Gel Stress Fractures

[aod]

Over the year I have picked up some tops tips from this site so I thought that as I have to deal with a number of gelcoat stress fractures I would see if there are any top tips out there

My current plan is to follow the fractures with the edge of a screwdriver and then fill and fair!

Any other suggestions would be very welcome.

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[oldsaltoz]

G'day aod,

I would be looking at the cause, it will avoid further repairs later, the most common cause is bulk heads and bunk tops, they can be made a little stiffer by adding 2 or 3 lays of glass, start with a strip about 6 inches wide, then another 2 inches less and so on.

Not a lot (Any) info in your profile so it's a bit difficult to be more specific.



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[Avocet]

I agree, if they're due to a working load (like a shroud plate) the laminate will need reinforcing behind with a few layers of resin and mat. You really need to grind back the inside surface to get a good key - new GRP never seems to stick that well to old GRP.

If they're as a result of a berthing "miscalculation" you should be OK just grinding out the gelcoat back to laminate and filling it with gelcoat filler - although if it was a hard knock, I'd still be inclined to reinforce the inside anyway. BEWARE, it's incredibly dificult to get a perfect colour match on faded gelcoat - and even if you do, in a few years the new stuff will have faded more than the old stuff! Make sure you buff the old hull as much as you can beforehand and try to match the colour of the buffed part rather than the faded part.

If it's painted, ignore all the above!

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[oldsaltoz]

Re: << new GRP never seems to stick that well to old GRP>>

Standard wax /poly resin will not stick too well to old (More than 8 weeks) fibreglass.

However epoxy resin will provide a secondary bond and can be 40% stronger, the trick is to go for a ratio of one part resin to one part cloth when using epoxy, too much resin will weaken it.

Standard wax/poly resins like a ratio of 3 parts resin to one part cloth.

I hope this helps.



<hr width=100% size=1> Old Salt Oz /forums/images/icons/cool.gif Growing old is unavoidable. However, growing up is still optional.

 

[Avocet]

I've been told that although epoxy does stick very well to polyester, polyester won't stick to epoxy if ever you have to do any further work.

...don't know if it's true though...

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[maxxi]

Another consideration, epoxy will not work with chopped strand mat as it is incompatible with the binding mediums. Therefore, if using epoxy use woven rovings only.

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