I have an iS 111 and don't make many successful tacks. Three things that may help.
1. When heading up, you have to tack while the board is still on plane.
2. You have to move from one side to the other very quickly with no pause around the nose.
3. Keep the mast racked back toward the tail, don't pull it up to vertical. This will allow you to keep your weight a little further from the nose.
Then practice, practice, practice (in the summer). This is my weak point, I don't practice often enough.
Anyone else with other helpful hints would be appreciated.
Formula 160; iSonic 111; HiFly Move 105; Tiga 263; '85 Mistral Superlight.
Maui Sails TR 11.0; 9.2; 8.4; 7.6; 6.6; Maui Sails Switch 6.0; 5.2; Maui Sails Global 4.5; 4.0.