Sydwayz, gave very good detailed explaination of tab use but if you could afford it take the Tres Martin school. Also if you can find a current DVD copy of the owners video that comes with Fountain boats you you watch that. They give out some good tips in boat handling.
I had a 2000 Fountain 29 Fever and I found out and received a tip from Reggie jr and Wyatt Fountain that in rough water try the tabs at 4-4.5 (3 was nuetral on my boat) and trim the drive out to 5-5.5. This was a great setting for full throttle in rough 4 footers and heavy slop. However this setting did not work well at anything slower than full throttle.

So basically there is not perfect setting as it all depends on the speed of your boat and the weight/balance of the boat at the time.