Fiberglass
Fiberglass
Jacques put a good writing out describing differences in fiberglass and when and where they are used. I’m still a bit green with this stuff. He said never use CSM I take it that means CSM by itself. But 1708 has CSM backing? Correct? or is there a 1708 without CSM backing? I’m thinking if it has CSM at all it has the binder that don’t work well with Epoxy. I’m probably wrong but correct me.
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Re: Fiberglass
The topic was locked. But I will at least fill in a few blanks.
1208 and 1708 are mat backed stitched fabrics.
They can be used with epoxy. The csm portion of the fabrics are typically fashioned with a binder that breaks down in ester. The epoxy does not break it down, but does not need to for adhesion.
They come with a significant weight penalty. 8 ounces per sqft or 7.2 ounces per yard, so 1208 is a 19.2 ounce cloth and 1708 is a 24.2 ounce cloth. Of course, the weight penalty doubles with resin, so 14.4 ounces per yard is the real penalty.
But, there is a value in these fabrics. Most of the value needs thorough cost/benefit analysis.
The major benefit is the csm backed fabrics can be wetted and moved to the boat. And you can apply them on ceilings or walls or upside down and they do not deform as easily (but will). You can wet them on a table and roll them up and lay hundreds of feet of the stuff in an hour. And the work is neater.
Very few of the Merten's designed boats would need csm backed fabrics, if any, as I understand it.
My boat used csm backed fabrics in several places. All my tabbing used them. This allowed me to wetout tapes in 3 pound or 10 pound batches and move them to the boat on a cardboard. The weight penalty is several hundred pounds which equates to 150 pounds of resin or about 17 gallons excess epoxy. I regret using 1708 and believe 1208 tapes would have saved me 5 ounces per yard or maybe a 200 pound penalty or 11 gallons epoxy or so.
Bottom line. Csm backed fabrics have a place in boat building, but fair to say very little in the Merten's designs.
Further, csm can be used if you simply want to create a mould or something nonstructural like a lid. However, they make damned heavy components and there are much better options. Csm makes a handy hole patching material; the fabric can be laid in a hole and smaller and smaller bits of the stuff can fill the hole to near flat.
Hope it helps.
1208 and 1708 are mat backed stitched fabrics.
They can be used with epoxy. The csm portion of the fabrics are typically fashioned with a binder that breaks down in ester. The epoxy does not break it down, but does not need to for adhesion.
They come with a significant weight penalty. 8 ounces per sqft or 7.2 ounces per yard, so 1208 is a 19.2 ounce cloth and 1708 is a 24.2 ounce cloth. Of course, the weight penalty doubles with resin, so 14.4 ounces per yard is the real penalty.
But, there is a value in these fabrics. Most of the value needs thorough cost/benefit analysis.
The major benefit is the csm backed fabrics can be wetted and moved to the boat. And you can apply them on ceilings or walls or upside down and they do not deform as easily (but will). You can wet them on a table and roll them up and lay hundreds of feet of the stuff in an hour. And the work is neater.
Very few of the Merten's designed boats would need csm backed fabrics, if any, as I understand it.
My boat used csm backed fabrics in several places. All my tabbing used them. This allowed me to wetout tapes in 3 pound or 10 pound batches and move them to the boat on a cardboard. The weight penalty is several hundred pounds which equates to 150 pounds of resin or about 17 gallons excess epoxy. I regret using 1708 and believe 1208 tapes would have saved me 5 ounces per yard or maybe a 200 pound penalty or 11 gallons epoxy or so.
Bottom line. Csm backed fabrics have a place in boat building, but fair to say very little in the Merten's designs.
Further, csm can be used if you simply want to create a mould or something nonstructural like a lid. However, they make damned heavy components and there are much better options. Csm makes a handy hole patching material; the fabric can be laid in a hole and smaller and smaller bits of the stuff can fill the hole to near flat.
Hope it helps.
