Which Prop,..??

Rokomo

Cadet
Joined
Sep 26, 2017
Messages
8
Hello to everyone in this forum-and others. I have a torque steer issue that I wanted to share with you and maybee shed some light on. Here goes-
We have a 17 ft Sea Nymph alum fishing boat. Replaced the under-powered 50 HP/15 pitch prop setUp with a 90 HP/19 pitch motor & prop combination. I ran through several prop calculators and input the boat hull design and carefully estimated the typical weight load, etc and the 19 was the most recommended pitch.
The new motor came with an old-school 2 blade stainless prop in 19 pitch. It runs the boat really good with nice low end torque and decent top end speed, but that prop produced severe torque steer to the right. We changed the prop from the old 2blade to a new Turning Point 3 blade 13.25 x19 and this new prop did not clear the trim tab anode-so we took the anode off the motor and went out with the new prop for a test run. The hole shot was sluggish and it took forever for our motor to get the prop wound up to top RPMs. But the interesting part is-with the new 3blade prop and NO trim tab anode the torque steer completely disappeared. Gone. I could let go of the wheel at 45 MPH and she tracks smooth and straight as an arrow. Could that old prop and the annode be interacting somehow to cause the torque steer, or was it likely just the prop causing it ?????
 

ahicks

Captain
Joined
Sep 16, 2013
Messages
3,957
If you need no assistance with torque steering, the flat anode without the fin will work fine. Seems like too, that there are anodes available with the fin set back a little, to allow for extra prop clearance?

To maintain engine rpm, you have to decrease the pitch when going from a 2 blade to a 3 blade. I have to wonder if the reason you aren't getting torque steer with the 3 blade is because you lost a bunch of engine rpm?
 

Rokomo

Cadet
Joined
Sep 26, 2017
Messages
8
Yes, well, we are now testing a 17 pitch/3 blade with the flat anode. Expecting good results. Thanks for the info.
 
Top