ORIGINAL: JohnBuckner
Putting the step ahead of the CG will not provide those pretty float plane lift offs we all love so much and in my opinion will only agravate your t/o directional stability. This works in exactly the same way that a land plane with taildragger main gear when the wheel footprint is too far forward and the result is directional instability. The area immediately in front of the step when on the step is in effect of the wheel footprint. Move it further forward and always the result is instability.
John
Unlike a wheel plane, where the center of pressure is the bottom of the wheel, the initial point of water contact and total wetted area of a float is variable depending on the angle of attack of the float. You can change the point of contact and thus the center of pressure and yaw stability of the plane on the water by using the elevator to change the angle of attack.
In this case, if the downthrust (or excessive negative incidence in the float) is forcing the nose of the float into the water, the point of contact will be far in front of the step, causing the instability. If that is the case, moving the float forward, thus increasing floatation in front of the CG, can allow the point of contact to move rearward to a more normal position. I've done it on many trainers and it seems to help.
Jim