did the plane fly good before floats???? Have you tried lowering your water rudders in flight to see if that makes a difference? If that does it, change the rudders only.
If not, then you really may have two troubles.
My plane, the beauty it is, flies a full 5 mph faster when the tail of the floats are off center 1".
Has your plane been wrecked???
Start by measuring from a marked spot on the bow to the center of the wing/wing strut attach bolt on each side. Use the same location on each side. write the numbers down.(use points that give you the greatest distance, this makes it easier to rig, two people needed!)
Now go from the strut/wing spot to the outside of the stabilizer on each side. Write them down.
Now adjust the fly wires to make each side the same, (1/4 inch is good, some trial and error may be needed).
If the plane is not perfectly strait, you may need to adjust the floats out a widget to get her to fly correctly.
Remember to write down where the final rigging was, or you do it again next year!
george