The Hull Truth - Boating and Fishing Forum

Go Back   The Hull Truth - Boating and Fishing Forum > BOATING FORUMS > The Boating Forum
Search

Notices

Random Quote: Remember- Birds do not walk on water!
Reply
 
Thread Tools Search this Thread
Old 05-16-2012, 07:49 AM
  #1    
Junior Member
 
Join Date: May 2012
Posts: 12
Default Layers of fiberglass

I am building a small pontoon boat. I am making the pontoons from Styrofoam and coating them to protect them from moisture and gas. I want to cover them with fiberglass but I am not sure how many layers to go with. The pontoons measure 16 inches square and 6 foot long. I have 4 of them so I can adjust them. I have contacted one person and they recommended 3 layers of 10 oz woven. I am using epoxy resin and vacuum bagging. I want the pontoons to be durable because I will be using the boat for duck hunting and fishing. The pontoons will see some abuse. I would appreciate feedback if 3 layers of 10 oz is enough or should I go more? Less??? Heavier fabric??? There are no complex shapes or tight areas.
Thanks for your time answering.
yroy is offline   Reply With Quote
Old 05-16-2012, 08:21 AM
  #2    
Senior Member
 
Join Date: May 2010
Location: Cape Cod
Posts: 315
Default

You would be better off using a couple layers of chop mat, then your woven in between. That will give it much more thickness and strength. Also do a test patch and make sure your resin will not eat the foam!
__________________
1972 23 Seacraft, Hermco bracket, 250 Honda Birdsall Ttop and Leanpost... a few other goodies too.

http://www.classicseacraft.com/commu...ad.php?t=21924

Honda BF250: because what would you rather have powering your boat a Honda Accord or a Snow machine?
Wildman_fab is offline   Reply With Quote
 
Old 05-16-2012, 08:21 AM
  #3    
Senior Member
 
Join Date: May 2009
Location: Hypoluxo, FL
Posts: 464
Default

10oz woven cloth seems too light. If I was using 90/0 degree fabric, I would use 18 oz woven at a minimum.

My preference would be for biaxial cloth (+45/-45 degree). I would use a couple layers of 1700 biax cloth with a top layer of 1708 biax/mat (has 8 oz mat attached to the 17 oz biax as the top layer) for strength, protection from drops or impacts and light weight with epoxy. You might get by with 2 layers, but if abuse is likely, I would go with 3 layers.

You will need to paint the epoxy to protect it from UV light.

Sounds like a fun project. Good luck!
kgreggfl is offline   Reply With Quote
Old 05-16-2012, 08:45 AM
  #4    
Admirals Club
THT sponsor
 
Join Date: Aug 2011
Location: Beaufort NC
Posts: 2,604
Default

The main problem with styrofoam is it's density isn't very high so crushing and denting is fairly easy and the skin should be thick enough to handle it. Sides would need less protection (hopefully!) but the bottoms should have good abrasion/crush resitance.

10oz woven roving (NOT finish cloth) is a little on the light side nand will leave a very coarse grain requiring more fairing afterwards. 1700 or 1708 would be much better and bulking between layers with chopped mat will help. At a minimum I would use two layers of 1700/1708 with one or two layers of mat somewhere in there and add an extra to the bottom surface wherever it may scrape bottom. You could substitute the 10oz woven but I'd add one extra layer to be on the safe side. As also mentioned the epoxy needs UV protection so plan on some sort of paint/primer.
__________________


Blending classic Carolina looks with modern technology

www.lightningyachts.com
bills106 is offline   Reply With Quote
Old 05-16-2012, 09:14 AM
  #5    
Junior Member
 
Join Date: May 2012
Posts: 12
Default

I coated the foam with styrospray 1000. this protects it from anything that would eat the foam plus the epoxy won't eat the foam. (styrene resins will). The coating also gives the foam a lot more rigidity. It is about the thickness of a dime.
Thanks for your input
Roy
yroy is offline   Reply With Quote
Old 05-16-2012, 09:21 AM
  #6    
Senior Member
 
Join Date: Jan 2010
Posts: 2,873
Default

Quote:
Originally Posted by yroy View Post
I coated the foam with styrospray 1000. this protects it from anything that would eat the foam plus the epoxy won't eat the foam. (styrene resins will). The coating also gives the foam a lot more rigidity. It is about the thickness of a dime.
Thanks for your input
Roy
Isn't Styrospray a type of plastic? You may have a tough time bonding the resin to this coating......I would do a test panel first.......the only marine epoxy I know of that may stick to plastic is West System G-Flex
maxie is offline   Reply With Quote
Old 05-16-2012, 09:21 AM
  #7    
Junior Member
 
Join Date: May 2012
Posts: 12
Default

I was afraid the 3 layers of 10 oz would be to thin. That only adds up to about .033 thickness plus whatever the epoxy adds. Is there any problems with vacuum bagging 3 layers plus a layer or 2 of the matt?
yroy is offline   Reply With Quote
Old 05-16-2012, 09:24 AM
  #8    
Junior Member
 
