It's easier to get good wet out with layers of lighter cloth.
It could make a big difference depending on the skill of the builder.

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 wrote:
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?

More layers of thinner cloth will be stronger and more flexible than a
single layer of heavier cloth.

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---

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

On Fri, 18 Feb 2005 02:17:01 +0000, boatbuilder.org
wrote:
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.

After reading here, I will definatly double up the joints and the
bottom. Is there much of a cost differance for the Dynel vs. the
fiberglass? Also, can I mix and match? Maybe Dynel on the bottom
with glass on the sides? or do they not wet out the same?

dave


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

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.

On Fri, 18 Feb 2005 14:25:05 GMT, Brian Nystrom
wrote:

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'll check it out. Thanks!

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.

Is there a disadvantage for the 4oz? not over the chines or the
bottom, but over the rest of the sides?

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.

Ah.. okay.




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

Note that the weigth of fibreglass and resin together is 96 lb per cubic
foot (Skeen's Elelments of Yacht Design, 30% fibregalss, 70% resin), and
a 1/4" thick layer is 2 lb per square foot. That makes 1/8" layer 1 lb
per square foot, and 1/16" layer half a pound per square foot. I don't
know how thick the various weights of cloth are, Perhaps you could find out.
The cloth has to be more than filled out to it's thickness with resin to
cover the thread and have a smooth hull. There's also the matter of getting
enough glass and resin on the fir plywood to keep it from developing little
surface cracks (checking) which it does from chages in temp and humidity.
I don't know how much is needed, Storing the boat in the shade is said to
help.

I don't know if you've started to build but meranti (luan) plywood is
cheap, rot resistant, and does not check. I assume because you are using
lumberyard plywood, as I do, that you are interested in a cheap boat. I've
built in lauan and virola (not rot resistant) and just painted. I've also
fished from cheap painted (fir and spruce?) plywood punts. You can't get
spruce plywood any more as far as I know.

Dave Allyn ) writes:
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!


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William R. Watt ) writes:

I don't know if you've started to build but meranti (luan) plywood is
cheap, rot resistant, and does not check. I assume because you are using
lumberyard plywood, as I do, that you are interested in a cheap boat. I've
built in lauan and virola (not rot resistant) and just painted. I've also
fished from cheap painted (fir and spruce?) plywood punts. You can't get
spruce plywood any more as far as I know.

I should also note that when I weighed sheets of 1/4" plywood, fir was 22
lb, lauan (meranti) 17, and virola 8.5 lb. Lauan and virola are metric and
actually 1/5". I don't recommend virola becase I don't think the boat will
last long. I have used it for the light weight and because it bends to a
tigher curve than the others.

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