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May 15, 2007, 05:03 PM
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tim slocum's Avatar
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Help with fiberglass hull needed!!


My predreadnought Missouri BB11 project has been stalled for a while now because of a problem Im having with the hull.I have a fiberglass hull that I am converting for my project.Well,I altered the bow by cutting out a V shaped piece and was going to bring the two side back together.This is hard to describe,I hope you can see what Im trying to do.Anyway,I've tried 2hr epoxy to bond the two sides back together and it failed to hold. Because of the shape of the bow,it's very hard to clamp the to side together.I think Ive overcome this,by drilling a hole and running a bolt through the hull to hold the two sides together.Do you think bondo spot putty would hold?I'd really like to get past this problem and proceed to next one HELP,ADVICE PLEASE!!
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May 15, 2007, 05:13 PM
Where's Pamela?
patmat2350's Avatar
Your hull is likely built with polyester resin (as opposed to the more expensive epoxy)... epoxy glue will only give the appearance of sticking, then Pop! Even after sanding etc.
Use polyester resin as glue, perhaps thickened with talc or microballoons. If the joint is under stress (wants to pop apart), then a mechanical tie may be needed too.

Spot putty ("glazing putty") has zero strength.

Pat M
May 15, 2007, 05:16 PM
Dr John
pmpjohn's Avatar
Epoxy will not stick well to polyester. You will need to sand and scrub with acetone the area you want to stick. Clamp the sides in position and lay in FG cloth and polyester resin 2-3 inches back on both sides of the seam. This will give the strenght of the cloth and a much larger bonding area.

John
May 15, 2007, 05:44 PM
Registered User
Interesting and timely subject since I have recently aquired several polyester hulls that I plan to build out- I am a big fan/user of West System Epoxy so I thought I would go to them to see if West can be used for bonding various parts to poly hulls- I got an emphatic yes!

West pointed to many examples of how their epoxy is used in the repair of polyester boats and in new construction, where hulls may be polyester with the bulkheads bonded in using epoxy/glass... I will be doing some of my own tests over the summer...

If I understand what you are doing Tim, it sounds like there is a lot of "pre load" in the joint you are making and it may require more material to make it work...
May 15, 2007, 06:03 PM
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tim slocum's Avatar
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Would Epoxy finishing resin work? I found a product called Z poxy.It says that its good for bonding fiberglass cloth.Patman,what brand of polyester resin would you suggest and where can I purchase some?Aerominded,yes the area is some "pre load" in the joint.
May 15, 2007, 06:17 PM
Registered User
My comments are only based on what West System says about their product... not sure if all epoxies are the same so I'm not sure about Z poxy... Like I said, I will do some of my own testing to be convinced!

I understand a lot of folks have had good luck bonding motor mounts, stuffing tubes etc to poly hulls using autobody filler... I'm just not sure how well that is suited to doing a neat job of installing decks, etc...
May 15, 2007, 07:01 PM
River Rat
towboatjoe's Avatar
Regular 2 part epoxy you buy in the twin tube will not work. In fact it is not waterproof and will break down after prolonged emersion in water.

Epoxy finishing resin on the other hand is anotr thing and, used with fiberglass mat, will do the necessary job of bonding polyester hulls.

I do all my hulls with epoxy finishing resin and 3/4 oz fiberglass mat. Example of how I do it can be viewed at http://www.towboatjoe.com/hulls.htm

Bondo will work, but talking about serious sanding! That stuff get really hard.
One thing to remember is you can put epoxy over polyester, but you can't put polyester over epoxy. The polyester will go wacko, sometimes it'll crack and split, other times it won't even cure correctly.

In any kind of hull modification or repair you have to sand the area good and use mat to reinforce the resin. Resin alone will not hold.
May 15, 2007, 07:57 PM
"day ain't over yet-"
der kapitan's Avatar
Tim, Aerominded and Towboat Joe are telling it like it is with epoxy and polyester resins, and I don't think I could add much to their input.

I'm not too familiar with West System epoxy, so I can't say if it'll work well or not for you.

However I have used Bondo autobody filler on certain applications as an adhesive for years with very good luck.

Just remember that it is porous, and needs to be sealed with paint to prevent water being absorbed.
May 15, 2007, 08:19 PM
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tim slocum's Avatar
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Thanks everyone, alot of food for thought.Towboatjoe, thanks for the link,very informative,I bookmarked it.Im torn between polyester or epoxy finishing resin.The polyester is stronger,but the epoxy is easier to mix.Do you guys think the epoxy would be strong enough if I use mat.As I mentioned earlier there is tension on the joint.
May 16, 2007, 07:13 AM
"day ain't over yet-"
der kapitan's Avatar
Quote:
Originally Posted by tim slocum
Thanks everyone, alot of food for thought.Towboatjoe, thanks for the link,very informative,I bookmarked it.Im torn between polyester or epoxy finishing resin.The polyester is stronger,but the epoxy is easier to mix.Do you guys think the epoxy would be strong enough if I use mat.As I mentioned earlier there is tension on the joint.
Tim, find a way to take out the tension at all costs, it may save your skin in the long run.
May 16, 2007, 11:18 AM
Sea Dragon-Lover
Umi_Ryuzuki's Avatar
Quote:
Tim, find a way to take out the tension at all costs, it may save your skin in the long run.
You need to repair and attach the pieces together and even "finish" the joint before you fiberglass across the area.

If this takes brass rods, plywood, or other bracing the pieces should be solidly connected before you fiberglass. As far as "finish", the joint should closely resemble the finish you want after fiberglassing. This way you don't spend too much time sanding and glazing the area you are repairing.
May 16, 2007, 10:52 PM
Boats on the brain!!
green-boat's Avatar
Tim,

This is just a thought but epoxy and polyester resins are a plastic. How about applying some heat from a heat gun to soften the plastic to the point where you can get the two halves into position, clamp them together and let them cool. Then you can resin them over to close them up.
May 17, 2007, 07:28 AM
Registered User
killick's Avatar
....Definitely use the "Mat"....! If in doubt at all go with the poly resin and made absolutely certain -- no matter which compound (poly or epoxy resin) you decide to use -- that you have sanded ANY other adhesives off and that you are down to the "original" fibreglass. Make sure the hull cannot "come apart" until it has properly cured. (......"Duct Tape" ??)

Best of Luck--!
Paul.
May 22, 2007, 07:16 PM
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tim slocum's Avatar
Thread OP

Stopped off at Walmart today and got....


Bondo's Fiberglass Repair Kit #420.It includes polyester resin, liq.hardner,fiberglass cloth(what oz?)and a plastic spreader.After the posts I recieved,I decided to go with polyester resin for strength.This will be my first experience with this stuff,but I need to learn about it for future builds on my to do list.Sometime in the next few days I'll try to fix my hull and let you know what happened.Any final words of wisdom for a first time fiberglasser??
Last edited by tim slocum; May 22, 2007 at 07:19 PM. Reason: Too many errors
May 22, 2007, 08:53 PM
Dr John
pmpjohn's Avatar
Carefully measure the resin and hardener and stir stir stir and then stir some more.

John


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