West Systems epoxy products are great.
I faired my keel with West Systems epoxy and a generic low density filling compound this winter. Worked great!
I found that you will need to use about a 1:1.5 /1:1.75 ratio of mixed epoxy and filler. It should have the consistency of pastry dough. If not, you will find it will sag before it kicks off. This will cause you to do a lot of sanding...don't ask how I know this.
At $80 odd dollars a litre it's expensive but it is worth it. Don't buy their filling compound, it's really expensive. You should be able to find a generic one at a 1/4 of their cost.
West Marine sells an epoxy mixing and application kit that is worth the extra dough. You get latex gloves, mixing bowls, mixing sticks and an applicator for about $20 bucks.
Good luck. http://www.google.ca/url?sa=t&rct=j...WmtYFg&usg=AFQjCNGTBR1xTWqJpkXfRvaee7B9zardGQ