Poly or Epoxy?

Here's the new glass and gelcoat sole. Notice the stipple rolled gelcoat nonskid? Came out good!





The deck was looking a little ratty, So I stipple rolled some gel after careful prep.
This is the first coat, before we taped in the soft turns.




Now that's a proper hijack! My point is, you can use whatever you want to fix your boat, it's YOUR boat afterall. It's not mine, and it's not fastcat's. YOU, ultimately are the one that will either be happy with the repair, or think it's junk. Or you might get so frustrated that you throw your hands up in despair. Remember, sailing is supposed to be fun!

Cheers!

And fastcat, my repairs don't fail. People's lives depend on some of the things that I glue back together. Oftentimes, it's my life, or my son's, or wife's lives. Thanks for the personal attack though! Cheers, mate!

Hijack off.

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Hi Jack is almost over. Struck a nerve I see. Jeremy you put out a good product and take pride in your work, AS DO I. However, your arguments for what is the "right way - only way - your way" sadly doesn't pass muster. I take exception to most absolutes, because there aren't many. So I shall agree to disagree, absolutely.

Can you clarify this a little bit for for me? Where the new repair meets the old material is a secondary (non-chemical) bond, right? And epoxy is better for secondary bonds (hence the use for bedding hardware), right? So wouldn't you have a theoretically stronger attachment if the repair patch if you used epoxy instead of poly? Or, if properly done (beveled etc), is the secondary bond between new and old so overbuilt that it doesn't matter?

Also, what are your thoughts on the method West Epoxy suggests for removing Amine blush and prepping the surface for Gelcoat? Ever tried it, does it work?
http://www.westsystem.com/ss/assets/HowTo-Publications/Fiberglass-Boat-Repair-and-Maintenance.pdf (starting on page 7)

Not trying to stir anything up with this, I just don't have much experience with repair of polyester structures and am curious!

Thanks,
Steve

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1990 Hobie 18SX #2077

Great questions.

If the repair in engineered properly, either product will work fine. If done right, new glass will not just fall off of a repair. The problem is that amine blush removal is spotty; sometimes you have good luck, and sometimes not.

If you use epoxy for the repair with the intention of gelcoating later, you're basically asking for the gel to mechanically bond to the epoxy, which it doesn't like to do. The failure rate is high.

I've seen enough failures of GC over epoxy, done by very competent fiberglass repair guys, to not suggest it to novices. It's simply not worth the trouble, and added expense. The benefits do not outweigh the potential problems. Generally, the added bonding of epoxy is not necessary, and where it is, I use Vinylester resin, which is compatible with GC.

Here's an example of where I used epoxy last week. The angle of the top of this rudder was wrong, so I cut the top off, leaving an area attached near the post, beveled the edges, then glued and lammed it all back together. I decided to use epoxy because it's an underwater fixture, I was bonding the top back to the foam core, and the coating is an epoxy barrier coat.

If the coating was gel, I would've opted for vinylester.



Since I used epoxy, the repair took 3 days instead of 1 if I were to use vinyl or poly. That's another huge drawback to epoxy. The cure time isn't easily adjusted, which almost hosed me in this instance, the next day it rained.

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Jeremy:

Its good to see Terraphobia almost back in action....looks good Jeremy
(I bet Craig is almost as happy as you )

I have a good picture of you in San Diego shooting a picture of us Hobie 20 sailors on the broadway pier.... that I will have to send

- Dwight

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Dwight Manning
Hobie 20 #916 San Jose CA 2000 Alter Cup
Hobie 20 #16 San Jose CA (Jordan) 2000 Alter Cup
Hobie 18 #916 Santa Cruz CA 1989 Worlds Boat
Hobie 16 #16 San Jose CA (Jordan) 2005 Custom Main
Hobie 16 #54466 Calling Lake Alta Tequila sunrise

Nice, Dwight! It was sure great to see a whole crew of familiar Hobie faces on the pier when I was on the 45 course!

Cheers!

