it takes no skill to use a speed3 (unlike the speed2 or older FS kites), i lend it to a beginner, he managed to waterstart when he couldn t with the other kites (low wind day). he relaunched the kite as well without any troubles (LE towards the water and the other time kite was in taco mode), hell even my GF who doesn t kiteboard at all , can fly it on static mode.....and relaunch it
-the advantages for a beginner: very good air stability ( less than peter lynn kites but way better than LEIs), good depower, good raw power for waterstart.those kites are slow so even on a bar error u can correct the wrong action before getting punished (unlike a 10/ or 7 kite), easy and fast to repair, can still fly punctured or teared ( but don t crash it in the water, depending where the tear is), solo lauches.
-inconvenients: relaunches to be teached and trained a bit on ground (to be sure they understood the relaunch method) or shallow water (pulling one rear line or 2 rear lines for reverse launches). long time air drop out ( 20/30mn) the kite will deflate slowly ( but should reamin in the air at 5/6 knots). bridles , if u are on a lake shore ( tree branches) or seaweed.
i lend it to the beginner (80kg around, much heavier than me), the wind was at 10 knots, he couldn t go with a 14 cabrinha crossbow (couldn t stay on the board and finished in tea bag mode), the Speed3 15 allowed him to waterstart and go upwind ( he never managed to go upwind before, cross ride at best), he said it was a good thing that the kite was easy to park because it was slower to sin/turn than the Xbow , i told him to buy a bigger board so he could go with the X-bow.if the kite don t give enough power, get a wider board for board speed.
if the wind is laminar ( coastal wind), i think u can teach with a 15/19/21 ( weight dependant) to a beginner (8/10 wind knots), the depower is enough for them, if the wind picks up 4/5 knots ( after that, i think a regular rider should keep the kite or the beginners go for smaller sizes), a 21 in 8knots , it s pretty much the same as teaching a 12m² in 12/13knots. the raw power would be the same.
for cheaper prices, u can go for a regular speed3 , not the deluxe one, pretty much the same prices as the LEI big kites. deluxe have less inertia ( lighter fabric) and stay better in lulls ( lighter fabric) and u save up around 300€ with the regular fabric.
as a teacher, u might ask flysurfer to demo a kite to test it?