Hi jabberwok
Sorry, I don't have a plan view of the float installation. I did, however, scrounge up another pic of a DH.60G Gipsy Moth on
amphibious floats. It's in the book "Otter and Twin Otter," by Sean Rossiter.
The amphibious installation consists of one float mounted on the aircraft centerline, with a small outrigger float under each wing. Here's what the photo caption has to say:
The DH.60G Gipsy Moth G-AADV in flight. This aircraft was the first amphibious Moth, delivered to Mr.XXX in February 1929. Short Bros. of Belfast supplied floats for early Moths, including those operated by OPAS. The retractable wheeled gear pivoted on a steel rod running lengthwise through the single centerline float.
The float in this picture does have a water rudder, but it's so small that it probably served more as a decoration than anything.
OPAS by the way, was the Ontario Provinial Air Service. They used aircraft for forest fire spotting and suppression, beginning about 1925 or so.