(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


I would ammend my question with the note that I was speaking, as was
the origional poster, to small, non planing, people powered hulls.
Scotty, knows his spelling and punctuation are outrageous.

Small point of information: The original poster was thinking of not using
plywood butted end to end with any kind of joint ...scarf or butt or what
have you. He was thinking more along the lines of a cold-molded approach
where the panels were build from 2 layers of 1/8" skin, staggering the
joints as he went. I can't see how your boat would benefit over this by
using butt block joints, from a strength perspective that is. If I am
wrong, please correct me.

Personally, I am completely happy with butt blocks and don't mind how they
look, especially in a small lighter weight boat or when splicing thin
plywood. They can be a real time saver during construction and are fine for
strength. In larger boats, they can be a PITA if on the decking or anywhere
near the fairbody inside the hull because they tend to disrupt the normal
flow of water and it creates a wet dirty area that's hard to keep clean and
dry ...this is Oregon, not Florida, so things often remain wet and dirty if
not designed for easy drainability.

Brian

PS: In the link below for my current project, you will note that I deviated
from the designer's original plan on the side panels. Because of
order-of-construction versus shop size constraints and the pain level
associated with outdoor structures around here, I chose to build the 24'
side panels out of a forward 16' scarfed section and then used a butt block
to join in the last 8' in the aft section. The designer uses all scarfs.
But in this case, the forward scarf allowed a natural bend in a critical
area, while using a built-in-place butt block for the aft section allowed me
to use panel sections that fit in my cramped shop and were easier to install
in-place than scarfed joints would have been. The butt block is in a
straight section of the hull so there is no issue about curvature and
changing stiffnessnes. Although the designer prefers scarfs, he approved my
butt block approach prior to my using it. Decking and bottom panels are all
scarfed, but are also all short enough to be built in my shop. No drainage
issues will exist.

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


..
"Jacques" wrote in message
om...
"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.

Right on. In addition, the 45/45 biax is built from 2 layers of
unidirectional glass. This is stronger than a normal weave where the yarn
passes over and under other yarn throughout the material ...this naturally
puts a cutting force across the yarn and consequently unidirectional layers
in biax (etc) can take more tension before failing.

Brian D

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


..
"Jacques" wrote in message
m...
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

(Backyard Renegade) wrote

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.

We are each correct in the sense that the weaker woven tape is often
sufficient for small boats seams.
As you write, as long as the joint is stronger that the parts, we are
OK.
For small boats, we often specify woven tape for the chine, keel and
bow seams because:
- it is sufficient
- it cost less
but for fiberglass splices, I prefer to alwasy use biaxial.

Now, if you build the whole boat with woven tape and need only 3 feet
for a splcie, it makes sense to stick to the woven tape that is
available.
For larger boats or, if I want a perfect job, I will not take that
shortcut.

(Jacques) wrote in message . com...
(Backyard Renegade) wrote

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.

Jaques
We are each correct in the sense...


How typically "Jaque'esqe"... You must be tough to work with, not that
I would pass up an opportunity. Let's all remember though, we are
still talking a two sheet canoe
Scotty