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20-02-2014, 17:57
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#1
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Senior Cruiser
Join Date: Oct 2008
Location: Coos Bay, Oregon
Boat: Valiant 40 (1975)
Posts: 4,073
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Welding fiberglass.
I have got a weird one. I have just recently became aware of welding for plastics. Various plastics, including HDPE, can be welded by a heat source and rod material. Well, our boats are really just plastic, and a lot of it. So- Can our boats be welded back together instead of glued with epoxy? I have done internet searches on this and found nothing about welding fiberglass. Has anyone tried this?
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20-02-2014, 18:08
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#2
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Registered User
Join Date: Feb 2012
Posts: 2,441
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Re: Welding fiberglass.
AFAIK the only plastics which can be welded are thermoplastics, not thermo-set plastics and definitely not catalysed resin-set, reinforced plastics.
However it's not my field, so hopefully someone else will clarify.
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20-02-2014, 18:13
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#3
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Moderator
Join Date: May 2008
Location: cruising SW Pacific
Boat: Jon Sayer 1-off 46 ft fract rig sloop strip plank in W Red Cedar
Posts: 21,184
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Re: Welding fiberglass.
Newt, I fear that Andrew is correct -- a little experiment with some scrap FRP and a heat source will likely convince you of this unfortunate fact!
Jim
__________________
Jim and Ann s/v Insatiable II, lying Port Cygnet Tasmania once again.
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20-02-2014, 18:21
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#4
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Senior Cruiser
Join Date: Oct 2008
Location: Coos Bay, Oregon
Boat: Valiant 40 (1975)
Posts: 4,073
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Re: Welding fiberglass.
Most Polyesters (which fiberglass is commonly made of) are thermoplastic. I don't know if our Polyester yachts are (which is why I am asking the question)
Polyester - Wikipedia, the free encyclopedia
I did the basic homework on this one- I just need to know what type of polyester resin is in fiberglass.
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20-02-2014, 18:22
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#5
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Writing Full-Time Since 2014
Join Date: Nov 2008
Location: Deale, MD
Boat: PDQ Altair, 32/34
Posts: 9,601
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Re: Welding fiberglass.
No. Andrew said it all. Neither polyester not epoxy resin melt; they burn.
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20-02-2014, 18:22
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#6
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Marine Service Provider
Join Date: Nov 2008
Location: Port Credit, Ontario or Bahamas
Boat: Benford 38 Fantail Cruiser
Posts: 7,101
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Re: Welding fiberglass.
Google search on "ultrasonic welding polyester"
Just for fun ......
Google "self healing polyester resin"
__________________
If you're not laughing, you're not doin' it right.
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20-02-2014, 18:23
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#7
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Senior Cruiser
Join Date: Oct 2007
Location: 29° 49.16’ N 82° 25.82’ W
Boat: Pearson 422
Posts: 16,306
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Re: Welding fiberglass.
As said, doesn't work for FG. Wrong kind of chemistry. Fiberglass resins set by a chemical reaction and once cured the process cannot be reversed. Plastics like PE, PP and others are polymers that can be melted and worked without changing their molecular structure so can be remelted and welded together.
__________________
The water is always bluer on the other side of the ocean.
Sometimes it's necessary to state the obvious for the benefit of the oblivious.
Rust is the poor man's Loctite.
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20-02-2014, 18:24
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#8
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Registered User
Join Date: Jan 2008
Location: Kingston, ON
Boat: Albin Vega 27'
Posts: 530
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Re: Welding fiberglass.
Never heard of it either. Since FG gets most of it's strength from the glass fibers and the resin helps to bond it together, I'm not sure how it would be able to be welded. But brighter people than me have figured out a lot of things.
__________________
Glenn
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20-02-2014, 18:34
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#9
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Resin Head
Join Date: Aug 2007
Location: Seattle WA
Boat: Nauticat
Posts: 7,205
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Re: Welding fiberglass.
Yes, welding for fiberglass exists. It's called Plexus.
__________________
O you who turn the wheel and look to windward,
Consider Phlebas, who was once handsome and tall as you.
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20-02-2014, 18:34
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#10
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Senior Cruiser
Join Date: Oct 2008
Location: Coos Bay, Oregon
Boat: Valiant 40 (1975)
Posts: 4,073
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Re: Welding fiberglass.
