Damaged sponson tips in crash... Best way to repair it?

[dmitry100]

I'll definitely consider the chopped fibers... that's a great idea. Thanks!

By the way, what should I use to make the pointy ends of the sponson? Perhaps FG milling + zpoxy and then wait a 5-10 mins right before its sets to shape the pointy ends better ?

What kind of GFlex would work? I'm planning to buy some for another hull for glueing mounts etc.
I do have JB Weld though... maybe I should use it with some black pigment for the seams?

[tlandauer]

Make sure you use Zpoxy Finishing epoxy. That's the one to sand and shape. The Zpoxy regular epoxy is for structural bonding, very hard to sand and shape.
Cheers, good luck with the repair.

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[ray schrauwen]

I just learned something... I had no idea the made two kinds. Is the regular structural type slow setting or does it set in an hour like the finishing resin I've used?

Make sure you use Zpoxy Finishing epoxy. That's the one to sand and shape. The Zpoxy regular epoxy is for structural bonding, very hard to sand and shape.
Cheers, good luck with the repair.

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[tlandauer]

I just learned something... I had no idea the made two kinds. Is the regular structural type slow setting or does it set in an hour like the finishing resin I've used?

I use the 30 min. Epoxy from Zpoxy. Part no.39.
Finishing poxy is part 40
Pot life is shorter than Finishing epoxy, like 15 min.

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[T.S.Davis]

I so wish folks would stop encouraging the use of great stuff. Should call it the "wrong stuff". Adds no strength. Doesn't fully cure. I'm not even sure it floats if it doesn't cure. Might not have shattered with 2 part urethane. It's an ancient debate that dates back as long as I've been racing.

Some good advise thus far. I would do the same as Cornel. Clean the GS out of there the best you can. Tack the gaps closed with as little CA as you can get away with. Then tape any holes closed that you can with scotch tape or even hatch tape. Then work the inside.

I use all West Systems but there are other quality epoxies. Just don't fall for the cheap stuff. My experience withe cheap stuff is that it's just that........cheap stuff. Not to be confused with just inexpensive.

I actually have can of graphite powder that I use some times. I make a slurry and apply accordingly. Still wont make it strong that way though. Getting up in that sponson to lay cloth is going to be a bugger. That's really the only way to get any strength back so worth it. A lighter cloth is the only way you'll get it to conform to the angles. Maybe the slurry then some cloth.

Good luck man. Piece it together, paint the tips, send er' back into battle. You aren't the first and wont be the last.

[dmitry100]

Is the 2 part urethane pretty light though?
Always thought foam like that would add a lot of weight to it... but I suppose the added strength would be a good thing.
Do you guys normally do inlay that entire front-end area-- all the way to the tips?

TS Davis: What kind of west systems is good to use for mounts and inlay work? I was thinking to get some GFlex... that seems pricey though for what it is.

[T.S.Davis]

TS Davis: What kind of west systems is good to use for mounts and inlay work? I was thinking to get some GFlex... that seems pricey though for what it is.

I use West 105 Resin. Then there are multiple hardeners depending on what I'm trying to do. 205 is fast, 206 is slow, and 207 is special clear. The longer the cure the stronger the bond. Even 205 takes hours to fully cure though.

Speaking of bond. Some reading for those that don't already know this..... Those that do can stop reading. haha

When fiberglass or carbon fiber are laid, what is being constructed is a fiber reinforced plastic (FRP). The resin is the matrix and the fiber is the reinforcement. The resin cures and becomes one thing. It's a chemical bond but it's basically just a plastic. The strength comes from what is in the plastic. Extra plastic (resin) doesn't add any strength. It's actually kind of brittle on it's own. This is why the best layups are vacuum bagged. That process basically sucks out every drip of extra resin. You're left with just enough plastic to hold the fiber together.

Once the resin is completely cured you can no longer add to the FRP chemically. Your matrix is now a solid. You can bond TO the FRP mechanically but you can't add to the original matrix.

Some like to add an inlay to their boats. This can and will add strength but it's still a mechanical bond. You're adhering a new layer to the original FRP. The prep to do an inlay is worth some attention. Scuffing and cleaning with acetone so that the surface is as clean as possible will serve you well. Your new layer has to cling to the old FRP. Still worth doing. Especially for you guys that like to push over 70mph. Just take the time to do it well. Patience is your friend.

