I have been doing alot of reading about repairing and glassing cracks. I have a crack in my hull and was wanting the strongest possible repair, and it seems that fiberglass mat will provide the best strength? I was looking into west systems epoxy but it is really pricey, i can get a gallon of good 3m brand automotive epoxy resin for about $50 a gallon with hardener? Is there really any difference? I dont want to have to do this again because i was being a cheap azz, but i dont want to spend extra money if its not needed.
Thanks

The mat is by far going to give you the best bang for the buck. the bilateral is for beefing up corners and complex contours but very difficult to work with (like trying to wet out a rolled up beach towel).

Try TAP plastics, they sell a marine grade epoxy that is priced prety competitively   http://www.tapplastics.com/shop/product.php?pid=27&   

Not trying to talk you out of or into anything, but I use epoxy because of the flexibility and quality of the finished product. One thing you have to remember, a gallon of polyester makes a gallon of product, a gallon of epoxy, once the hardener is added, is about a gallon and a quarter, the math still makes the epoxy expensive, but you will throw less epoxy away due to the controllable kick time (potlife)...

GT

Thanks, looks like i will probably be ordering from them. Should i use a filler to strengthen the area where i am doing the repair or is that not needed?

Fillers are weak, the strength is in the mat, not the resin or the gelcoat....

Fillers are only for filling depresions and small imperfections...Pick up some Cab-O-Sil whick is powdered fiberglass, you can make your own filler that is about ten times stronger than say Bondo...

GT