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Re: Fiberglass
I will add a couple of things. Pound for pound fibreglass is a very flexible material. 1208 and 1708 and other materials with a mat backing build bulk more quickly. Fibreglass will reach the needed strength long before it reaches the needed stiffness. So you can make a thicker laminate of all glass or you can use some form of core to get the needed stiffness. Wood is very stiff pound for pound but if used it needs epoxy to be used with it or you will get water ingress. Some other cores can be used with epoxy or poly. CSM is made for poly and the binder will break down so it becomes almost like cold honey and that makes it easy to shape and fill. 12 oz biax is very easy to work with and is what is called for in most of the plans here. The BOM for each plan tells you what to use. Fallguy is building a foam core boat where epoxy is needed. Also because the foam is not as stiff as wood he needs heavier glass laminates. And for puncture resistance.
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Re: Fiberglass
I'll add a few things as well.
CSM has a couple of other benefits that don't really apply to these boats:
It provides better interlaminar bonding between layers of woven roving. CSM is resin rich and the squishy nature of this provides a good bonding surface between layers of roving. This matters for polyester, but not for epoxy. I learned this when trying to remove glass laid in epoxy from my boat. It was not easy!
CSM has equal strength in all directions on the plane in which it's laid. It's even stronger than biaxial glass laid in epoxy if the load is not aligned with the fibres.
In these boats strength is provided by both the wood and the glass. The layers cover 0/45/90/135 degrees providing strength in all directions. The designer anticipates the direction of loads and fibres are laid to carry the loads. Stringers and frames provide global strength. Since the glass is laid on a core material that provides both strength and resistance to penetration, thin layers are fine. In small foam core boats the skins need to be much thicker than required for either stiffness or strength just to prevent penetration from impacts. Or thin skins used and the risk of damage accepted.
In short using CSM will add a little strength, a fair bit of stiffness (but less than using a thicker core at the same weight) and a lot of weight and cost. If that trade of is ok to you, use it. In some boats it's an option.
CSM has a couple of other benefits that don't really apply to these boats:
It provides better interlaminar bonding between layers of woven roving. CSM is resin rich and the squishy nature of this provides a good bonding surface between layers of roving. This matters for polyester, but not for epoxy. I learned this when trying to remove glass laid in epoxy from my boat. It was not easy!
CSM has equal strength in all directions on the plane in which it's laid. It's even stronger than biaxial glass laid in epoxy if the load is not aligned with the fibres.
In these boats strength is provided by both the wood and the glass. The layers cover 0/45/90/135 degrees providing strength in all directions. The designer anticipates the direction of loads and fibres are laid to carry the loads. Stringers and frames provide global strength. Since the glass is laid on a core material that provides both strength and resistance to penetration, thin layers are fine. In small foam core boats the skins need to be much thicker than required for either stiffness or strength just to prevent penetration from impacts. Or thin skins used and the risk of damage accepted.
In short using CSM will add a little strength, a fair bit of stiffness (but less than using a thicker core at the same weight) and a lot of weight and cost. If that trade of is ok to you, use it. In some boats it's an option.
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Re: Fiberglass
A great point on the stiffness. To be clear, my build only uses stitched glass due to the foam. The only place we used csm backed materials was to make the beam sockets where stiffness was needed and to laminate them into the hull because it is seriously difficult upside down and vertical lamination work. I still threw a couple pieces in the bin that got misshapen. But I want folks to know, the boat does not use CSM much except for tabbing and the beam areas. The primary hull laminate is triaxial glass and we used 1700 and 1200 quite a lot as well when the triax was too much. I apologize if I seem to detract. Bottom line foam does not require csm either.Fuzz wrote: ↑Thu Feb 18, 2021 2:34 am I will add a couple of things. Pound for pound fibreglass is a very flexible material. 1208 and 1708 and other materials with a mat backing build bulk more quickly. Fibreglass will reach the needed strength long before it reaches the needed stiffness. So you can make a thicker laminate of all glass or you can use some form of core to get the needed stiffness. Wood is very stiff pound for pound but if used it needs epoxy to be used with it or you will get water ingress. Some other cores can be used with epoxy or poly. CSM is made for poly and the binder will break down so it becomes almost like cold honey and that makes it easy to shape and fill. 12 oz biax is very easy to work with and is what is called for in most of the plans here. The BOM for each plan tells you what to use. Fallguy is building a foam core boat where epoxy is needed. Also because the foam is not as stiff as wood he needs heavier glass laminates. And for puncture resistance.
