, the boat is the bateau.com "cheap canoe," and they suggest a butt
joint, with a block glued over the butt. I think the method suffers a
lot
for looks. The joint is right across the fattest part of the canoe,
exactly
at the middle. There's added stiffness in the sides from a rubrail, and
I
might add a little inwale and a bottom runner, if the taped butt makes
me
nervous.

You might be able to make it a bit more elegant by tapering the block
edges.
From the photo of the NC16 on the site, the thwart will draw a lot of
attention away from the blocks. Also, I note they say the blocks may be
made from fiberglass, so a thin strip of tape, followed by a couple layers
of cloth built up with feathered edges may work out just fine.

From the curve of the hull, it appears the tensile stress on the outside
of
the hull (where they show no blocks) will predominate over the compressive
stress inboard. Also, if the thwart is glassed in, it will help
considerably in stabilizing the joint. You might also add a fillet or
block
under the edge of the thwart, if not already in the plans.

If you're going to paint it, using Kevlar instead of glass may provide
more
stiffness with less build-up...

You can do that. If building on a set of molds, just lay out the first
layer so that the ends of the pieces land on a mold. You can stitch the
wood to the mold or to the other pieces of wood and then use a syringe to
'tack weld' along the edges with epoxy. Pygmy Kayaks are built this way.

Brian

--
http://www.advantagecomposites.com/tongass -- My 22' Tolman Skiff project
http://www.advantagecomposites.com/catalog -- Discounted System Three
Resins products


..
"C" wrote in message
news:%gJwc.687269$Ig.205733@pd7tw2no...
Just a thought,
I thought of building a canoe out of 2 layers of 1/8 ply, The joints could
them be staggered there would be no transition, no complicated scarfs and
more strength than butt joints, I was thinking of using contact cement
between the layers, only because I dont have a vacuum to hold the layers
at
a uniform tension.
Another idea I am playing with is making two 8' halves with transoms at
the
end and joining them together as a single canoe.
Hope this helps

"John R Weiss" wrote in message
news:7t9uc.10769$IB.9176@attbi_s04...
"Chalatso" wrote...
Well, the boat is the bateau.com "cheap canoe," and they suggest a
butt
joint, with a block glued over the butt. I think the method suffers a
lot
for looks. The joint is right across the fattest part of the canoe,
exactly
at the middle. There's added stiffness in the sides from a rubrail,
and
I
might add a little inwale and a bottom runner, if the taped butt makes
me
nervous.

You might be able to make it a bit more elegant by tapering the block
edges.
From the photo of the NC16 on the site, the thwart will draw a lot of
attention away from the blocks. Also, I note they say the blocks may be
made from fiberglass, so a thin strip of tape, followed by a couple
layers
of cloth built up with feathered edges may work out just fine.

From the curve of the hull, it appears the tensile stress on the outside
of
the hull (where they show no blocks) will predominate over the
compressive
stress inboard. Also, if the thwart is glassed in, it will help
considerably in stabilizing the joint. You might also add a fillet or
block
under the edge of the thwart, if not already in the plans.

If you're going to paint it, using Kevlar instead of glass may provide
more
stiffness with less build-up...

"Chalatso" wrote in message ...
Graduating to my first multi-sheet stitch-n-glue... butt joints with blocks
are ugly, scarfing will throw off my sheet layout. Can I use a plain butt
joint, supported on both sides by glass and epoxy?

Chuck

I am the designer of that boat.
Use the butt blocks please.
Do not assume that they are ugly: we work hard on locating the butt
blocks in a strategic spot. Here, the bottom butt block is under the
seat, you can't see it.
The side butt block is right in the middle and looks very appropriate
there. It is a local reinforcement.
Look at the pictures he
http://www.bateau2.com/gallery/NC16/index.htm

Those butt blocks aren;t bad at all.

If you scarf instead of using butt blocks, you will need 2 mores
sheets of plywood because of the width of the scarf . . .

There is another version of that plan that uses fiberglass splices and
produces a longer boat but no scarf version.

About fiberglass splices.
Payson and Carnell miss an important point. They use plain woven glass
in which half of the fibers run paralell to the seam: a complete waste
of glass and resin.
The proper way to build such a seam is with biaxial 45/45. With that
type of glass, all the fibers work and it also adds a little torsional
strength.
I don't know why that point is not understood. I mentioned it for the
1st time here 12 years ago and designers still specify the wrong type
of glass for splices and stitch and glue seams.

Jacques from bateau.com

Jacques,
THANK YOU !!

Not for this particular boat/thread, but just in general for this specific
snippet of info . . .

It 'looked good on paper' and a LOT of 'the experts' recommended it.
However, for some reason I always had a feeling in the 'back of my mind'
{from my Textile Engineering Degree ?? An article I had read ??} that
something didn't quite fit.

Regards,
Ron Magen
Backyard Boatshop

"Jacques" wrote ...
About fiberglass splices. . . .{snip} . . .The proper way to build such a
seam is with biaxial 45/45. {snip}, all the fibers work and it also adds a
little torsional strength.

(Jacques) wrote in message om...
About fiberglass splices.
Payson and Carnell miss an important point. They use plain woven glass
in which half of the fibers run paralell to the seam: a complete waste
of glass and resin.
The proper way to build such a seam is with biaxial 45/45. With that
type of glass, all the fibers work and it also adds a little torsional
strength.
I don't know why that point is not understood. I mentioned it for the
1st time here 12 years ago and designers still specify the wrong type
of glass for splices and stitch and glue seams.

Jacques from bateau.com

With all respect and understanding of your considerable advantage in
experience and education, I question.
I think that they missed no point, as if done as reccomended, most of
these joints and seams have at least two layers of cloth on either
side creating an area that is much stronger than the material it holds
to. If designed and built correctly I think the cloth is actually
overkill, so the biax may even be more overkill. Granted, your theory
is spot on as to the strengh of the two in lamination but I don't
think it is necessary in standard construction in smaller "typically
engineered" stitch and tape boats.
Now, I have seen plans out there that only use one layer or even none
with epoxy, I consider those inferior and somewhat lazy...
Scotty, who will consider telling you who I am after Jaques makes me
look like a noobie..