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Question about Fiberglaass layup

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Old 08-07-2009, 01:52 AM
  #1
FineDesigns_1
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Default Question about Fiberglaass layup

Hello, I just bought a mold for a 47" v-hull. I'm thinking 4 layers,

Layer 1 2.3 oz cloth (Outter most layer)
Layer 2 6 oz cloth
Layer 3 1.5 oz mat
Layer 4 2.3 oz cloth (Inner most layer)

With the transom and stringers glassed in with 1.5 mat and then 2.3 cloth

Will this work, or does someone have a better idea ?


Thanks,
Tim
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Old 08-07-2009, 03:04 AM
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Default RE: Question about Fiberglaass layup

Are you going to use Gel-coat?
I assume yes, then you don't want cloth as your first layer as you can get print through from the cloth to your gel coat. Next you don't want cloth on cloth, the cross pattern allows too many gaps for air bubbles to get trapped in. One layer of cloth is weeker than equal layer of matt, cloth only gets strong if you lay a second layer at 45* to the first. It looks nicer as a finish layer but that is it.
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Old 08-07-2009, 03:42 AM
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Default RE: Question about Fiberglaass layup


Quote:
ORIGINAL: FineDesigns_1

Hello, I just bought a mold for a 47" v-hull. I'm thinking 4 layers,

Layer 1 2.3 oz cloth (Outter most layer)
Layer 2 6 oz cloth
Layer 3 1.5 oz mat
Layer 4 2.3 oz cloth (Inner most layer)

With the transom and stringers glassed in with 1.5 mat and then 2.3 cloth

Will this work, or does someone have a better idea ?


Thanks,
Tim
Congrats on getting a mold. Most boats in this size only use 2 layers of glass, if that depending on the manufacturer. Your going to have a very heavy boat using the layup you describe. More importantly all your layers should be applied at the same time using the same batch of resin. No way will you have enough time to tool in all thoes layers before your resin kicks off. You will be using way too much resin since the first layers won't be able to wick into the latter layers fusing them all together in time in one application.

All my boats are glassed up using a gelcoat layer, applied with a gelcoat gun and not thinned down. Followed by one layer of .75 mat directly over the gel layer. Finally a layer of 6oz "S" glass cloth. I've experimented with many different layups and found that the one I just described offers the best strength and lowest weight for my mono and catamaran designs. The S glass cloth is slightly different than the standard "E" glass cloth in that it gives about 25% more strength and wets out significantly easier using laminating resin. By the way, don't use that crap resin that Bondo makes, it's not for laminating. You will need a good quality laminating resin.

On my website, I've included a very detailed step by step guide on how to accomplish this on a mono. Your hull should be very similiar.

firststatecomposites.com/howitsdone_.html

I've altered a couple things in the process since that page was made, just need to update a little I suppose. The main thing is I no longer use PVA. Just a good brand of mold wax. Parts have been floating out of the molds nicely using just good blast of air pressure from my compresser. Good luck and please ask away whatever questions you may have.

By the way, Iwoulden't suggest using just mat in your layup. I've done this a few times and "drop" tested a couple hulls using only mat and found that it does make a easy to lay up hull, however the strength is definately not there. Mat is a build layer while the cloth gives it strength against impact. Using thoes 2 layers mentioned above will create a very strong and lightweight hull that is easy to layup.
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Old 08-07-2009, 10:09 AM
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Default RE: Question about Fiberglaass layup

Wow, That web site will be a big help Dreamin, thank you very much. Maybe I'll start a post and keep track of my progress.

