: My university has a large engineering department so I'm taking advantage of
: the composites laboratory in the next couple of weeks. This is my idea for
: a paddle: Form a carbon fiber sleeve into a shaft (how small a diameter
: can I go and still have enough strength?)

Why small?

You'll get good strenght from the CF, and good impact and puncture resistance from your glass and wood. Why not, "How big can I make the shaft for stiffness and strength, and still fit my hands?" Then, "How thin can I make it and still have light weight".

:then cover the shaft with a
: thin layer of wood in some way to give it some warmth.

Nothing like the aesthetic warmth of wood. Go as thin as possible to save weight. The thinner you get, the easier it will be to wrap around your mandrel.

With veneers, you'll probably acheive complete epoxy saturation--thicker wood=heavier with epoxy.

: Then possibly cover
: the whole shaft and blade in glass. I found a place that sells ash veneer.
: Could I wrap ash veneer around this carbon shaft and get it to stay
: somehow? I haven't worked with ash before so I don't know how far it can
: be pushed.

Why use ash? You're not getting as much strength from it as your CF and FG. Birds Eye Maple would look amazing...burl mahogany....crotch walnut...birch burl...

Sounds like a cool experiment. I thought about the same thing to build a bike frame...might do it someday, too!

Shawn