sure you can!
but an old longboard or malibu might be easier.
Me an a friend of mine just converted two old longboards one broken in half.
One had too much vee and had to have the bottom re shaped but it was easy and fun.
only spent 60 euros yet.
Not tested them yet.
but I bet they will work

How about converting an old piece of foam into a race board?

same thing, except you have to shape and glass the entire thing.
You need a big old black thought, because of the zero tail rocker.
if the blanck is to thin and has lots of rocker it may be difficult.

in our case we didn't want to spent too much money and effort on something that could turn out unusable.
We just saw the opportunity and understood that half a long board + fins could work, without a big effort (time + money).

In my friends case:
old longboard, = 0 €
two u.s.box fin boxes (one belonged to the board),= 0€
still doesn't have the fins,but he's looking to find some old ones= 0€
resin for the boxes and inserts = 5€
fibre glass scraps = 0€
3 or 4 hours work
total = 0€ + some work

My case
old snapped malibu = 0 €
two new u.s.box fin boxes ,= 14€
cheap plastic 20 cm fins = 20€
resin for the bottom, boxes and inserts = 15€
fibre glass scraps + bottom (4m 6oz)= 28€
2 roasted chickens for lunch at my friends the other day (we're doing this in his place) =6€
10 (?) total hours work
total = 83€ + some work + plenty of fun

Old blank:
add double the resin , fibre, time and chicken ( more money)
but might even be more fun and end up better.

second hand modern race board= can't find it here yet

new north LTD 2010= 800€ (?)
new rrd krace50= 1400...€!!!!

almost finished...

it's just a cheap alternative that might work.
and regarding the ws board, the old surfboards have much similar shapes and are lighter.

...and my friends total is 5€ not 0

Sounds cool. Time for some pics, aye?

....coming up

The lateral force on the fins is huge. Last summer, I kept breaking fiberglass fins one after the other that were meant for surf boards and experimentally used on a race board, until they were made in G10. Do not be surprised if you break your fins.

Norm

Norm, is that why they're canted on the race boards?

thanks kite rider, I'll remember that
if the board works I'll upgrade the fins

I am no expert on the topic, but I'd say no. I am under the impression that the cant on the fins is to allow to ride the board with an angle relative to the water, like as with a twin-tip board, hence the toe-side fins are not as much in the water, therefore generating less resistance to forward movement. The amount of cant is personal preference and imposed by intended design of either the fin boxes or the fins themselves.

Personally, I prefer less than more, so I can ride the board flatter. For instance, my main race board has US-type fin boxes with virtually no cant. It tracks super-well close hauled and beam reach but is not as stable when sailing broad reach. I think boards with more fin angle track less close hauled well but are more stable on broad reach. A race board designer once told me that I cannot have it all, it is a question of compromise. Read Stance on race board for my impression of different boards with different cants.

Norm