Thanks for all the help,
Tim
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Old 08-08-2009, 02:19 AM
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Default RE: Question about Fiberglaass layup

Cloth can't handle the high frequency vibrations and will break down quicker than mat. Andy (AC) uses 4 layers of mat, good enough for him good enough for me.
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Old 08-08-2009, 03:02 AM
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Default RE: Question about Fiberglaass layup


Quote:
ORIGINAL: MrMikeG

Cloth can't handle the high frequency vibrations and will break down quicker than mat. Andy (AC) uses 4 layers of mat, good enough for him good enough for me.
I agree i use matt on all my boats and all hold up to the job in fact i had a t boat i made crash the other weak with minimal damage to the hull even though the motor broke its mounts on impact.Someone i know did a similar thing with an aeromarine avenger a cpl of years ago and the whole front end was a right off,i believe they use cloth in the layup.That should give you a good indication of how strong matt can be.Cloth looks nicer but unless you go for a more expensive multi weave cloth or as Mike says lay the next layer at 45% to the first im not so sure its stronger.Ive been doing 3 layers of matt of late and the hulls come out light and strong.On my last hull i used 600 csm and split it into 3 layers the first been very thin then i layed the others directly on top using the same batch of resin,you need to work fast and it takes practice to get the process right.Sometimes i lay a thin layer of cloth on top just to please the eye.This made for a very light hull but very strong,i know of a company who use one layer of 600 in one go which i wouldnt advise as its very thick and hard to wet out and get into contours and corners etc.Oh ive also dropped a cpl of hulls and had no structural damage apart from a cpl of scratches so i supose that counts as a drop test .
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Old 08-09-2009, 02:50 AM
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Default RE: Question about Fiberglaass layup

Andy loads up his pick-up with a couple of hulls, goes to Kmart after closing, lines up a concrete light pole, gets going 35 mph and throws the hull nose first into the concrete pole. That's his "Drop test". For the High frequency vibration he lays up panels of glass the same thickness he would use in his hulls, jacks up the rear of his tractor, starts it up, gets the wheels turning and clamps the panel to a saw-horse and pushes it into the tractor tread a set distance.
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Old 08-09-2009, 10:49 AM
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Default RE: Question about Fiberglaass layup

Not sure how a tractor tire could possibly adminster the "high frequencies" generated that a gas engine delivers at 12,000+ rpm. Suppose I should have stated this "drop" test that appears to be of interest. Taking one of my older hulls RTR so full weight slammed into rocks, ran over by full scale boats while operating (oops), run into banks (more like launched into the air landing upside down 20 feet away). All extreme real world type torchure tests have not showed signs of fracture or delamination, just gelcoat chips and paint scratches. So yeah, I'll toot my own horn and back up the way I choose to do things.

Never said mat wasnot good to use, but try to tear one layer of mat withhardened resin, then try the same tear with cloth. I guarantee you won't be able to tear the cloth.The way I do things are based on several things including multiple tries at different layups with my students at a tech school.Probably150 tests eachsemester with students trying different layups testing for strength and weight using pressuretesting machines in the lab/shop. Most my professional reasons for doing the way I do comes from real world tests and utilizing my degrees in structures engineering and technical education. Forgot to mention the experiences I've had working with fiberglass and body shops to allow me to fund my college education......but what do Iknow . To each his own.


Mart: Just FYI, separating a single mat layer "3 times" will not make your laminate any stronger than applyingthat layer atone time. It's already random in pattern. You'll justprobably use more resin. Been there, tested that theory probably ay least ahundred times or more with my students.
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Old 08-09-2009, 11:18 AM
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Default RE: Question about Fiberglaass layup

Thing is Scott it does come across as you are saying mat is not good enough but as ive allways said to you for model boat manufacturing its perfectly fine to use.The AC boats are some of the best boats in the world as regards reputation so if its good enough for them its good enough for me.I know splitting my mat into 3 wont make it stronger i never said it would i was just saying how i did the last one.Seeing as its what i had left i used it and it makes life easier to use it in thinner layers rather than one thick layer.I didnt use any more resin either i used arround the same amount.Some of the weakest boats ive seen are made from 4 layers of cloth and no matt ,theyre paper thin and weak as well i cant say the word here.I can say theyre made in China [X(].
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