OH BOY! Here we go again

[Gary]

Ok my PT Supersport 45 has performing fantastic but is slowly loseing speed. Was always around 82-85 mph on 18 vlots but has slowly dropped in speed. 82,81,80,78,and now 77mph. Rpm on data logger is 2,000-3,000 less that its fastest speed.The funny thing is it still goes a repeatable 65mph many many times on the same runs with 14 volts like it always did. Batteries are all new so dont think it is that. Boat still screams and seems like its running like always but data logger tells a diferent storey. All temps are the same, batteries preheated to same temp and strut in same place. Any thoughts? Again boat still runs fantastic other than that.

[slyman]

Ok my PT Supersport 45 has performing fantastic but is slowly loseing speed. Was always around 82-85 mph on 18 vlots but has slowly dropped in speed. 82,81,80,78,and now 77mph. Rpm on data logger is 2,000-3,000 less that its fastest speed.The funny thing is it still goes a repeatable 65mph many many times on the same runs with 14 volts like it always did. Batteries are all new so dont think it is that. Boat still screams and seems like its running like always but data logger tells a diferent storey. All temps are the same, batteries preheated to same temp and strut in same place. Any thoughts? Again boat still runs fantastic other than that.

How are the bearings on the motor? Maybe they are begining to wear and it only shows up at high RPM's.

[Rumdog]

My guess is cumulative damage from a SAW type setup.

[JimClark]

What kind of Batteries?

[Gerwin Brommer]

Demagnetising of the motor.

[ED66677]

agree with Gerwin!

[Gary]

Thunder power 45-90 4,500mah 18 volt in paralell. Bearings seem fine and it still has good "magnetism" that i can tell. Mabe i will swap out the hydra wed. and see what happens. Seems strange though.