RE: Board and Sail
As a novice windsurfer in Perth Ive found the local w/s retailers in Nedlands and North Fremantle to be more than just helpful. The Nedlands store hires and supplies Starboard&Severne and the other sells Hot Sails&Goya both with no sales pressure.
From late spring thru summer the sea breeze can get up to 30+ knots,great fun but suicidal on a wide board.A Carve 122 seems appropriate and ive seen quite a few in use on the river.
If Starboard is your thing go to Nedlands.
Weed fins are not reqd on the river ,sail sizes seem to range from 4.5 upwards,myself(93kg) with 4.7 5.3 5.9 6.5&8.5. As you can see from the sail sizes its not always blowing here.
If youre still concerned about board size hire the Carve 133 from Windforce and if you manage o.k. buy a 122 .