Epoxy won't stick

[zooma]

This is my first experience with a carbon fiber hull. It is a TFL Ariane 2. On the second run, it flipped, and the CF battery tray popped loose. When I glued it back in, I used Great Planes 30 minute epoxy with some West Systems milled fibers. Next time out, I hit an inflatable club buoy, and the tray popped out again. So, a club member tells me that you can't use epoxy on carbon fiber, you have to use fiberglass resin. I thought he meant polyester resin. On the other hand, the popular West Systems 105 resin is labeled epoxy, not polyester.

Now I am lost. I have been using hobby grade slow and fast epoxies on my fiberglass hulls, even after collision repairs.

Any suggestions?

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[properchopper]

I've not seen that particular hull, but I've seen others from that company that in CF are fairly thin and will flex in use. You'll need a bonding agent that will stick to CF (well scuffed and clean) and allow for some flexing. This stuff fits the bill : it's SERIOUSLY strong, sticks to everything and totally flexible as well (it held my 60 year old 40 foot vintage motor yacht together ). 48 hour tack; 7 day to full cure. (Don't get on fingers). Others use aquarium silicone which I suspect is molecularly similar...

DSC06912.JPG

[ray schrauwen]

That will work and so will Marine GOOP.

[T.S.Davis]

E6000 adhesive is forever.

Most carbon plate is epoxy and a carbon fiber cloth. The cloth is saturated with the two part epoxy resin. There may be some that are saturated with catalyzed polyester resin but that would be rare. After cure you have a fiber reinforced plastic (FRP).

Once the FRP's (hull and the plate) are fully cured you can only join them mechanically. If you could attach them during the cure they become atached chemically and are a single matrix. When joining mechanically, the epoxy basically has to grab hold of both plate and hull. If there is any grease, wax, heck even body oil, there is a risk that the epoxy can't hold on. The risk increases if the boat is polyester resin and the plate is epoxy resin. You can still use epoxy. You just have to scuff up both surfaces well and then clean with acetone or some other solvent prior to applying the epoxy. That's what I usually do but depends on the boat.

The goop, aquarium sealant, and E6000 have enough flexibility and adhesion that they can cling on through almost anything. They just don't provide as much reinforcement as epoxy and some additional cloth etc. You're not always after reinforcement though.

[Ken Haines]

Like Tony Mentioned the 5200 works well, and even comes in Black which looks great against the CF.
It is incredibly strong and a bit flexible too. If applied carefully using a smaller opening in the applicator nozzle
and setting your boat or glue surfaces level it will cure to a perfect fillet bead. Being black against the carbon fiber
plates and mat that I have used it on actually dressed up the rough edges in addition to the high strength.

[Doby]

I've built 4 boats from P size to T size with Marine Goop...I'll never use anything else again.

[TRUCKPULL]

Like Tony Mentioned the 5200 works well, and even comes in Black which looks great against the CF.
It is incredibly strong and a bit flexible too. If applied carefully using a smaller opening in the applicator nozzle
and setting your boat or glue surfaces level it will cure to a perfect fillet bead. Being black against the carbon fiber
plates and mat that I have used it on actually dressed up the rough edges in addition to the high strength.

You can also use 4200, it comes in different colors also.

Larry

[z400]

Black silicone also works.


Doesnt have to be black but it looks a bit better then the clear or white glue.

[dmitry100]

Hmmm! Yea, that's probably the reason why no one ever uses epoxy for battery trays... you want something elastic like the black aquarium sealant like someone has mentioned but not brittle like epoxy! www.Keithbradleyboats.com has it on their site to buy. Check it out.

How well did you sand all the joints anyway? Especially that glossy CF battery tray... definitely won't hold without sanding it super well.
Maybe use some bigger grit ... you need to give epoxy some grip by sanding it really well.

[zooma]

Hmmm! Yea, that's probably the reason why no one ever uses epoxy for battery trays... you want something elastic like the black aquarium sealant like someone has mentioned but not brittle like epoxy! www.Keithbradleyboats.com has it on their site to buy. Check it out.

How well did you sand all the joints anyway? Especially that glossy CF battery tray... definitely won't hold without sanding it super well.
Maybe use some bigger grit ... you need to give epoxy some grip by sanding it really well.

Well, it came attached with something brittle and white, and definitely not enough coverage. I could not get it off, so just roughed it a little. Of course, now it has lots of cured epoxy on the tray and in the hull. (see picture above). There are lots of build threads, and nobody has mentioned using sealer instead of epoxy. I can probably grind the old stuff off the tray. But, if I take a Dremel tool to the hull, one slip and I'm sunk. I may resort to the 3M 5200

What are people using for their motor mounting rails?

[zooma]

I've not seen that particular hull, but I've seen others from that company that in CF are fairly thin and will flex in use. You'll need a bonding agent that will stick to CF (well scuffed and clean) and allow for some flexing. This stuff fits the bill : it's SERIOUSLY strong, sticks to everything and totally flexible as well (it held my 60 year old 40 foot vintage motor yacht together ). 48 hour tack; 7 day to full cure. (Don't get on fingers). Others use aquarium silicone which I suspect is molecularly similar...

[ATTACH=CONFIG]137018[/ATTACH]

Yeah, I know the 5200 from my boating daze. Also, I once glued a spoiler back onto a car trunk lid, after the screws rusted away.

[properchopper]

Hmmm! Yea, that's probably the reason why no one ever uses epoxy for battery trays... you want something elastic like the black aquarium sealant like someone has mentioned but not brittle like epoxy! www.Keithbradleyboats.com has it on their site to buy. Check it out.

How well did you sand all the joints anyway? Especially that glossy CF battery tray... definitely won't hold without sanding it super well.
Maybe use some bigger grit ... you need to give epoxy some grip by sanding it really well.

a rather imaginative (but irresponsible) statement. "No one ever" - really ?

Use of a premium epoxy like GFlex has been the norm for years and years when bonding trays/rails/internals particularly for racing (where you'll rarely see a CF hull since they're nigh on invisible on the course especially when dead/inverted and present a dangerous navigation hazard or traction opportunity depending on your pit spotter's attention span)

The thin CF hull that the OP started this thread about about presumably flexes too much for epoxy so a bonding product with a flex agent like aquarium silicone or 3M5200 would be advised in these cases.

[Doby]

What are people using for their motor mounting rails?

Marine Goop.

[Chilli]

JB Weld...