I am building a S&G canoe. I am going to use fiberglass cloth on the
entire outside for extra strength, and to prevent any checking in the
plywood. I'm useing 1/4" BCx plywood.

What weight of cloth would I want to use for this aplication? And the
next question, how would I decide that on future projects? Is there a
general rule of thumb for weight?

One last question, I know I need to tape the inside and outside with
fiberglass tape on the seams, but If I cover the whole outside with
cloth, do I still need the tape on the outside of the seams?

Thanks,

dave


email: dallyn_spam at yahoo dot com
please respond in this NG so others
can share your wisdom as well!

You don't need fiberglass.
The fabrics work a lot better with epoxy.
The wet out is fantastic.
The question a bit hard to answer since people use weights from one ounce up
to six or more.
A lot of builders only use tape on the inside. You can find the synthetics.
Dynel, Olifin.,Xynole,Vectra at http://www.defender.com/
Once you use the fabrics you never go back to fiberglass

"Dave Allyn" wrote in message
...
I am building a S&G canoe. I am going to use fiberglass cloth on the
entire outside for extra strength, and to prevent any checking in the
plywood. I'm useing 1/4" BCx plywood.

What weight of cloth would I want to use for this aplication? And the
next question, how would I decide that on future projects? Is there a
general rule of thumb for weight?

One last question, I know I need to tape the inside and outside with
fiberglass tape on the seams, but If I cover the whole outside with
cloth, do I still need the tape on the outside of the seams?

Thanks,

dave


email: dallyn_spam at yahoo dot com
please respond in this NG so others
can share your wisdom as well!

Twilk wrote:
You don't need fiberglass.
The fabrics work a lot better with epoxy.
snip

Most general purpose fabrics are in fact fiber glass, and that includes
ccloth and tape.

Weights are expressed in ounces/square yard.

Most tape is about 6 oz.

HTH

Lew

Wrong
They are not fiberglass and they also do not make you itch.
They are in fact' Polypropylene and polyester-

"Lew Hodgett" wrote in message
ink.net...
Twilk wrote:
You don't need fiberglass.
The fabrics work a lot better with epoxy.
snip

Most general purpose fabrics are in fact fiber glass, and that includes
ccloth and tape.

Weights are expressed in ounces/square yard.

Most tape is about 6 oz.

HTH

Lew

On Thu, 17 Feb 2005 22:40:47 GMT, Lew Hodgett
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

Lew

Twilk is referring to Dynel etc. They are excellent sheathing
materials. They are not as stiff as glass when dry, though IME, and so
are not used solely as structural materials. They do "give" a lot more
and that can be an advantage in composite wood/fibre work.

IIRC again. My main gripes we
- $$
- they were not as transparent as glass/resin
- they get "fur" when you sand them

Twilk wrote:
You don't need fiberglass.
The fabrics work a lot better with epoxy.
snip

Most general purpose fabrics are in fact fiber glass, and that includes
ccloth and tape.

Weights are expressed in ounces/square yard.

Most tape is about 6 oz.

HTH

Lew

On Thu, 17 Feb 2005 15:17:50 -0600, Dave Allyn
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

I am building a S&G canoe. I am going to use fiberglass cloth on the
entire outside for extra strength, and to prevent any checking in the
plywood. I'm useing 1/4" BCx plywood.

What weight of cloth would I want to use for this aplication? And the
next question, how would I decide that on future projects? Is there a
general rule of thumb for weight?

A _rough_ rule of thumb is that if you use full thickness of ply as
designed, and only want this to stop checking and help keep the wood
dry, then use a really light cloth, but reinforce all corners, as
that's where most abrasion is. Also two layers on the bottom. If you
use thinner ply, then build up with cloth until the boat weighs the
same as it would have in ply (reasonably well-laid glass cloth will
take up its own weight in resin, roughly), and you will probably have
a stronger boat.

Otherwise, talk to the canoe's designer. Always a good idea.


One last question, I know I need to tape the inside and outside with
fiberglass tape on the seams, but If I cover the whole outside with
cloth, do I still need the tape on the outside of the seams?

Unless you can cover the whole boat with cloth before you move it from
the building jig, then yes. It's literally what holds the whole boat
together.

On Fri, 18 Feb 2005 08:11:18 +0800, OldNick
wrote:
A _rough_ rule of thumb is that if you use full thickness of ply as
designed, and only want this to stop checking and help keep the wood
dry, then use a really light cloth, but reinforce all corners, as
that's where most abrasion is. Also two layers on the bottom. If you
use thinner ply, then build up with cloth until the boat weighs the
same as it would have in ply (reasonably well-laid glass cloth will
take up its own weight in resin, roughly), and you will probably have
a stronger boat.

So, probably tape chines, inside and out, cover entire boat again
with like a 4 ounce glass and then throw a second layer of 6oz, or a
synthetic, on the bottom, and maybe wrap it a couple of inches up the
sides.

Otherwise, talk to the canoe's designer. Always a good idea.

Will do.

