When I take off in my boat I have to trim my motor at 3. When I get my speed built up I can trim to 4 which the boat handles alot better and drives alot bettter. If I take off with my trim set at 4 I get alot of ventilation. Is this normal? If I drive my boat around at 3.5 or lower it steers hard to one side. Where at 4 it steers straight. I have a 17 foot flatbottom boat with a 90 hp yamaha motor. Any help or ideas are appreciated.