A number of answers.
As launched the S6 had symmetrical floats and sufficient fuel tankage in each to allow part, or all, the fuel to be carried in the starboard float to offset torque if required. Initial tests showed that most fuel would indeed have to be carried there. It was also apparent that both engine and airframe were slightly heavier than estimated and hence reserve bouyancy was looking a bit marginal, and with the addition of extra radiators and more coolant water during development this looked even worse. Finally there was concern that the low nose on the float design, required to minimise drag in the air, could result in ‘nosing in’ on landing. So the longer, higher nose float fitted for the contest was a quick fix designed to deal with all these.
The floats on the S6a, esstentially lengthened S6 type, were a better solution and the those on the S6b were a completely new design.

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