four blade or top water prop?

[masterofnone]

I have a 1990 tracker 17 foot deep v that I repowered with a '78 merc thunderbolt 500 50 hp outboard. Engine runs fine but when boat gets on plane the motor rpms go up and the boat slows down. This also happens at a slower rpm when I turn in either direction. After researching and measuring it appears that I put a short shaft motor on a transom that needs a longer shaft. The AV plate is almost 3 inches from the bottom of the hull when motor is at its lowest setting. Current prop is an aluminum mercury 10 7/8 x 11 aluminum, not sure of wot rpm but gps speed maxed out at 15 mph before ventilating.

Question is, can I put a 4 blade prop or a top water prop on to make this motor work?

 

[SparkieBoat]

Re: four blade or top water prop?

you can try but my guess is that you need a long shaft motor...

 

[steelespike]

Re: four blade or top water prop?

Your better off with a manual jack plate.Set it up so you can lower the plate below the bottom or raise it above.Usually end up slightly above.
It may be difficult to hook up the remote controls.