Nothing like counting on the Internet is gonna work. Like, I for one never use it

Let's try to systematize, a Bob Hawke would say.
There are 3 kinda crowds:
a) those that renew and sail fairly recent gear
b) recent gear, but only from used market
c) old-timers that circle around on Narrabeen lake (no offense) on old gear
d) those who own boards but haven't sailed in 125 years
The latter are not really active, perhaps they took up kiting already for that reason, whatever. Let's ignore them.
To "calculate" a), we require only 2 approximations:
a1: total number of new boards sold each year in Australia.
- get or approximate
- 1000 sounded a lot, but whatever.
a2: assume for that crowd an average number of renewals per year.
- some buy new every year
- others buy one new board every 3 or so
- for argument's sake here, say 1.2 on the average.
The crowd at b) is small, as sooner or later they join the Tupperware party.
Let's say they're .25 of a), for argument's sake.
To approximate c), just say for each 'renewer' with recent gear, there is say .7 that sails occasionally at MacQuarie and Canberra and Pitt and such with an old Ten Cate or Windsurfer.
Plug in the numbers and ratios you want. For my tentative numbers above:
a = (a1 * a2) = 1200 sailors that buy recent new stuff
b = (.25 * a) = 300 sailors that buy used only
c = (a+b) * .7 = 1000+ cottage sailors (no offense again)
= a paltry total of 2500 active windsurfers in Oz.
The equation works IMO, it's a matter of plugging in the numbers as you see them.
However, they'll never add up to very much.
P.