PLdrive
05-14-2001, 10:20 PM
I have a few questions and a few observations for you guys running in the upper 90s and above on a 2003 hull. I have a grand sport with a 280 long shaft (stock sport master). Motor is just broken in and I am still getting used to the 280(previous motor 225 pro max).
Conditions
Winds 2 to 3mph, water smooth
Back Ground
Prop shaft is a 1/4 inch of above the pad. Prop is a 28 chopper II (stock) set back 10 or 11 inches (can’t remember, I am on the road this week)
First 3 runs right at 100mph (7400 to 7500RPM) no GPS
Sent prop to Tim Hackney (Allison cut)
Second 3 runs??? (Not sure needle is past 100mph, I’m guessing 102 103 (7300RPM) I KNOW rmps dropped. Tim is going to make some adjustments to bring RPMs up.) Prop is quicker and faster then stock chopper II on my boat. Comes out of the water mush quicker.
Now here is what I am seeing. O to 95 boat runs straight, fairly easy to drive. But as it get s closer to 100 things start to change (both props); Boat does not want to stay on pad (falls to left and to right, very difficult to balance), I have made very small adjustments in weight (side to side) to no avail. I am beginning to think the gear case is developing enough lift to raise the rear of the boat enough to cause the adverse handling. I am planning to raise the motor up to see if handling improves.
Have any of you experienced this? I will post at a few other places as well.
Thanks guys for the help!
Mark
Conditions
Winds 2 to 3mph, water smooth
Back Ground
Prop shaft is a 1/4 inch of above the pad. Prop is a 28 chopper II (stock) set back 10 or 11 inches (can’t remember, I am on the road this week)
First 3 runs right at 100mph (7400 to 7500RPM) no GPS
Sent prop to Tim Hackney (Allison cut)
Second 3 runs??? (Not sure needle is past 100mph, I’m guessing 102 103 (7300RPM) I KNOW rmps dropped. Tim is going to make some adjustments to bring RPMs up.) Prop is quicker and faster then stock chopper II on my boat. Comes out of the water mush quicker.
Now here is what I am seeing. O to 95 boat runs straight, fairly easy to drive. But as it get s closer to 100 things start to change (both props); Boat does not want to stay on pad (falls to left and to right, very difficult to balance), I have made very small adjustments in weight (side to side) to no avail. I am beginning to think the gear case is developing enough lift to raise the rear of the boat enough to cause the adverse handling. I am planning to raise the motor up to see if handling improves.
Have any of you experienced this? I will post at a few other places as well.
Thanks guys for the help!
Mark