Gel Coat, why?

[BigCat]

Vinylester is impermeable enough that it is used in blister prevention and repair. You can get vinylester gel coats. It is stronger than polyester gelcoat, as well as being the solution to water penetration issues. Iso/NPG is the next step down in quality from vinylester gel coat.

See: http://www.zahnisers.com/repair/blister/blister1.htm

http://www.jby.com/OSMO_web.pdf says, "Again, over the years we have done extensive independent testing of coating systems using epoxies as
well as vinylester resins. The vinylester resins outperformed the epoxies in accelerated moisture testing and is the reason we
are able to achieve such a high success rate." Since you can get a 10 year warranty from them, I'd say they have put their money where their mouth is.

[w42]

Generally, a good gelcoat, especially v/e will outperform LPU for color and lustre, if maintained with the occasional buffing/waxing.

There are new arcylic paint systems that will outperform LPU in look and age.

[dkall]

One more reason, Gelcoat life approx 20 years, LPU life 10 - 12.

[cat man do]

The weight of gelcoat is huge

On a Performance Multi at least, weight saving is everything

Dave

[Roy M]

Uh, guys.... The LPU figure is for a single application with 10-15 years of no significant maintenance. The gelcoat figure, of whatever duration, is for regular cleaning and waxing every six months. A wax job for a forty foot boat is a good day's work (more for a multihull). You do the math.

[seawind_hazzie]

I have a timber deck one inch thick /25mm it has a fibre glass matting over the timber wrapping over the gunwhales onto the hull,, and has been painted over with about 10coats of poor quality paint which is now cracking and looks ugly,, I want to remove the paint exposing the glass matting and from this i want to know can i cover it with gelcoat ,i would rather not paint again, any advise would be appreciated... cheers harry Bryce... SV Seawind.. Qld. Aust.

[delmarrey]

My boat was all hand laid-up and has no gel coat. I do have to give it a fresh coat of paint about every three years but it is durable and looks just as good as any gelcoat (every 3 years). And if there are any changes or repairs, they are simple.

[Stillraining]

Ya but Del...your a daw-gone magician that aint a fair analogy...I vote you off the Island...

[Christian Van H]

A couple more things about Gel Coat; all fiberglass boats "work"...they constantly twist,flex and expand/contract. On alot of early boats gel coat was applied with the "more can only be better" philosophy. Problem is, Gel coat and glass expand and contract at different rates, and Gel coat is not too awlful flexible. Result... stress cracks everywhere. Now, below the waterline, I vote for epoxy. Make sure the epoxy you apply will stay slightly flexible though (MAS epoxy is my personal fav), and if you've removed the gel coat for any reason (Spidering, damage, etc.) see that your epoxy gets good penetration into the substrate. How many coats of epoxy for a barrier? Depends on the build but IMHO, 6 minimum.

[delmarrey]

Originally Posted by Christian Van H

I vote for epoxy. Make sure the epoxy you apply will stay slightly flexible though (MAS epoxy is my personal fav), and if you've removed the gel coat for any reason (Spidering, damage, etc.) see that your epoxy gets good penetration into the substrate. How many coats of epoxy for a barrier? Depends on the build but IMHO, 6 minimum.

There are different grades of epoxy, some hard some soft. I buy mine at Fiberlay. They have a 2:1 mix and a 4:1 mix the 2:1 is a softer more flexible cure. I use the 2:1 on most of my projects due to it's ability to hold up to the stress.

But, if I need a filler I use the West Systems. It makes a better filler IMO and it sands better (doesn't load up the grit as fast).

[Christian Van H]

Originally Posted by delmarrey

But, if I need a filler I use the West Systems. It makes a better filler IMO and it sands better (doesn't load up the grit as fast).

Yup, I agree. I think its because the West gets so damn hard. When I'm done with a batch and I crack out the mixing cup, the West is as brittle as glass. Whatever you're using, keep it up! I can tell from your pics that you know what you're doing!

[delmarrey]

Originally Posted by Christian Van H

Yup, When I'm done with a batch and I crack out the mixing cup, the West is as brittle as glass.

Since you mentioned it. I found the same with the West's. I can usually use the same mixing cup over. But with the 2:1 I can't even get the residual stuff out! I have to rinse it clean with MEK or throw it away.

[Christian Van H]

Brittle as glass and flex dont mix!

[Hudson Force]

No special care has been given to this 1973 hull of this Morgan that has logged over 40.000 miles. No cracks, no fractures, no crazing, no blisters on a fairly inexpensive production boat and it's not unique. It seems to me that the gel coats can perform well.
Picture012.jpg - Image - Photobucket - Video and Image Hosting

'take care and joy, Aythya crew

[delmarrey]

Originally Posted by CaptForce

No special care has been given to this 1973 hull of this Morgan that has logged over 40.000 miles. No cracks, no fractures, no crazing, no blisters on a fairly inexpensive production boat and it's not unique. It seems to me that the gel coats can perform well.

'take care and joy, Aythya crew

Very good!

The older boats were over built just a bit, which made them less flexible. It's the newer boats one has to be concerned about. Cost vs. Profit!

The first glass boats had thicker hulls and usually solid glass. Now with years of experience they are commonly cored with as little glass as they can get away with, pushing the envelope (To increase the operating capabilities of a technological system).

That's one reason I chose an older boat, although cored, to rebuild rather then buy new. It costs the same to get the same, or better.

BTW- It's usually the smaller boats under 30' that acquire the stress cracking, most commonly around the cockpit and hull joints.