Some resins have wax in them. Finishing resin I believe has wax. This makes for a harder cured surface but if you need to bond mechanically later you have to make sure the wax is cleaned off.

[T.S.Davis]

2 part urethane is available in different densities. Check out www.uscompsites.com 2lbs per cubic foot is the least dense I believe.

I use this stuff sparsely. Like a bead down each seem at the deck line. Small batches at a time. I would mix less than a 1/2oz and pour it on a piece of cardboard so you understand how much it expands before you try to put it in place. The stuff is crazy to work with. You don't want to trap it's expansion if you follow my meaning. This expands and contracts with temperature unfortunately. If you completely fill a cavity it can mangle your boat. It's happened to me more than once.

Crazy strong stuff though.

[dmitry100]

So should I make some little stands out of thick aluminum rod between the top and bottom area where I will be filling the foam so that it doesn't suck in the hull?
I remember reading that the 2 part foam shrinks over time and pulls the top down with it...

TS Davis: So Gflex is pretty much the same as west systems 105 except with a diff hardener then? What kind of hardener for regular inlays and what kind for mounts?

Currently it goes 97mph and it does have a FG inlay in there. 4oz I believe-- the bondo brand lol. Along with a inlay reinforced hatch along with jb weld to serve as "epoxy blocks" for the hatch bolt system. Since it was already starting to crack in the edges the way it was. It has taken a lot of crashes so far... maybe not as violent as they would be on a bigger part of a lake with more room for acceleration (I normally run it on short span of lake -- like in my videos) and clock speeds using my 10hz garmin glo.
But I think now would be a good time to reinforce the sponson tips area better... I didn't bother doing such a thorough job of it because I thought "not like i'm gonna crash this thing head-on into concrete", yet here we are lol.

[T.S.Davis]

Sounds like the in-lay worked then. That's a bunch O' mph. High speeds are tough at impact.

I've not used the G Flex but my understanding is that it's more of an adhesive. Like for gluing something in place. Might be the same resin though. I honestly don't know. Maybe resin with micro balloons mixed in?

For an inlay I would probably go with the 206 just to give myself more time to get everything in place. You can use 205 but once the stuff kicks your hosed. Then it's like trying to work molasses in a snow storm. It's lost cause at that point. Bad thing is that both will keep moving and even puddle weather you want it to or not until it does kick. To slow that down you could add fumed silica. Also known as cab-o-sil. Weird stuff that is. You can always soak up puddles while you wait for the kick too. It's just added weight otherwise.

I use 205 to place mounts and stuffing tubes. I mix in some milled fiber for strength or some graphite like I mentioned before. Maybe a little silica to keep it from running all over the danged place.

If you ever want to make blocks like you did with the JB weld you can keep mixing cabosil and milled fiber until you get a paste like consistency. Then you can force a shape.

I'm sure others will chime in. I'm not the only one that has played with FRP on here. There are more than 20 ways to skin the cat.

[T.S.Davis]

I remember reading that the 2 part foam shrinks over time and pulls the top down with it...

It does. I wouldn't completely fill the sponson. Just enough that it's picking up 2 surfaces. Like the top and the side. Think bead of caulk where the top meets the side only the bead is foam. Easier typed than done though.

[dmitry100]

So I could use graphite to add strength to the epoxy just like FG milling does to it or is it mostly useful for color ?

[T.S.Davis]

I can't say which is better but I've used graphite that way. Seems to work. Not sure if I could back it with any real science though.

[flraptor07]

I make my own Milled Carbon Fiber, I use my Carbon Fiber scraps and sand them down on my belt sander with a 80grit belt and catch the millings in a pan under the belt. I usually take the table off and put the pan under there. I mix it with Z-Poxy or whatever epoxy I'm wanting to strengthen. Be sure to use a good respirator when you do this!!

[petej]

Not carbon fiber, but, last summer I ran my Motley Crew into a a Kayak
Bow damage.jpg
I flush-cut the damaged bow tip and inserted balsa pieces.
Repairs.jpg
Wrapped with fiber glass, resin, ...
ended up looking like this, MC-Repaired.jpg
Back on the water...