1708 tape vs cutting strips, which is better???

[DualCore]

I have another fiberglass question that I have not been able to find an answer to on the other posts, it's about fiberglass tape. I was looking at the products on the US Composites site and noticed that they have 1708 in a pre-sized tape (6" & 12" wide). It seemed to me that this would be great for tabbing but since I have not read anything about fiberglass tape on the forums I started to wonder if it was not as good as cutting strips from a full piece of cloth for some reason. So my question is; is there any reason not to use 1708 tape for tabbing (transom/stringers/sole)?

 

[Mark42]

Re: 1708 tape vs cutting strips, which is better???

Its easy to cut 1708 into whatever size strip you want. I used a yard stick and a razor knife and cut on an old piece of plywood. No problems. Just keep a fresh blade, and even pressure and it cuts neat and clean.

I don't know for sure, but my guess is that it is more cost effective to cut your own.

 

[92excel]

Re: 1708 tape vs cutting strips, which is better???

As Mark42 said.. it is very easy to cut to the desired size..

when you are tabbing you want to increase overlap.. so your first tab lets say i 6 inches wide.. you want to follow that with 8 inches. so if you bought tape then you would need to buy two different rolls.

i debated the same thing.. but i also had to do my transom and cant do that with tape so the 38 inch wide roll is what i went with

 

[erikgreen]

Re: 1708 tape vs cutting strips, which is better???

What I do is offset the tape runs. It doesn't have to overlap on both sides in the same layer. You can place one layer offset low, one offset high, and you'll end up with pretty much the same thickness in the same places as multiple widths.

I like tape because it saves valuable time... it's well and good to cut your own, but to do that you need to spread out the cloth somewhere, keeping it clean at the same time, measure, cut, change blades, fix miscuts, etc.

It's much, much easier to whip out the roll of tape and cut it to length. It's also generally neater looking unless you're particularly good at cutting glass.

The only thing I don't like about US Composites tape is the fact that they don't have a version without mat. If you're using epoxy you don't need mat, and it makes the stuff harder to handle. I prefer bateau.com's tape, since it's just the biax fabric, and it's a bit cheaper than US Composites.

One final thing... don't cut with a razor knife or utility knife.. it's too hard to do cleanly. Get yourself one of the roller knives that sewing folks use... some of these are expensive models with replaceable blades, I personally use a plastic fiskars model. They cut glass as easily as cloth, you just need a flat surface to press the glass against, preferably wood or cutting mat. Much easier than a razor knife, straighter cuts, etc.

Here's a link:
http://www.amazon.com/Fiskars-95217...=UTF8&s=office-products&qid=1238598981&sr=8-3

Erik

PS: Answer to original question: No, no reason not to use it unless you don't like having the mat in there or don't like the cost.

 

[jonesg]

Re: 1708 tape vs cutting strips, which is better???

I much prefer tape but it costs more, if I cut from loose weave cloth rolls I sometimes apply masking tape then cut along the centerline of the tape leaving half on the peice I cut , the rest stays on the end of the roll, keeps it neat.
Thats not necessary on woven cloth though.

 

[DualCore]

Re: 1708 tape vs cutting strips, which is better???

Thanks guys, that's pretty much where my thinking was, costs a little more but involves a lot less cutting and the edges don't unravel.

erikgreen, I'm planning on using Poly so I need the mat backing. I was toying with the idea of using Epoxy but I'm afraid that the cost difference would be too great...

 

[erikgreen]

Re: 1708 tape vs cutting strips, which is better???

It's up to you of course, but unless you're using bond-o or equally cheap poly, the price isn't that much more. Check out uscomposites.com epoxy... 1.5 gallons of epoxy for $65 or so.

Nothing wrong with poly if you know how to use it, and you get that mat in there.

Erik

 

[WizeOne]

Re: 1708 tape vs cutting strips, which is better???

Check out uscomposites.com epoxy...

No longer there Erik. Seems to have been taken over by:

http://www.fgci.com/

P**s poor website. Limited selection of epoxies, no description on what they have, or for their glass, for that matter and they make you call for prices!

CORRECTION: I just google them. Somehow my USC bookmark got redirected to this fgci.com. I wonder how that happened?

http://www.uscomposites.com/

 

[erikgreen]

Re: 1708 tape vs cutting strips, which is better???

Could be a bookmark problem. Or, it's technically possible for one company to insert invalid information into the DNS servers of another company, but it's really rare.

Do you have an fcgi bookmark somewhere in your computer, or did you visit any pages where a link would have been to fcgi?

It's possible to click on a link... have nothing happen right away, then when you click somewhere else or pull up a bookmark, the first link comes up since it was delayed.