Join Date: May 2012
Posts: 12
Default

According to the manufacture the epoxy will bond to it and is recommended if you are using styrofoam. it better or i am screwed on a lot of work.
yroy is offline   Reply With Quote
Old 05-16-2012, 10:16 AM
  #9    
Senior Member
 
Join Date: May 2009
Location: Hypoluxo, FL
Posts: 464
Default

Laminating 10oz woven with a couple layers of mat doesn't really give you any added strength or stiffness. You add thickness and weight, but no real improvement in strength. Why go to the trouble to vacuum bag with epoxy to give up those gains by adding bulk and weight with mat? Mat can give you more surface area contact between the bonding surface and 1st layer of woven (or between layers of woven) and can also give you a smoother finished surface on the outer layer (less filling and fairing). One of the benefts of the biax is the strands don't cross, so no leverage is exerted across the strands on the resin/glass when a load is applied. You get high strength with low weight. On woven, each strand is crossed in the weave, so woven layups end up being more brittle than biax or triax layups Using biax would be more consistent with the benefits of vaccum bagging.

Epoxy bonds to some plastics. I know it bonds to PVC pretty well, but I havn't used styrospray before. As Maxie recommends above, I have used West System G/flex on some plastics. It also bonds with other hard to bond materials like damp or oily wood. G/flex is not as structurally strong as laminating or bonding epoxies, but it is compatible with other epoxies. You could hotcoat the surface of the styrospray with G/flex and laminate over it with your layup, if you were really worried about the styrospray/bonding. If your epoxy mfr says it will bond, I would think it would work.
kgreggfl is offline   Reply With Quote
Old 05-16-2012, 11:46 AM
  #10    
Senior Member
 
Join Date: Jan 2010
Posts: 2,873
Default

Depending on where you buy your cloth (and make sure if it has chop in it, its compatible with epoxy), the cost diference between say an 18oz roving at $8 per yard and 1708 at $10 per yard, won't kill your wallet too bad.....the biax will lay down nicely under the bag...4 or 5 layers will get you around 1/4 inch in thickness, so 3 layers you'll be just over 1/8 under pressure.

I would still do a test panel with the styrospray and see if you get substrate delamination......clean it with solvent, sand it up well, clean it again and bond some glass...try and destroy it......it would suck, big time, to do all that laminating just to have it pop off down the road sometime.

Question, aren't surfboards made from styrofoam? What do builders use for bonding and resin when making them??
maxie is offline   Reply With Quote
Old 05-16-2012, 01:26 PM
  #11    
Admirals Club
THT sponsor
 
Join Date: Aug 2011
Location: Beaufort NC
Posts: 2,604
Default

Quote:
Originally Posted by maxie View Post
Depending on where you buy your cloth (and make sure if it has chop in it, its compatible with epoxy)
Chopped strand mat while compatible with epoxy isn't required unless you are looking to bulk up the stack and/or trying to minimize print through, which it only helps just slightly with non post cured epoxy. According to an engineer who worked with Knytex developing it, they were looking for a material to interface between polyester resin/fiber matrix and substrates like plywood that would act like a cushion to minimize the different materials flexural characteristics and bridge the gap between the two since polyester didn't penetrate the wood very well if at all. Polyester being very rigid and wood more flexible, they had a lot of shear resulting in delamination in the early days and mat was the solution they came up with.

Epoxy is much more elastic and penetrates the wood "plasticizing" the outer fibers so the risk of delaminnation is extremely minimal with proper layup and most of the more advanced epoxy builders have dropped it completely in favor of an extra layer of biax reinforcement which in the case of 1700 weight cloth is equal in wet-out weight to a layer of non-structural mat.
__________________


Blending classic Carolina looks with modern technology

www.lightningyachts.com
bills106 is offline   Reply With Quote
Old 05-16-2012, 01:52 PM
  #12    
Senior Member
 
Join Date: Jan 2010
Posts: 2,873
Default

Quote:
Originally Posted by bills106 View Post
Chopped strand mat while compatible with epoxy isn't required unless you are looking to bulk up the stack and/or trying to minimize print through, which it only helps just slightly with non post cured epoxy. According to an engineer who worked with Knytex developing it, they were looking for a material to interface between polyester resin/fiber matrix and substrates like plywood that would act like a cushion to minimize the different materials flexural characteristics and bridge the gap between the two since polyester didn't penetrate the wood very well if at all. Polyester being very rigid and wood more flexible, they had a lot of shear resulting in delamination in the early days and mat was the solution they came up with.

