What do A/R Planes® REALLY do?

Before we can figure out what an A/R Plane® does we need to figure out what’s going on with any single engine boat.  To help understand what’s happening, imagine that you are suspended in the water behind a boat which is running along on a plane. Most boats use a right-hand  (viewed from the rear) rotation propeller with the centerline of the prop shaft 3 to 6 Inches below the keel of the boat.  Since the prop is usually 13 to 15 inches in diameter, each blade sweeps from left to right across the top of it’s rotation anywhere from even with to 3 inches above the keel.
From our vantage point, we can see the water on the top half of the prop’s rotation is very disturbed and full of air. This affect is caused by the hull and the upper part of the Drive which passed through the water just ahead of the prop.  The prop is now trying to bite into this frothy mixture.
Conversely, the water on the lower half of the prop’s rotation is relatively undisturbed and contains much less air.  For lack of better terminology, lets call the water on the top soft and the water below the prop centerline hard.  Now there are varying degrees of  soft and hard  depending on about a million things including the shape of the bottom of the boat, steps, strakes, pads, etc. and the relative height or "X" dimension of the Drive to the keel.
Nevertheless, the general principle is going to hold true!
Recall that for every action there’s an equal but opposite reaction.
From our vantage point - imagine that prop blade sweeping from left to right across the top of its rotation through  soft water.  The blade exerts a force in a clockwise direction against the water.  The reaction to that force is a counter- clockwise force on the drive.  Since this is relatively soft water which can move out of the prop's way, there’s not much resistance and therefore not much torque reaction.
But what happens to our blade when it sweeps across the bottom of its arc?
The water is harder and provides more resistance. It doesn't move out of the way easily. The result is more torque reaction on the Drive.  If the water offered the same resistance all the way around - each blade’s force would be exactly offset by the opposing blade’s force in the opposite direction (the opposite side of the arc).
The effect of sweeping through hard and then soft water produces a torque reaction on the drive. Since the drive is attached to the boat  - the end result is the boat wanting to rotate, or lean to the left - the more you stand on the gas - the more the prop pushes on the water, the more lean you get with the hull.  Kind of like a big Torque Wrench attached to the center of the transom - with the jolly green giant pulling on it trying to "loosen" the boat!

Most boat builders know all of this - that's why you will see them place the helm and battery on the right side where their weight counteracts the torque reaction of the boat. They also know the shape of the hull and the hydrodynamic lift it produces has a major effect on whether you feel this torque reaction or not.  But, if you get the boat in rough enough conditions to have the hull leave the water (eliminating the hydrodynamic lift) - with the prop still submerged and the power on, you’ll certainly notice the effect - the boat always wants to land on it’s left chine.

Let's change our vantage point.  Imagine we are suspended ABOVE the same boat.  Our driver steers by pivoting the Drive on a king-pin just behind the transom.  Notice that the prop is some distance behind that pin. Remember that the prop blade sweeps into the hard water below the prop centerline and produces a torque reaction.

The prop is trying to pivot the Drive to the right around that pin.  In other words, the Drive is being pulled into a right turn position. The driver must countersteer to the Left in order for the boat to track straight. The greater the distance from the pin to the prop - the more leverage the prop has to pivot the Drive. Drive extensions which increase this distance make this effect worse because they increase the prop's leverage.  

Outboard owners are familiar with this effect as they don’t have Power Steering to help them overcome it.  

Up until now it has only been  possible to mask this effect by forcing the Drive into a left turn with a "torque" tab on the skeg. However, we’re not really fixing the problem, just covering it up like a Band Aid. The Price to be paid is an increase in drag. The Stock torque tab that comes on many drives is mounted to the anti ventilation plate, which is either out of the water, or in such soft water that it has no effect. 

Enter A/R Planes. 

A/R Planes are mounted low in the hard water so the effect they have is much more pronounced. They are mounted below the propeller shaft giving them a leverage advantage on the propeller and the hull. The "Flaps" on the A/R Planes were designed to provide an anti rotation reaction to the outdrive without a speed deficit. They counteract the propeller torque in 2 axis' which levels the boat, as well as correcting torque steer. Their design is a result of countless hours of R&D on several boats, which has afforded a product which does just enough to counter the forces normally seen on these types of craft, without a loss of top end speed.

Remember our original question?  What do A/R Planes® do? Now we can answer it! A/R Planes® cancel all these torque reactions by generating a counter torque on the Drive.