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GOOD STUFquestion time for Jeremy.
I have read on several dif. forums about hull repair and it seems you just mayhave done one or two, the question is the teqnique where you fashon a patch on wax paper and thread it through the hull hole or break then hold in place w monofiliment to (relam) over it . finish and gel.
would you use it on the dammage here? I have 2 H16 with the same trailer bite!
and I did buy them this way....one was covered with bondo the other with tape and paint.[img]http://i1203.photobucket.com/albums/bb394/rwl1967/SANY3446.jpg[img][/img]http://i1203.photobucket.com/albums/bb394/rwl1967/SANY3449.jpg[/img]
thanks rich

Oh Crap! Ill try again!

and one more thanks for not laughing

For your repair you need to grind that skin a little more, get rid of the rotten foam, and check the inner skin for damage. This is the part of a repair that will help you determine how to properly engineer the repair.

You want the inner skin to be solid and glued to the foam, and the foam to be solidly glued to an outer skin. You're going to be laminating the outer skin on the outside of the hull, but you need to taper the edges. Like this:



A taper ratio of 20 to 1 works well for Hobie hull repair. Up to 50 to 1 for areas that will encounter more stress. Standard is 12:1.

I like Rick's well-documented trick with the mono-filament, but I always have a difficult time getting good, solid adhesion. I'll describe how I do it below. (Someone can post the Hotline article.) This method is generally only used on a spot where the glass is solid...with no foam underneath. Where there IS foam, you need to glue the skins back together to regain the proper structure. Any part of the hull structure that isn't bonded together, is damage, and should be ground away.

1) Grind out the outer skin and rotten foam, leaving the inner skin to use as a flange.

2) Laminate the new piece of glass on wax paper, or a flexible piece of plastic like a bondo board. Don't use PVA, as you want it to stick to something eventually.

3) Now, since you're ADHERING the new piece to the inner skin you want to use vinylester mixed with a good thickener to make a putty. You could also use Epoxy, but be careful not to get any on the exposed area. You don't need to glue it to the inside of the hull if you're in a spot where there's foam, glue it on the outside of the inner skin.

4) Fair it. Re- foam the core. Laminate the outer skin, hotcoat with gel and you're done.


You can do this!

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Happy Hobie Holidays Jeremy. I hope that you have a great X Mas with your family this year!!!

Thanks for all of your continued support - you are a true asset to Hobie Cat Co.

Ok, I understand to remove the bruise...delam and to feather and expose plenty of old glass to adhere to.
I understand the patch building.
re-foam..you lost me there.
and re-laminate on the outer side I understand.

with no foam do I putty gell adhere the patch directly to the GOOD inner
ply then build with glass mat and resin
or do I make a hollow sandwich and finish like the old tub buggy?
If I am to fit foam where is a sourse via the net.
thank you Rich

Man, I wish I had pics...

First, your boat is a foam core sandwich. Skin-foam-glass. Capiche?

I am assuming that there is damage to the inner skin with a punch like that. Maybe, maybe not, you have to investigate. You want to grind the outer skin away until you get to where the foam is bonded to the core. Your foam looks really bad anyway, so not much loss there.

Use a Dremel Tool or something similar to grind the foam away in order to inspect the inner laminate. Don't nick the inner skin. You're just inspecting it still at this point. If the inner skin isn't damaged, use some Divinicell Foam or just mix a slurry of resin and microbaloons, and replace the core. That's what I mean by re-foam. The core gives the hull structure. The distance between the skins is the strength.

http://www.jamestowndistributors.com/userportal/product.do?part=42743&BASE

Does that answer your question?

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YES!!!!
Now I understand completely!
I do understand the foam sanswhich concept
and now I can do as yo have explained, thank -you
I had no clue at all on the re-foam ..much better
I will post a few shots of this in process for future use. (provided it looks good!)
and this 74 is just for practice. my 80 has the twin or brother bite on it.
but no soft spots and no paint just gell coat and bondo!
I cant thank ALL the people who post enough!
May you all enjoy you holiday however you may choose!

Here's my personal email if you run into trouble.

[email protected]


Now, get to grindin'!

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