Epoxy is much more elastic and penetrates the wood "plasticizing" the outer fibers so the risk of delaminnation is extremely minimal with proper layup and most of the more advanced epoxy builders have dropped it completely in favor of an extra layer of biax reinforcement which in the case of 1700 weight cloth is equal in wet-out weight to a layer of non-structural mat.
Interesting and excellent Info on the chop/PE/wood combination....thanks very much..
maxie is offline   Reply With Quote
Old 05-16-2012, 05:18 PM
  #13    
Junior Member
 
Join Date: May 2012
Posts: 12
Default

I am going to test a small piece tonight of epoxy and the styrolfil 1000. Since the pontoon will be completely enclosed by the fiberglass I will just have to add more layers for strength and the foam will be there to fill the space. I will probably go with the biax. From prior research the biax was a better choice for infusion and the strands were stronger because they didn't bend around the other strands leaving a shear point. I appriciate all the input and thank all of you for responding so quickly. I will let you know if the epoxy bonds to the styrofill 1000
yroy is offline   Reply With Quote
Old 05-16-2012, 05:37 PM
  #14    
Senior Member
 
Join Date: Feb 2010
Location: Ponte Vedra Bch FL
Posts: 107
Default

Yroy, are you going to infuse this or hand lay? I ask because with infusion, there are certain advantages to using 1708 and woven together w/o mat.
Buddy Barnes Marine Svc is offline   Reply With Quote
Old 05-16-2012, 05:38 PM
  #15    
Admirals Club
 
Join Date: Dec 2010
Posts: 467
Default

Please post some pics, I love little projects like this. I regularly work little projects with epoxy and glass, two days ago I laminated three, 8x12 inch layers of 3/4" marine ply than "jerry" bagged two layers of 1708 (clothes storage vacuum bag and shop vac), the two layers gave close to 1/10" fiberglass thickness.
__________________
Chris Craft Commander 333/ 454 Crusaders
Saturn 14ft inflatable/40hp Tohatsu
15 foot Jon boat/25 Evinrude
chris commander is offline   Reply With Quote
Old 05-16-2012, 07:58 PM
  #16    
Senior Member
 
Join Date: Apr 2006
Posts: 2,233
Default

Seems like there are a few knowledgeable guys on this thread. Would you consider using a layer of Kevlar to provide the protection against 'dents' and penetration? We built some sailing dinghys for competitive racing with foam decks years ago and put Kevlar on the side decks where our butts and feet went. Wasn't my design, but it worked really well.
Aliboy is offline   Reply With Quote
Old 05-16-2012, 08:07 PM
  #17    
Senior Member
 
Join Date: Feb 2007
Location: North Palm Beach, FL
Posts: 5,335
Default

If you bag this project, you will have a lot of fairing and finish work to do. Depending on the vacuum pressure you reach, you could deform the foam in odd spots. It really isn't necessary to bag this type of project. As for the compatibility of the Styrofill and the epoxy, I wouldn't worry about it too much. The foam will help to support the laminate but it is not what is really considered structural. That is to say, it wouldn't make a whole bunch of difference if the epoxy bonds or not. The styrofoam substrate is not strong enough to withstand much shear (the laminate can be readily peeled off).

I would personally hand laminate two layers of 1708 if I was concerned about weight. Three layers if I was more concerned about toughness.
__________________
Disclaimer: If you see emoticons, that means the above is written in jest. It is for entertainment purposes only. It is not meant to represent any actual persons, places, or things. It is the opinion of the poster that it is funny. Your opinion may vary. No animals were harmed in the typing of this post but a few egos may have been bruised.

Last edited by OReely; 05-17-2012 at 07:05 AM. Reason: meant three, not the in last sentence
OReely is offline   Reply With Quote
Old 05-16-2012, 09:58 PM
  #18    
Junior Member
 
Join Date: May 2012
Posts: 12
Default

I was thinking about kevlar tape on the edges that will take a lot of abuse.
yroy is offline   Reply With Quote
Old 05-16-2012, 10:07 PM
  #19    
Junior Member
 
Join Date: May 2012
Posts: 12
Default

Quote:
Originally Posted by OReely View Post
If you bag this project, you will have a lot of fairing and finish work to do. Depending on the vacuum pressure you reach, you could deform the foam in odd spots. It really isn't necessary to bag this type of project. As for the compatibility of the Styrofill and the epoxy, I wouldn't worry about it too much. The foam will help to support the laminate but it is not what is really considered structural. That is to say, it wouldn't make a whole bunch of difference if the epoxy bonds or not. The styrofoam substrate is not strong enough to withstand much shear (the laminate can be readily peeled off).

I would personally hand laminate two layers of 1708 if I was concerned about weight. The layers if I was more concerned about toughness.
I thought the bagging would do a much more quality and uniform job then what I would do since I woke up one morning and decided to build a little different simple pontoon boat. I can't afford 2 boats and I have a 20 foot duck boat that sits 9 months out of the year. I am suprised how rigid the styrofoam is with the styrofill 1000 on it. I really like it. I don't think the pontoon will move while I vacuum bag it.
yroy is offline   Reply With Quote
Old 05-16-2012, 10:17 PM
  #20    
Junior Member
 
Join Date: May 2012
Posts: 12
Default

Quote:
Originally Posted by Buddy Barnes Marine Svc View Post
Yroy, are you going to infuse this or hand lay? I ask because with infusion, there are certain advantages to using 1708 and woven together w/o mat.
I am going to infuse. I am nervous about where and how many feed lines to hook up. I need to ask about vacuum pumps. I have a 3-4cfm THOMAS VACUUM PUMP 22-24"hg // air pump, does it sound like this will dot the trick. size of block 16"x 16" x 6 ft
yroy is offline   Reply With Quote
 
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 



©2009 TheHullTruth.com

Powered by vBulletin® Version 3.7.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.2.0