Fair enough. I have learned something about plastics tonight. I have sailed a HDPE cat before. Just a Hobie but lots of fun. I wonder why it hasn't been used for larger boats. Works for milk bottles.
OK- my impressions of the material- very tough, but probably a magnet for marine growth.
It was great for a beach cat, and it didn't seem to be slower than the FG Hobie's running around.
Anybody make a boat of HDPE? (this comes from the guy that wanted to make a Nickel hull a while back )
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21-02-2014, 05:33
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#11
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One of Those
Join Date: Sep 2006
Location: Colorado
Boat: Catalac 12M (sold)
Posts: 3,218
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Re: Welding fiberglass.
I just used a version of this for my own benefit. I stupidly broke off two plastic "ears" from the rear hatch interior door panel of a KIA Sportage. I was fixing the rear washer hose, blah blah. Anyhow, I tried regluing it with plastic cement, no go. Tried epoxy. Nope. Tried contact cement. No luck. Then suddenly I realized nothing was sticking to this just like the ABS I use in my 3-D printer.
So I clipped off about a foot of the 3mm back filament the printer uses, put the flat tip on the soldering gun, and just welded the pieces back on to the big panel. Dang if it didn't work beautifully.
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21-02-2014, 11:13
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#12
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Moderator Emeritus
Join Date: Aug 2005
Location: Carlsbad, CA
Boat: 1976 Sabre 28-2
Posts: 7,505
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Re: Welding fiberglass.
A big problem with welding FRP layup, if it was possible, is the break in continuity of the fibers. The strength in FRP is the fiberglass cloth/matt. If you butt the boundaries between the glass, the butt will be a weak point as the glass strands won't overlap the butt joint. Repairs to FRP layups involve multiple layers of cloth/matt that bond to a large surface area of intact layup on either side of section needing repair. You wouldn't get that with a butt weld.
__________________
Peter O.
'Ae'a, Pearson 35
'Ms American Pie', Sabre 28 Mark II
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21-02-2014, 12:42
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#13
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Senior Cruiser
Join Date: Oct 2008
Location: Coos Bay, Oregon
Boat: Valiant 40 (1975)
Posts: 4,073
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Re: Welding fiberglass.
I would agree with all the above, just sometimes welding is useful. The guys that weld Polyethylene sometimes inbed a stainless mat for the same effect. It would be nice if I could weld my tanks to the hull, even if they were easy to remove the same way. I am going to look at making a HDPE dingy. It would be light and very tough. I think that is what the Portland Pug is made out of. I don't know if I have ever seen a HDPE boat with a hole in it.
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21-02-2014, 13:11
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#14
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Registered User
Join Date: Apr 2011
Location: Sacramento, California
Boat: Solar 40ft Cat :)
Posts: 1,522
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Re: Welding fiberglass.
Quote:
Originally Posted by s/v Beth
I would agree with all the above, just sometimes welding is useful. The guys that weld Polyethylene sometimes inbed a stainless mat for the same effect. It would be nice if I could weld my tanks to the hull, even if they were easy to remove the same way. I am going to look at making a HDPE dingy. It would be light and very tough. I think that is what the Portland Pug is made out of. I don't know if I have ever seen a HDPE boat with a hole in it.
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HDPE is relatively heavy compared to other materials.
This dude has made a river jetboat from HDPE:
see the details in the boat design thread.
I've been working on my cat dinghy, and have starting looking making an LDPE inflatable, and maybe even an inflatable LDPE 40ft cataraman.
LDPE is softer and easier to weld.
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21-02-2014, 17:27
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#15
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Resin Head
Join Date: Aug 2007
Location: Seattle WA
Boat: Nauticat
Posts: 7,205
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Re: Welding fiberglass.
Quote:
Originally Posted by s/v Beth
I would agree with all the above, just sometimes welding is useful. The guys that weld Polyethylene sometimes inbed a stainless mat for the same effect. It would be nice if I could weld my tanks to the hull, even if they were easy to remove the same way. I am going to look at making a HDPE dingy. It would be light and very tough. I think that is what the Portland Pug is made out of. I don't know if I have ever seen a HDPE boat with a hole in it.
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Walker Bay, about the most common dinghy around, are made of plastic. High Impact Polyethylene, IIRC....
__________________
O you who turn the wheel and look to windward,
Consider Phlebas, who was once handsome and tall as you.
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