All cubs with scale aileron setup do suffer from adverse yaw to a good degree and will benefit from an active left thumb as gxc mentioned or a bit of aileron to rudder mix. Now as politically incorrect as it is to use this mix in reality most flyers do not use the rudder appropriately for all turns even when they do occasionally.

Now with a float plane this situation is amplified even more, try using a little aileron to rudder mix, perhaps around 20% and this will give you an airplane of entirely different character and flies much more prototypically In other words nicer.

John