George,
If you use the 3.25 oz. tightweave glass, try some sample layups first. There is a slight learning curve. I only needed ONE fill coat before sanding, on the outside, no fill on inside, except the cockpit area. This really reduces the epoxy needed.
You may want to use two layers of this glass which should still be lighter than using plain weave. I tried using one layer on my latest boat, but this 20 footer is built with 5/32" hull strips and 1/8" deck strips. My single layer 3.25 oz. layup also included a lot of unidirectional Carbon Fiber reinforcement on a 20' X 20" kayak that only weighed 23# before installing a racing rudder and carbon fiber foot board/rudder control.I had only used 3/4 gal. of epoxy to this point.

It seemed I was well on my way to achvieing a sub 30# rocket. However, when I lifted one end of the boat, I detected a slight flexing (bending) of the hull. If this boat was only going to be paddled on flat water or with a light weight paddler, it would not have been an issue. However, I decided to add a second layer to hull and deck outside. This second layer did the trick. Everything is now stronger and much stiffer, including the 1/8" deck.

One possible light weight layup: 2 layers on the hull outside, one on the inside with extra layers inside cockpit area, one layer on deck with extra fore and aft of coaming on the inside. This assumes 3/16-1/4" strips. This layup should yield a very light boat. For a stronger and still light boat, 2 layers of 3.25 oz everywhere. BTW/ Raka also sells this glass.

If you go with Raka epoxy, buy the 3 gal kit. It is the best $ value. 127 Resin, 350 non blush hardner. As Bill mentioned, you should factor shipping into your epoxy cost. A more expensive local epoxy may not actually cost more in the long run. Also get yourself a cheap digital scale from Harbor Freight and weigh your epoxy, mixing ratio 100 to 44 by weight for Raka 127/350. You will be able to mix the smallest amount needed without waste.
Some notes about Raka: The 350 hardener is trully non blushing. I have never seen air bubbles anywhere in my layups and I apply with a roller. Raka used to be the slowest curing epoxy you could get. I have found lately it cures much, much faster which I like. I can now wetout and fill in the same day. It's not as fast as Wests, but it's about perfect for my liking.

Larry

: Hi Larry,

: Thanks for the feedback. Second boat, first stripper - and I'm aiming for
: lightweight - top of the car is getting higher every year! I baby the
: boats in terms of avoiding grounding them on launch/landing, but enjoy a
: bit of rough water (but then it's only inland lakes). While I will be
: paddling this some, it's actually for my 120 # daughter, too - I suspect
: the lighter layup will suffice. And so far, the RAKA prices look the best
: of the sites I've found.
: And I notice it rated well with Vaclav's site.