View Single Post
Old 04-12-2021, 09:57 AM   #11
Senior Member
Join Date: Apr 2008
Location: Moultonborough
Posts: 634
Thanks: 4
Thanked 204 Times in 129 Posts

Originally Posted by BroadHopper View Post
Thank you for the clarification of minimum steerage. Although I have been told to slow down, a deep vee boat does not maintain a straight path at 6 mph and less. The boat would wander left and right. Officers thought I may be imbibed.....
My own boat does that when the throttle lever is barely in gear. A quick search just now tells me this is called "low speed wander." From this reference:

"Roy Ellis, senior project manager of product development for Monterey Boats, said itís the result of water rushing aft along the sides of the boat and then collapsing into the hole behind it.

This creates swirling vortices of water that exert suction on each side of the transom, pulling the boat back to the right and then left, Ellis said. Prop torque only exacerbates the problem.

Inboard boats typically donít suffer from low-speed wander because their rudders have enough surface area to overcome the tendency to veer off course.

Sterndrives and outboards donít really have much of a rudder, relying more on directional prop thrust. At low speeds, prop thrust is not as effective as a rudder for maintaining a straight course. And thatís why sterndrives and outboards are more prone to low-speed wander."

Drives with two opposite-rotating props minimize or eliminate the effects of prop torque. I learned long ago that I could keep a mostly straight course at headway speed by anticipating the swings with small countering swings of the steering wheel.
DickR is offline   Reply With Quote