wrong prop symptoms

river warrior · Sep 24, 2015

I just bought a prop off ebay. Not really sure what the right prop would be for my boat. My motor didnt have a prop when I got it. So I picked one with the same dimensions as one listed on marineengins.com. 10 3/8 x 11 1/2. When I tested it out in the lake I couldn't go faster than 5mph without the motor reving high and what felt like the motor slipping. I took the boat out of the water and checked the prop hub by puting the motor in gear and trying to spin the prop by hand. It did not slip. It actually turned the motor over. I dont think its a spun hub. A gentleman at the dock saw me with the motor problem and told me he had a similar problem with his boat. He bought a different size prop and the problem was fixed. Does my scenario sound like a wrong prop problem. I tried using the prop calculator but it didnt have anything for my motor. 1985 force 50 model 507x5a. This motor is on a 16ft 70inch wide v-hull aluminum bass boat. Any help is greatly appreciated.

kofkorn · Sep 24, 2015

I'd still bet on a spun hub. You really can't tell by trying to spin the prop by hand. You need to mark it and then run it an check your marks.

If it matches one of the props that is on marine engine, you should at least get a reasonable speed out of it.

Good luck.

river warrior · Sep 24, 2015

Thx ive been searching for my symptoms on you tube and only find them on spun hub videos.

KMixson · Sep 24, 2015

I would also bet on a spun hub. You may be able to turn the motor over by turning the prop but that does not mean the hub is good. It actually takes a lot of torque to turn that prop while it is in the water. The faster you try turn it the more torque it takes.