Hi Bo,

PAF in Germany has different sized floats.
http://shop.strato.de/epages/6131678...ries/Schwimmer
I think, "Schwimmer900" or "Schwimmer GfK 900" is o.k. for F3A.

If you are interested in details you could contact Michael Kroeger from FAG Kaltenkirchen, a well-known club in germanys F3A-circus. As far as i know Michael organized every year an F3A-W-Contest (W means water).
[email protected]
Picture 15/83 shows some F3A-Planes with floats from last contest.
http://fag-kaltenkirchen.de/album-wasserflug-2014-1/