I'm just glad they're not gone

 

[DualCore]

Re: 1708 tape vs cutting strips, which is better???

erikgreen, I like the idea of using Epoxy but I'm concerned about how much resin it would take for the project. I can get Poly from a local supplier for $130 for 5 gallons with no shipping. The 6.5 gallon Epoxy kit from US Composites is $243 plus probably around $30 for shipping which is almost double the cost of the Poly.

Even at that I would still consider using the Epoxy if I was pretty sure that one 6.5 gallon kit would be enough but my fear is that it won't be enough and I'll end up needing another kit.

I have a 16 foot tri-hull with a 70" beam and I'm doing a full width transom, 3 stringers, at least 2 cross members for sole support and a full sole (about 68" x 9'). Do you think I would have a shot at getting all of this glassed with one 6.5 gallon Epoxy kit?

If I do bite the bullet and go with Epoxy I will need to rethink my glass choices too. Most of the reading I've done so far was with Poly. If I have this straight, with Epoxy you don't need mat just cloth right? How many layers of cloth at what weight would be required?

With the Poly my plan was to use 2 layers of 1708 tabbing and 2 complete covers of 1708 on the transom, what would that translate to in the Epoxy world.

Sorry for all the questions, I just really want to get this right. And I want to make sure I know what I'm getting into before I place my order...

 

[erikgreen]

Re: 1708 tape vs cutting strips, which is better???

The same layers of 17 oz glass would be plenty strong for epoxy. Two on the stringers and two on the transom is fine.

Ideally you want about a 1:1 or so ratio of epoxy to glass, so if you use 1 kg of glass you want 1 kg of epoxy to wet it out.

I'd have to do some calculations, but that's an awful lot of epoxy.

I'm using a 6.5 gallon kit for the first stage of my new boat... it's enough to let me laminate my transom and stringers, butt join my hull panels, glass the hull joints with tape, cover the outer hull with a layer of 12 oz. glass (it's a 19 foot boat) and mix filler for all the above. I'll still have some left.

When I did my transom I only needed 2 gals for that, and I used a lot more than a needed to...

Erik

 

[DualCore]

Re: 1708 tape vs cutting strips, which is better???

When you say 2 layers of 17oz on the transom and stringers does that include tabbing? Or would it be 2 layers of tabbing and 2 complete covers? Should I use 17oz biax or would regular cloth work? I looked at US Composites and they don't carry a 17oz cloth would 3 layers of 10oz be close enough (or would 2 of 18oz be better)?

What weight of tape did you use for your for you hull joint? I'm only finding 8.7 oz on US or 12oz biax on bateau.

Thanks for all you help Eric, I think I'm starting to get a better handle on all of this. There's just so much to learn...

 

[erikgreen]

Re: 1708 tape vs cutting strips, which is better???

When you say 2 layers of 17oz on the transom and stringers does that include tabbing? Or would it be 2 layers of tabbing and 2 complete covers? Should I use 17oz biax or would regular cloth work? I looked at US Composites and they don't carry a 17oz cloth would 3 layers of 10oz be close enough (or would 2 of 18oz be better)?

What weight of tape did you use for your for you hull joint? I'm only finding 8.7 oz on US or 12oz biax on bateau.

Thanks for all you help Eric, I think I'm starting to get a better handle on all of this. There's just so much to learn...

My boat's a bit different from yours since it's a scratchbuild, but I can comfortably say if you use all of a 6.5 gallon epoxy kit to do your stringers and transom you've probably used too much

For my hull joints the designer specified 12 oz. tape, 2 layers overlapping on the outside, then a layer of 12 oz biax cloth, and both of these are on top of epoxy glue at the edges of the panels and the cloth layers overlap at the keel.

For your needs, I think 3 layers of 10 oz would be plenty, as would using woven roving or cloth in the same amount. Biax is easier to work with and a bit stronger for the same weight due to the fiber orientation. The critical thing is to build up the thickness you need using something other than mat. As long as there's enough thickness of oriented fibers there you'll have the strength you want. You can use 15 layers of 2 oz if you really want to.

It's up to you whether you cover the stringers completely. For the type of construction you're doing it adds some strength, but mostly just protects the stringers against abrasion and water.

Here's my suggestions for your layup with epoxy:

Stringers: Two layers tabbing, 17 oz biaxial tape. 6 inch wide then 8 inch wide. Including the mat won't hurt if you just want to order from US Composites instead of hunting around. It'll add some strength, but mostly it'll soak up extra epoxy.

Transom: Tab edges with two layers of 17 oz biax as above and cover with one layer of 12-ish oz woven cloth, overlapping all edges.

If you want to substitute plain woven cloth or roving, I'd add about 10 percent weight to match strength, so four layers of 10 oz fabric tabbing would roughly equal the two layers of biax... assuming there aren't any problems in layup.

Note that this is the layup for home builders.. it's actually overkill in strength for this use to leave some room for errors in application, unforeseen stresses, etc.

Ondarvr may have some suggestions for you too, he's mr glass

Erik