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USA 5184

G-Flex vs. Plexus - ABS plastic boat repair

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Yes yes I know one of these threads again. I am looking for advice from anyone who has repaired cracks on a JY 15, Hunter 170, or Hunter 216. It looks like plexus adhesive is the general consensus, but I see some people mention G – flex and wonder if that would work as well. Is one better than the other? Does one last longer than the other? G-flex by West Systems is an Epoxy, while Plexus is an adhesive. Would the G-flex hurt the foam core? If plexus adhesive is the way to go, which one should I use? The Jamestown distributors website lists a few types of plexus which all seem like they would work well on a Thermoplastic hull. Any advice, insight, or recommendations that you might have will help as well as any long term updates as to how your repair held up over time. 

 

Please don’t ask for pictures or give me a history lesson on which two companies provided the plastic for these boats which is how all of these threads end up. I’m simply looking for advice on which material to use in my repair.

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IIRC, the Gougeons have an article at the site in which they describe chainsawing and then repairing a plastic kayak, includes technique.

 

I used Gflex to repair a PVC flexible furler, and my article is also at the west site. Read and make yer own decision. I can say that the alcohol wipe and flame treatment are important to get good results. 

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That’s the video I saw that led me to believe that G-flex looks too good to be true. I was ready to buy the Plexus but this stuff looks pretty good too. The problem with the flame treatment when repairing a JY15, Hunter 170, or Hunter 216, is they have foam cores that won’t like being touched by an open flame. Too bad, this stuff looks like it’s a cure for damaged solid plastic Kayaks. Also, I’m not sure they are quite the same plastic.

Now in thinking remove some foam core under the dremeled out crack, replace with something that can withstand the flame treatment, then us G-flex. Something to think about. Still looking for others who have repaired one of these boats and their results on how long the repair lasts. 

 

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You’re just waving the flame over the substrate, not setting it on fire. It’s a molecular change effect. If done correctly you shouldn’t be anywhere near catching anything, including foam core, afire 

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I have used both to repair cracks in JY 15s . Go with G Flex or thickened G Flex or you can add thickening powders to it. You should probably paint over it for UV. OMC johnson white matched ok. 

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Posted (edited)

I repaired several serious 5-inch cracks in a ABS paddleboat topside using G-flex last summer.  G-flex was thickened and applied after treatment as described, then I cleaned it and layered on a fiberglass cover using regular West Marine epoxy. It looks fine this summer.  But in the meantime, I left it outdoors all winter standing on edge.  The already - cracked tub- floor sections split badly.  Methinks  this is too extensive to mess with.  Drat!

 

Edited by dacarls
misspelled 'treatment'

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“Ace  plastic repair epoxy” . https://www.millerhardware.com/p-10005-ace-plastic-repair-epoxy-85-oz.aspx?gclid=Cj0KCQjw2f7bBRDVARIsAAwYBBtKPPeRlnF4HD2yMKYtSQlS_aqwydj1aNjbEdy0i8hoHal8lIGE31kaAt_HEALw_wcB

this is the best cheap stuff I found in a dozen repairs. It’s called an epoxy but is not a true epoxy it’s the methyl-??? stuff in plexus. The other brands did not work as well. There are very good diy instructions searchable by “ACP repair Hunter 216” or something like that. I’m on a boat delivery right now but if you private message me with your email address I will get in touch with some follow up info. The repairs are pretty easy, about the same effort as varnishing wood. Lots of short applications, some sanding. When you optimize plan on spending 20 minutes a day for 3 or 4 days per crack. Cracks seem to happen every winter. Bought one cheap, sold it cheap, had fun with it for the time I had it. Did not try G flex, though have used it on epoxy surfboards without a problem.

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https://www.amazon.ca/Devcon-22045-Plastic-Welder-Dev-Tube/dp/B003NUGL9S

 

This is my favorite of the Plexus type adhesives.  I've had some bad luck with similarly labeled ones or "epoxy" labeled ones that actually were a semi-rigid urethane which was bloody useless.   methacrylate is cool stuff, Devcon seems to be about on par with the loctite/plexus 50ML ones for quality at a much lower price.  Wouldn't use it for anything big, but handy for little on the spot jobs.  Strong stuff.  can you add a patch over the cracks or are looks important?  I wonder if you could weld the plastic for real without damaging the core, if it's a regular problem might be worth looking at.  I know the plastic shop near me uses both friction welders and hot air welders. 

 

@USA 5184 If you're going to own the boat a while might be worth looking at a cheap one of either of those, or some jerry rigging.  You can friction weld with a dremel or router(variable speed) and you probably won't get much heat into your core foam, but get a very good bond.  I have never done it myself but want to try it sometime soon.   I've had custom waterproof drawers built from Starboard this way for boats.   

 

 

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It looks like Ace Hardware(US), Devcon, & Loctite all sell a plastic repair epoxy. None of them are epoxy. They are all methacrylate. This is the adhesive in Plexus. I've noticed that some of the brands of concrete tie down epoxy is also falsely labeled. Its also methacrylate.

Its good to know, since Plexus is expensive, hard to come by in AU and every once in awhile methacrylate is a better choice than epoxy or g/flex. They are also small tubes like 5 minute epoxy.

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2 minutes ago, CaptainAhab said:

It looks like Ace Hardware(US), Devcon, & Loctite all sell a plastic repair epoxy. None of them are epoxy. They are all methacrylate. This is the adhesive in Plexus. I've noticed that some of the brands of concrete tie down epoxy is also falsely labeled. Its also methacrylate.

Its good to know, since Plexus is expensive, hard to come by in AU and every once in awhile methacrylate is a better choice than epoxy or g/flex. They are also small tubes like 5 minute epoxy.

Loctite and Plexus both sell professional style 50ML cartridges with mixing nozzles, special gun, special tips.  Not all that handy for a single shot job, I haven't found much difference between them(unless you get into the more viscous plexus ones).  Epoxy is a buzz word in this case, on the shelf depending on brand there can be mixed up "plastic repair" products with both resins, all called epoxy.  Devcon plastic welder is simple, if you find those words, you have the right product.

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In my experience.The devcon and ace brands worked well, the “DO IT Center”  brand never hardened properly.

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Thank you for all the replies. I set out fixing the 3' crack on the cabin top by using the Mini-Weld model 7 airless plastic weld with ASA plastic welding rod (ASA is Luran S, what the boat is made out of). I dremmeled out the crack, heated up the sides of the crack, then melted the plastic rod through the extrusion hole into the crack. It was very simple and came out looking great only to crack again in 3-4 days. I tried again with the airless welder & rod but it cracked again. Next I dremmeled out all of the platic I welded into the crack and used REAL Plexus MA300. I figured if I'm repairing my boat, is $25 really that much more than $5 to get the real thing?

 

So far I am very happy with the result. the Plexus does lose a little volume after it dries so the crack is slightly concave at the moment. I will go back and sand & apply a second layer then paint.

H92.jpg

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