3M Fiberglass??

[aspenshayn]

So I read everywhere that I should use 1708 fiberglass for my stringers. I don't have much for fiberglass options where I live unless I order online. Is 1708 comparable to or the same as 3M Fiberglass Cloth (No. 20128) or the Mat (No. 20129)? I was hoping to glass my stringer tonight, and those are my immediate options. I will be laying it with epoxy resin if that helps.

Thanks for your input!

 

[goboating]

Re: 3M Fiberglass??

Look in this section for friscoboater and his 22ft SeaRay. He has some awesome videos and lots of posts. He could answer all of your questions to. He is taking some time off due to his Mother. She is in hospice now and not doing good. If you sent him a PM he might take a few days to respond.

 

[Woodonglass]

Re: 3M Fiberglass??

NOT QUITE!!! This is a basic cloth that is about the equivalent of a 6oz cloth. 1708 means a 17oz cloth with 3/4oz CSM mat stitched to the back of it. Soooo. in order to get the same Strength you would need to apply approximately 3 layers of this cloth and that would use a LOT of epxoy. Since epoxy IS stronger than Poly you MIGHT get by with two layers.

 

[saltwaterbluefish]

Re: 3M Fiberglass??

If that is the same stuff found at Wal-Mart, Home Depot, and Lowes it is not at all comparable to 1708. The 3M is much lighter in weight and should be used mainly for cosmetic repairs. The 1708 has the cloth with the mat on oneside and is for structure. US Composities seems to be the online retailer everyone buys from, but they also explain alot of the different types of glass and what they can be used for. Remember the stringer is not where the strength is, the strength is in the glass.

 

[oops!]

Re: 3M Fiberglass??

this is sooo wayyy wrong.......dont have time to go into it all.

1708 is a standard......look at it in my link in my sig.
also....if you are using epoxy (i have no idea why???) you will not use cam of any weight....just cloth or roving......but cloth is better.

 

[aspenshayn]

Re: 3M Fiberglass??

man.. the more I read the more confused I get. must use epoxy, no need to use epoxy, cloth roving mat...

I guess I will just order the 1708 and use the epoxy resin I already have from aeromarine. should be solid when I'm done.

I was going to lay the mat and then cloth over it, but seems I should just go with the 1708.

Thanks for the input.

 

[aspenshayn]

Re: 3M Fiberglass??

Oops, Seems like you know your stuff and your thread is great, but in my situation...

I'm glassing a 19' (at the tallest 7") stringer from bow to stern. will roven over the entire stringer with epoxy resin be strong enough. 2 layers?

And do I go over the entire stringer and 4 - 6 inches out on hull on each side?

I appreciate some straight answers as this project is killing me with everyones opinions on what is right?

Thanks for help!

 

[produceguy]

Re: 3M Fiberglass??

I used the 3m glass on my transom and deck.
I used the mat as well as the cloth.It might not be the best stuff to use but it will work.

 

[Cadwelder]

Re: 3M Fiberglass??

The bottom line is the epoxy....why are you using epoxy? Polyester resin is just fine and much cheaper and easier to work with.

1708 has CS matt made into it which isn't needed with epoxy. There are many opitions to use, the 1708 is just a good standard and easy to work with. If you must go with epoxy all you need is cloth...for your stringers a 10 or 12 oz cloth will work with the epoxy.

I have used woven roven with CSM for years, and just recently starting using 1708. I know some older glass guys that swear by woven and matt and there is nothing wrong with thier methods, there isn't a "set in stone" method for glassing in your stringers.

Most of the cloth I've seen at the box stores is a 6 oz. I would shy away from their resin for two reasons: First 90% of it is waxed, which you don't need or want, and secondly you have no idea how old it is, freshness is important with resins, especially polyester.

I'd strongly recommend the polyester resin....it's what your boat was built with.

Sorry you are confused....I hope this helps explain it a bit.

 

[Friscoboater]

Re: 3M Fiberglass??

I am still around, but in limited capacity. Use polyester resin, as it is fine for these boats. 1708 will have to be purchased online, or if you get lucky, locally.

 

[Yacht Dr.]

Re: 3M Fiberglass??

So I read everywhere that I should use 1708 fiberglass for my stringers. I don't have much for fiberglass options where I live unless I order online. Is 1708 comparable to or the same as 3M Fiberglass Cloth (No. 20128) or the Mat (No. 20129)? I was hoping to glass my stringer tonight, and those are my immediate options. I will be laying it with epoxy resin if that helps.

Thanks for your input!

DO NOT USE THIS GLASS FOR YOUR STRINGERS PERIOD !!

Sorry for the caps..but Its not a good thing..

