Prop torque

[DeepCMark58A]

When I bought my Alumacraft Deep C it had a mid 60's Mercury 350 35hp motor, the prop torque was evident. I repowered with a Mercury 400 45hp and there is no evident prop torque. Is it possible that with the 45hp motor it gets up higher on plane thus somehow eliminating the torque? Both motors were run with 2 blade props. I need to add that even when I ran the 3 blade prop on the 400 there still was not prop torque.

 

[fhhuber]

Could just be that the trim tab under the anti-vent plate and behind the prop is adjusted better.

 

[jimmbo]

Could be the trim tab. Could also be the trim angles of the engine are different. What about the skegs, straight and all there?

 

[DeepCMark58A]

Yep skegs were both there.

 

[Fed]

How was the prop torque evident?

 

[DeepCMark58A]

You had to turn the the wheel it keep the boat going straight. The Alumacraft Deep C is a realitivly light boat.

 

[Fed]

You had to turn the the wheel it keep the boat going straight.

That's not caused by prop torque, prop torque tries to twist the hull normally laying to the Port side with a right handed prop.

Steering problems are caused by trim and motor trim tab settings.

Too much negative trim increases the thrust on the right hand side blades causing the boat to steer Starboard.
Too much positive trim increases the thrust on the left hand side blades causing the boat to steer Port.
Both are easily fixed with trim adjustment.

Engine torque causes the motor to turn Starboard easily fixed with trim tab adjustment.

Highly mounted motors can also suffer from a paddle wheel effect to the Starboard & lack of water pushing on the trim tab.

It's a real can of worms when you factor in sideways & longitudinal weight.