Fiberglass weight
 

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 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

This may be of interest
http://www.oneoceankayaks.com/Abrasion.htm

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

It is a good idea to double up the glass on all joints. If you are not after a clear finish then Dynel is a good choice on the exterior over the glass tape on the joints. The Dynel will give you better abrasion resistance and will work better to stop the checking in the plywood.
---Joel---

Dave Allyn wrote:

For information like this, there are better places for you to ask than
here. I suggest posting on the kayak building forum at kayakforum.com.

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?

Most canoe and kayak builders use 6 oz. cloth, typically one layer over
the entire outside of the hull and often a second layer over just the
high wear "football" area on the bottom. Another common and lighter
alternative is 4 oz. cloth.

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?

No it's not necessary, but extra wear protection on the chines is a good
idea. The outside should be completely glassed for durability. How much
glass/tape you use on the outside depends on how rugged you want the
boat to be.

What you need to do on the inside is to fillet the seams to provide a
smooth transition between the panels, then glass over the fillets. If
you do decide to fully glass the interior (not a bad idea), you can skip
the tape there, too. If you don't fully glass the interior, the rest of
the interior plywood surface should be covered with epoxy to seal it.

Once the boat is glassed, all surfaces that will be exposed to the sun
must be varnished or painted to provide UV protection. Otherwise,
sunlight will break down the epoxy over time.

I believe Olifin is even tougher than Dynel.
Some builders do awesome stuff with combinations laying them at 45 degree
angles and such.

"boatbuilder.org" wrote in
message ...

It is a good idea to double up the glass on all joints. If you are not
after a clear finish then Dynel is a good choice on the exterior over
the glass tape on the joints. The Dynel will give you better abrasion
resistance and will work better to stop the checking in the plywood.
---Joel---


--
boatbuilder.org