Fiberglass repair the right way?

[davidpm]

I cann't post links so:
Google search "casey fiberglass repair"

I seems pretty clear that Casy says to fix a hole starting with a piece of cloth 1/2" bigger all around than the hole. Then adding layers each layer 1/2" bigger all around for each layer.


Goto Google video and search for "west fiberglass repair"

Am I seeing this wrong. They are saying to start with the biggest piece and make each subsequent layer smaller.


Who is right?
Seems like a really major difference.

[Sailormann]

It Depends.

There is no hard and fast answer. It depends on what part you are fixing, what side you are fixing it from, how it is supported, how much stress it needs to bear, etc. etc.

When you are making a repair, the reason for the increasing size of your patches is to spread the load over as big an area as possible. The smallest piece is going to be the one in the center of the hole, so if you are fixing it from one side only, then this will be the first or the last piece that you put on.

If you are patching the hole on both sides, then you're going to start with the piece that is about an inch bigger than the hole, then lay a larger piece on top, then a larger one, and maybe a fourth one too. When that's set up, you'll fill the hole itself with a couple of pieces and the repeat the layering on the other side.

If you're fixing a hole where one side is butted firmly against something, or you have seald it, then you're going to start with the smaller pieces and get bigger as you work your way out.

[sailingdog]

Davidpm-

Part of the problem is that the order the layers go on in depends a lot on what kind of damage you're repairing and how you are repairing it. There is also some difference in the thought behind which will yield a stronger repair.

If you start with the smallest and work your way to the largest, the idea is that the patches will correspond with the existing laminate the best. The idea of starting with the largest and going to the smallest may have something to do with the fact that fiberglass has the greatest strength if the glass fibers run for a greater distance...and by putting the largest patch on first, when you sand or fair the repair, you'll still have the strength of the longest and largest patch, which might not be the case if you put the patches on smallest to largest, since you'd be sanding through the longest glass fibers.

[Steekel]

It may worth the effort to check out West Systems website. They have alot of information on different types of repairs. You can also purchase literature and DVD instructional material that is very helpful. I have also called their tech service line to get information regarding specific projects, very helpful and patient service techs.

[sailingdog]

One thing, I would recommend MAS epoxy over West...since it doesn't have the same amine blush problems that West Systems epoxy has. The amine blush is also known to be one of the components of epoxy that causes allergic reactions.

[Sailormann]

It may worth the effort to check out West Systems website.

He did that - got conflicting advice - that's why he posted the question. Sit up straight and pay attention !

[Steekel]

Sailingdog, i'm not familiar with the MAS prodcuts. Iv'e used the West products due to easy local availabilty in CA, discounts plus their excellent tech service. Amine blush hasn't been a problem as long as instructions are followed.
Sailernan, I'm not sitting up straight, I'm relaxing in my bunk so maybe not paying as much attention as usual. I would however take West Systesms instruction over Casey's when it comes to dealing with epoxy.

Cheers

[haffiman37]

It does not matter that much whether You start with the big or small patch.
The most important is how the 'new' patch bonds to the old, that the caracteristics of the new patch (flexibility/hardness etc) is as close to the original as possible.
If Your boat is polyester/fiberglass, then use polyester fiberglass for repair and not epoxy/kevlar.

[Sailormann]

Sailernan, I'm not sitting up straight, I'm relaxing in my bunk so maybe not paying as much attention as usual. I would however take West Systesms instruction over Casey's when it comes to dealing with epoxy.

Was just kidding about the 'pay attention' part.

I think it's good to read some things about the way other people do things, but when it comes down to it, it's all pretty simple stuff. You need to know how to mix the goods and how long it needs to set up, but outside of that it's just logic and patience.

[Steekel]

no offnese taken! Key words logic and patience. Especially when it concerns boat repair. practice doesn,t hurt either