I bought a 3 gal. Raka pkg. for my first boat, nearly 17'. In the end I had nearly a half gal. of resin left and 1/4 gal. of hardener. The 6 oz. cloth was completely filled and the boat came in a bit overweight.
That said, a 3 gal. pkg. is probably more economical than buying quart packs and trying to hit it exactly.
You're going to build another boat (yes you are) and at least a paddle or two so leftovers will be used. Plus you'll start finding other uses for the stuff around the house.
I just used 4 oz. cloth on a solo canoe and probably could have used it on the kayak, also gently used. It sure is easier to work with.

Ian

: I'm thinking I'm going to order some epoxy and glass here soon. I'm
: really leaning towards the Ecopoxy stuff I've read about here.

: How much should I buy? What's the average amount used on a 17'
: boat? I was thinking 3 gallons.. 2 gal. resin, one gal.
: hardener. My thought is a fill coat first then using 4oz glass.
: Does 3 gallons sound reasonable?

: Side note, the boat will be lightly used.. is 4oz glass enough?
: I'd imagine mostly used along the shorelines of Munising/Marquette
: Michigan as Glen's previous post shows :) My mom has offered up
: her spot on the Lake across from Grand Island as a first
: launching point.. She'll even supply the campaign!