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Re: Fiberglass
You don't have to worry about binders/epoxy with the 08s because they are stitched and have no binder. But to answer the first question, 1700 is the glass without any CSM at all. This is the route I would go...especially with epoxy. The CSM will soak up extra resin, and it doesn't add much in the way of strength. 1700 is all you need with epoxy.
Re: Fiberglass
Chris L the 1708 sold here does not have CSM. It is designed to work with epoxy exclusively. !708 is basically used to build thickness and/or protection, the XF20 is a good example. If you are only using fiberglass for strength use 1700 no need for the mat. Your bill of materials should dictate which you need to use.
Tom
Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978
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Re: Fiberglass
All 1708 has csm. And all csm uses a binder to keep it from falling apart. If you can point me to a tds on 1708 for epoxy; that'd be something new to me.TomW1 wrote: ↑Fri Feb 19, 2021 12:42 am Chris L the 1708 sold here does not have CSM. It is designed to work with epoxy exclusively. !708 is basically used to build thickness and/or protection, the XF20 is a good example. If you are only using fiberglass for strength use 1700 no need for the mat. Your bill of materials should dictate which you need to use.
Tom
Hard to say this without a tone. Apologies in advance.
Re: Fiberglass
Why would Jeff buy a product with Clorosulfonated Polyethelene(CSM) when he knows it would not work with epoxy. Why don't you call him and talk to him. I have done some research and some 1708 is stitched on and it does not use CSM. Thus epoxy is fully compatible with it. Otherwise as far as my research is concerned CSM is not compatible with epoxy. So take it for what you want, no apology needed.fallguy1000 wrote: ↑Fri Feb 19, 2021 1:27 amAll 1708 has csm. And all csm uses a binder to keep it from falling apart. If you can point me to a tds on 1708 for epoxy; that'd be something new to me.TomW1 wrote: ↑Fri Feb 19, 2021 12:42 am Chris L the 1708 sold here does not have CSM. It is designed to work with epoxy exclusively. !708 is basically used to build thickness and/or protection, the XF20 is a good example. If you are only using fiberglass for strength use 1700 no need for the mat. Your bill of materials should dictate which you need to use.
Tom
Hard to say this without a tone. Apologies in advance.
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978
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Re: Fiberglass
Tom-the bond strength of epoxy doesn't care if there is a binder.TomW1 wrote: ↑Fri Feb 19, 2021 5:57 pmWhy would Jeff buy a product with Clorosulfonated Polyethelene(CSM) when he knows it would not work with epoxy. Why don't you call him and talk to him. I have done some research and some 1708 is stitched on and it does not use CSM. Thus epoxy is fully compatible with it. Otherwise as far as my research is concerned CSM is not compatible with epoxy. So take it for what you want, no apology needed.fallguy1000 wrote: ↑Fri Feb 19, 2021 1:27 amAll 1708 has csm. And all csm uses a binder to keep it from falling apart. If you can point me to a tds on 1708 for epoxy; that'd be something new to me.TomW1 wrote: ↑Fri Feb 19, 2021 12:42 am Chris L the 1708 sold here does not have CSM. It is designed to work with epoxy exclusively. !708 is basically used to build thickness and/or protection, the XF20 is a good example. If you are only using fiberglass for strength use 1700 no need for the mat. Your bill of materials should dictate which you need to use.
Tom
Hard to say this without a tone. Apologies in advance.
Csm in the fiberglass world is Chopped Strand Mat.
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