Poly or Epoxy?

I searched and searched, but did not find the answer I was looking for.
I know this topic has probably been beaten to death, but here goes anyways.

I am preparing to fix my hull delam tomorrow and cannot afford the Git Rot that's recommended. Is there any reason why just plain old "No Wax" Poly resin won't do the job?

JOhn ><>

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1974 Hobie 16 (not to mention my age, but that's the year I graduated from High school)
1993 Hobie 17 For Sale
JMBoatStuff

Polyester resin does not have the adhesion and the strength to perform a delam repair. It will simply delaminate again.

If you don't have the money for Git-Rot, save up until you do. Don't do the repair half-assed. It isn't that much more expensive.

I tried both before, after they dry they just fall off.

Poly will stick to poly

Epoxy will stick to epoxy

Epoxy will stick to poly

Poly will not stick to epoxy

When in doubt, use epoxy for all repairs

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Bzzzz. Wrong answer.

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Sail Revolution
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Was the surface properly prepped?

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Marc...
1978 Hobie 16 Keoke, sail# 36 84

I bow to your vast knowledge Jeremy. Could you expand on why?

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I was kind of being a jerk, just because I've gone "there" before.

I'm going to keep it simple this time:
Epoxy for adhesion (Gluing the outer skin to the foam and inner skin).
Polyester for laminating and coating (Gelcoat).

Reason 1: Polyester has a difficult time curing over epoxy, and will often not cure. At the bare minimum, if it does cure, it will often flake off or blister over time.

Reason 2: Epoxy is almost double the price and the superior adhesion is not needed for lamination, since the entire boat is polyester anyway.

Reason 3: When the boat comes to a fiberglass repair guy, and he fails to realize that someone in the past tried to "fix" the boat with epoxy (marine tex), and his gelcoat fails, he's going to be angry and charge you triple.

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I agree with all of the above (except for the jerk part). The reason I said to use epoxy for repairs is because of #3.

In my case I did multiple repairs on the inner tub of a Sabot using polyester. It would last about six months before lifting off the deck. This year I went with epoxy. It's still solid after nine months

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Proper prep and repair engineering is needed no matter what material you use.

A repair done correctly will not fail unless there is more damage to the area, or the part is not designed properly to begin with.

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Crap, Crap, Crap, That's what I say! This repair stuff is not intuitive.

Here is my deal. I am repairing a 1986 redline 18 that has more cracks than the Santa Cruz sidewalks and I plan on racing her if I can keep her afloat. I have used all epoxy to this point and I am planning on touching it all up with gelcoat. What do I need to do to make the poly gelcoat adhere the epoxy.

I wouldn't screw with this boat if it wasn't 35lbs lighter than my 83.

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H18 '85
H18 '89 "Knotty Passion"
H20 '96 "20/20 Vision"
Fleet 259 Central Coast California

Here's the general rule for all boats. Use what the vessel was built out of for repairs, unless you're bonding something.

Do a test section before you gel the whole repair. Sand with 80g, and wash the epoxy thoroughly with water, then a quick swipe with Acetone. You may get lucky, but gel really doesn't like to cure over epoxy.

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Is there a better brand of Gelcoat to do what I am doing? I purchased a small lot of Tap Plastics brand and I plan on testing first. Also, What size tip do you use on your guns to spray the gelcoat?

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H18 '85
H18 '89 "Knotty Passion"
H20 '96 "20/20 Vision"
Fleet 259 Central Coast California

Ah Epoxy rears it's ugly head again. I've used epoxy for several repairs over the years with excellent results (NONE - ZIP - NADA - have ever failed). The main exception is for delaminations, where I use polyester due it it's better flow into small places via a long 14G syringe needles.

So you come from the other school, using poly for delamination repair. So now I sit here with 2 gallons of poly resin and a gallon of epoxy with super slow cure "tropical" hardener.

I am fixing delamination on the tops only for my Hobie 16, which product do you recommend for that?

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1974 Hobie 16 (not to mention my age, but that's the year I graduated from High school)
1993 Hobie 17 For Sale
JMBoatStuff