ORIGINAL: JimCasey
I'm not a fan of a crosslink between 2 water rudders, but if you DO use one it should be almost impossible for it to drag on the water surface at liftoff. If the tail of the float even TOUCHES at rotation, something is rigged wrong. If you are forcing the tails of the floats into the water deeply enough to drag the cross link, you're dragging the water rudders and probably making enough drag you'll never get airborne anyway.
BIG SNIP
I agree with your theory. However, life does not always obey theory. In my case the plane had ample power to fly fine with the floats. On takeoff it would get up on the step but when rotation occured, first the water rudders would drag and then the cross link would really slow the plane below lift off speed. I removed the cross link and it was fine. I could have solved the problem by a larger engine.
I will admit that this is a marginal case and that is why I said if he had ample power.