NOT QUITE!!! This is a basic cloth that is about the equivalent of a 6oz cloth. 1708 means a 17oz cloth with 3/4oz CSM mat stitched to the back of it. Soooo. in order to get the same Strength you would need to apply approximately 3 layers of this cloth and that would use a LOT of epxoy. Since epoxy IS stronger than Poly you MIGHT get by with two layers.

NO YOU WILL NOT GET BY WITH 2 OR 3 OR 10 LAYERS OF THIS STUFF PERIOD !! ( Wood your a great guy..and have much to offer .. but in the Realm of Glassin Structural Things.. Stay back to your profession.. this is CrAp glass and should NOT be used on Stringers/bulks or anything else Structural ).

If that is the same stuff found at Wal-Mart, Home Depot, and Lowes it is not at all comparable to 1708. US Composities seems to be the online retailer everyone buys from, but they also explain alot of the different types of glass and what they can be used for. Remember the stringer is not where the strength is, the strength is in the glass.

SPOT ON !!

this is sooo wayyy wrong........

Again.. I agree..

man.. the more I read the more confused I get. must use epoxy, no need to use epoxy, cloth roving mat...

I guess I will just order the 1708 and use the epoxy resin I already have from aeromarine. should be solid when I'm done.

I was going to lay the mat and then cloth over it, but seems I should just go with the 1708.

Thanks for the input.

Mat first..then your 1708 .. then mat on the last layer ..

Oops, Seems like you know your stuff and your thread is great, but in my situation...

I'm glassing a 19' (at the tallest 7") stringer from bow to stern. will roven over the entire stringer with epoxy resin be strong enough. 2 layers?

And do I go over the entire stringer and 4 - 6 inches out on hull on each side?

I appreciate some straight answers as this project is killing me with everyones opinions on what is right?

Thanks for help!

Dont woven OVER the tops..just a few layers of 1.5 matt .. no epoxy..all poly..

How far out do you prep and tab..that depends on the application..( I still dont see pics or year/make/model ).

A 56 SR .. or a 10' dink ..

I used the 3m glass on my transom and deck.
I used the mat as well as the cloth.It might not be the best stuff to use but it will work.

No..that "veil" cloth is Worthless on boats .. its used for models or planes or RC cars/boats and has NO use ( Aside from pattern on nonskid that will be painted over).

YD.

 

[Woodonglass]

Re: 3M Fiberglass??

Again, I disagree. With Epoxy mat is NOT needed. Cloth is ALL that is required. Yacht Doctor show ME PROOF where I am wrong about this. Poly YES EPOXY NO He Clearly stated he was using Epoxy. And notice I SAID MIGHT. I did NOT recommend or say for him to use it. With epoxy all he needs is the 17 oz Cloth NOT the 1708 the mat is NOT necessary.

 

[Yacht Dr.]

Re: 3M Fiberglass??

NOT QUITE!!! This is a basic cloth that is about the equivalent of a 6oz cloth. 1708 means a 17oz cloth with 3/4oz CSM mat stitched to the back of it. Soooo. in order to get the same Strength you would need to apply approximately 3 layers of this cloth and that would use a LOT of epxoy. Since epoxy IS stronger than Poly you MIGHT get by with two layers.

..you suggest the OP Can in Fact use this cloth with epoxy for his stringers with approx. 3 layers (without mat beginning or ending) ??

Again, I disagree. With Epoxy mat is NOT needed. Cloth is ALL that is required. Yacht Doctor show ME PROOF where I am wrong about this.

The cloth that he is suggesting..and you seem to agree with the above post From you IS In Fact WRONG !!

Proof ?? you want me to link some Proof linky or something ?? I Am tellin you Proof !! .. Unless of course you would like me to start some kinda of Blog or put it up on Ytube....

Its Going to FAIL using these materials ..

Again..Wood..your a good guy and a most Valued member here..but your no Structural on hands Glass Pro ... Took me how many Years to get to where I am with GLASSwork.. .. how many years you got .. Dont suggest things that you dont have any Idea about

YD.

PS. Im sure I will get modded for this one too..

 

[aspenshayn]

Re: 3M Fiberglass?? pics added

Re: 3M Fiberglass?? pics added

Here are some pics of the stringer. same as what was there, or should have been...


These pics are from a few days ago, it is now cleaned and up and ready for glass.

Thanks for the input, you guys have saved me from a costly mistake.

 

[DeepBlue2010]

Re: 3M Fiberglass??