One last question, I know I need to tape the inside and outside with
fiberglass tape on the seams, but If I cover the whole outside with
cloth, do I still need the tape on the outside of the seams?

Unless you can cover the whole boat with cloth before you move it from
the building jig, then yes. It's literally what holds the whole boat
together.

I don't have a building jig on this design. It is a simple canoe with
only two "corners"--One chine in the middle of the side, and then a
chine where it hits the bottom. Not sure if that would be considered
one chine or two, but either way it is a simple design.


dave


email: dallyn_spam at yahoo dot com
please respond in this NG so others
can share your wisdom as well!

On Sat, 19 Feb 2005 13:06:47 -0600, Dave Allyn
vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

So, probably tape chines, inside and out, cover entire boat again
with like a 4 ounce glass and then throw a second layer of 6oz, or a
synthetic, on the bottom, and maybe wrap it a couple of inches up the
sides.

The second layer at 6 0z may be only 4? Watch the weight. You have to
carry this thing. Looking at the canoe as a 2' 6" half tube 5 yards
long, 10 oz of glass + resin = 28 lbs!

A lot depends on your usage. If you are goping to simply work open
water with the occasional beach landing, then leave it at 1 layer. If
you are going to be really bashing it about, go for 2 layers.

The one that interested me was Syntex, where they showed 2.8 oz cloth
holding up better than 6oz of glass. But I bet it's $$$$. And they
said it was a bitch to cut.

I don't have a building jig on this design. It is a simple canoe with
only two "corners"--One chine in the middle of the side, and then a
chine where it hits the bottom. Not sure if that would be considered
one chine or two, but either way it is a simple design.

Ok. Make sure the boat is very straight and true before you tape the
outside seams particularly. That is probably my point.

On Sun, 20 Feb 2005 06:54:08 +0800, OldNick
wrote:
So, probably tape chines, inside and out, cover entire boat again
with like a 4 ounce glass and then throw a second layer of 6oz, or a
synthetic, on the bottom, and maybe wrap it a couple of inches up the
sides.

The second layer at 6 0z may be only 4? Watch the weight. You have to
carry this thing. Looking at the canoe as a 2' 6" half tube 5 yards
long, 10 oz of glass + resin = 28 lbs!

Does the strength come from layers or weight? i.e.: would one layer
of 12 oz be as good, better, or worse than two layers at 6 oz? or
three layers of 4 oz, 6 layers of 2oz 24 layers of 1/2 oz....etc....
I know in plywood, the more layers withina givin thickness, the
stronger the plywood. is it the same in fiber/epoxy?



A lot depends on your usage. If you are goping to simply work open
water with the occasional beach landing, then leave it at 1 layer. If
you are going to be really bashing it about, go for 2 layers.

To be honest, I am building this more because I saw the idea in a
magazine and it peaked my intrest. I rarely canoe, and it will
probably only see water a few times a year. In the off time it will
be stored in a shed, out of direct sunlight.

The one that interested me was Syntex, where they showed 2.8 oz cloth
holding up better than 6oz of glass. But I bet it's $$$$. And they
said it was a bitch to cut.

I've heard that about kevlar as well...

I don't have a building jig on this design. It is a simple canoe with
only two "corners"--One chine in the middle of the side, and then a
chine where it hits the bottom. Not sure if that would be considered
one chine or two, but either way it is a simple design.

Ok. Make sure the boat is very straight and true before you tape the
outside seams particularly. That is probably my point.

So noted. Thanks.

dave


email: dallyn_spam at yahoo dot com
please respond in this NG so others
can share your wisdom as well!

Dave Allyn ) writes:

To be honest, I am building this more because I saw the idea in a
magazine and it peaked my intrest. I rarely canoe, and it will
probably only see water a few times a year. In the off time it will
be stored in a shed, out of direct sunlight.

You can save yourself a lot of time and mess by just taping the seams and
painting or varnishing the hull. On my small plywood boats I don't even
tape the seams, just round off smooth the outside of the edges with a
sanding disk on my drill and then apply 2 layers of polyester resin along
the seams to seal and protect the exposed plywood edge. You have to seal
all the exposed plywood edges on the boat anyway to keep moisture from
getting into the edges where the end grain of the wood is open. I mix a
small amount (1 teaspoon) of resin at a time and spread it along the edge
with a toothpick. To each teaspoon of polyester resin you have to add 2
drops of hardener. I touch up the paint each spring and sometimes mid
season as well. (Photos of the boats on my website, see below.) I keep a
boating log which shows I go out about 30 times a season, usually for an
afternoon or evening.

Also seal the gunnel, top and bottom, if the boat is ever going to be
stored outside upside down, especially over the winter. Water will drain
off the bottom of an overturned boat and collect along the gunwale where
it can sit and rot. It will also hang and drip of the top of the gunwale
of an overturned boat. I've had to repair delmainating and rotting plywood
edges along a gunwale after storing a home built boat outside inverted over
the winter. The keel, skids, and bottoms have never been a proboem stored
upside down because water does not collect on them.

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