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Why 1708 biaxial????

Old 04-14-2019, 03:51 PM
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Default Why 1708 biaxial????

I've been reading tons and tons of boat builds as I plan to start on my new (and first) boat project. I noticed that in all of these builds everyone is using 1708 biaxial for their fiberglass. Im not familiar with it and I'm far from an expert at fiberglass work so my question is why is that everyones choice?
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Old 04-14-2019, 04:02 PM
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It's a good general purpose glass. Good strength in any direction, does not need too much resin, and can be molded into (gentle) curves.

I built a cold molded 38, used 1708 inside and outside of hull. Pilot house and deck got 1208.
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Old 04-14-2019, 04:05 PM
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You need to compare them next to each other. I use a fair amount of 1708 for rebuilds and repairs. Each fiberglass cloth has it's place in a repair. You don't just use 1708 and that's it. As for use it 's easy to work with and the Biaxial weave gives it strengths in multiple directions.
I'm sure you will get more answers but I'm just trying to keep it simple.
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Old 04-14-2019, 04:47 PM
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go over to boatbuildercentral.com they have a good how to page and how to use different products they also sell almost everything you will need.... but boatbuildercentral is slightly more expensive

have a a look at us composites for supplies
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Old 04-14-2019, 08:01 PM
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Originally Posted by classic162 View Post
You need to compare them next to each other. I use a fair amount of 1708 for rebuilds and repairs. Each fiberglass cloth has it's place in a repair. You don't just use 1708 and that's it. As for use it 's easy to work with and the Biaxial weave gives it strengths in multiple directions.
I'm sure you will get more answers but I'm just trying to keep it simple.
I guess what Im trying to ask is since you still need to lay a chop strand mat in conjunction with the 1708 why not just use a woven mat and a chop strand mat. You may have to do some more layers doing it that way but wouldn't you still come out with the same result and maybe even a little cheaper since the 1708 is so expensive?
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Old 04-15-2019, 06:24 AM
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1708 comes with its own chop strand mat on the bottom, no need for separate mat.
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Old 04-15-2019, 08:28 AM
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Originally Posted by THE SALTY FIREMAN View Post
I guess what Im trying to ask is since you still need to lay a chop strand mat in conjunction with the 1708 why not just use a woven mat and a chop strand mat. You may have to do some more layers doing it that way but wouldn't you still come out with the same result and maybe even a little cheaper since the 1708 is so expensive?
there's 1700 biaxial and there's 1708 biaxial.
the "08" part means it has 3/4oz. mat on the backside (.75 rounded up?).
the "17" part is 17 oz biax.
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Old 04-15-2019, 08:36 AM
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1708 is for Ester resins
1700 is for epoxy

The 08 mat is a filler, doesn't have substance to it is mainly used to make the cloth go around corners and stay there.
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Old 04-15-2019, 08:48 AM
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Originally Posted by THE SALTY FIREMAN View Post
I guess what Im trying to ask is since you still need to lay a chop strand mat in conjunction with the 1708 why not just use a woven mat and a chop strand mat. You may have to do some more layers doing it that way but wouldn't you still come out with the same result and maybe even a little cheaper since the 1708 is so expensive?
In most applications 1708 has better physical properties when compared to a woven product. So in many situations you can either make the part lighter with the same strength, or stronger with the same weight when using 1708 in place of roving.

It just gives a person more options in choosing the laminate schedule.

For decades it wasn’t as easy to buy in the DIY market, but now it’s everywhere.
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Old 04-15-2019, 09:05 AM
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From what I understand, Biaxial fabrics are favored because the tows are laid straight in the laminate. Straight fibers, when loaded, quickly become engaged to resist tension. Woven fabrics on the other hand are s-shaped, and expend some strength in side loading. Think of how a rope is used; If it's a straight line all the load is in line, and all of the strength is used to do the desired work. If you were to take that same line and weave it back and forth through a series of nails, some line strength would be engaged in bending the nails to allow the line to straighten out and the line would effectively stretch further before becoming fully loaded.

Both 1708 and 1700 can be used with epoxy. The mat allows fiber to pack more closely between layers and provides some off axis strength. With polyesters the mat gives better peel strength.
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Last edited by smccormick; 04-16-2019 at 11:51 PM.
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Old 04-15-2019, 01:02 PM
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Originally Posted by ondarvr1 View Post


In most applications 1708 has better physical properties when compared to a woven product. So in many situations you can either make the part lighter with the same strength, or stronger with the same weight when using 1708 in place of roving.

It just gives a person more options in choosing the laminate schedule.

For decades it wasn’t as easy to buy in the DIY market, but now it’s everywhere.
It may be everywhere but I still wouldn't call it easy to get lol. Fiberglass, resin, epoxy etc. is ridiculously expensive.
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Old 04-15-2019, 01:30 PM
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Originally Posted by THE SALTY FIREMAN View Post
Fiberglass, resin, epoxy etc. is ridiculously expensive.
ought to make a sticky of that!
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Old 04-15-2019, 01:31 PM
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Originally Posted by THE SALTY FIREMAN View Post
Fiberglass ridiculously expensive.
Ever priced a machine to manufacture 1708?
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Old 04-15-2019, 01:35 PM
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Originally Posted by bills106 View Post
ought to make a sticky of that!
The stuff is already sticky!
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Old 04-15-2019, 05:42 PM
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Originally Posted by Fordy View Post
1708 is for Ester resins
1700 is for epoxy

The 08 mat is a filler, doesn't have substance to it is mainly used to make the cloth go around corners and stay there.
Even with epoxy The mat makes it easier to get a good laminate. In my experiance
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