Here is what I learned reading some good projects on this site and reading The Fiberglass Boat Repair Manual by Allan H. Vaitses

Epoxy vs Poly is a heated debate around here. The consensus is if you are making a repair, better stick to the material that the boat was constructed out of. Unless you have a high performance racing boat, the odds are it was built with polyester resin. Vinyl Ester is a perfect compromise between the two (Poly vs Epoxy) and is available from USComposites for only few bucks more than their premium layup poly resin. Also, keep in mind that if you use epoxy, you can?t use polyester product on top it whether it is being gelcoat or resin to fix any damage that may happen in the future.
In your case, it seems like the only reason you want to use Epoxy is that you already have some. Did you calculate how much of it you need to glass stringers? If you have a gallon of it and you need five to finish the job, it is not a cost effective to go with Epoxy just because you have 20% of what you need.
Chopped strand mat is used as the first layer of laminate when using Polyester resin because it is
? The most water tight because of the random orientation of the strands
? The most resistant to peeling from the core material
However, CSM is lower for its weight in tensile and flexural strength than woven or unwoven roving.
The binder that holds the strands on their position is chemically dissolvable in polyester resin; more specifically by the styrene in the poly resin. While it is possible to wet the CSM with epoxy, the binder will not dissolve. It will get suspended inside the cured epoxy; whether this will compromise the strength of the epoxy or not, I can?t answer this question. However, the main reasons for using CSM with poly resin are not applicable when using epoxy. Epoxy is water tight by itself and it is much better ?glue? than poly, so there is no concern of separating from the core material.

Not all fiberglass fabrics are created equal. CSM by itself is not meant for structural strength. Woven roving has its highest strength in the direction of the warp and weft strands, which are oriented at 90 degrees to each other, and its lowest strength is across the bias or at 45 degrees to the warp and weft directions. Biaxial fabric addresses the diagonal relative weakness of the woven roving.
In short, CSM by itself is not the material to use with stringers neither is cloth which is pretty much a finishing material rather than a structural one.
Use Poly resin (Vinyl Ester is preferable) if you can with 1708 which is 17 ounce biaxial unwoven roving with an 8 ounce backing CSM.
If you insist on using Epoxy, order the biaxial with no backing CSM attached to it (Item Number DB170 on USComposites.com)
Good luck with your project

 

[ondarvr]

Re: 3M Fiberglass??

The question of what materials to use and how to use them haunts everyone at times, so you're not alone.

In the long run the type of resin you use will make little difference and so will the type of glass, that is if you do a good job, or at least a better job than when it was originally built (which isn't hard to do), so don't stress over it too much.

CSM (mat) is not needed with epoxy, all you need to use is cloth, roving, or a biax product with no mat stitched to it, 1708 has mat on it, 1700 doesn't. The 6 oz cloth will work fine with epoxy and is commonly used, it may not be the best product for this application, but using multiple layers will work fine. When you use the exact right type of glass for each application you will save weight because it will be lighter for the same strength, but each type can be used and achieve the same strength, or at least close enough, you may just need to use a little more of it.

Mat does need to be used with polyester as a first layer and between each layer of woven or stitched fabric.

On a typical repair like this on an old ski boat using the exact right glass and resin may save you a few pounds in the finished product, which in the big picture won't make much of a difference. It will make a difference in the new construction of a high dollar go fast boat where money is no object, in this application you may be able to save several hundred pounds.

I almost never use cloth like the 6 oz product you asked about when using polyester resin, but it is a very common product used with epoxy and it works great with it. In this application 1700 would be a better choice, but either will work.

Your boat has old school construction using polyester resin plus mat and roving, is it the "perfect laminate" no, but it works. You can use the same products to rebuild it and it will hold up for many decades to come, using better products may help it last a longer, or be a few pounds lighter, but that's about it.

How long it lasts and how well it holds up depends less on the products chosen and more on how well you use those products.

 

[aspenshayn]

Re: 3M Fiberglass??

My plan is to go with the 1708 and poly resin. I will use the 3 gallons of epoxy resin I already have for other things.

Ok, so one full wrap of the 1708 or should I lay down 2 layers.... for my application.

Again, thanks for helping get me through this.

 

[DeepBlue2010]

Re: 3M Fiberglass??

I would use 1708 layers for sure. The first is 6 inches and the second 12. The are already 1708 tapes with these sizes available from USComposites.
Are you reinforcing the stringers or replacing them? If these are new stringers, they need to be bedded on PL or PB. Don't just lay them down on the hull.

 

[relocyo]

Re: 3M Fiberglass??

I like Jays sea ray thread, oh, or his glastron.... Seems to have it all there... Oh or maybe his youtube vids too... Looks like hes got it.... I mean... Dang.....

 

[rickryder]

Re: 3M Fiberglass??

And the next question.....hows the transom? Did you check if there is any rot there? Are your stringers coming out and new ones being installed? There is more information needed to get all the information you need to repair your boat.