Originally Posted by
megan
The term seaplane covers both float plane and flying boat, at least in all my references.
This is a difference between US and British usage.
For aeroplanes that land (?) and take off from the water, British English has no single common term: they are EITHER "flying boats", OR "seaplanes"; "seaplane" means what US English means by "float plane."
US English has a common term, "seaplane", for aircraft operating from water: they are either "flying boats" or "float planes".
So, in British English, the Maia/Mercury composite was a seaplane on the back of a flying boat; in US English, a float plane on the back of a flying boat.
I was brought up on British usage, but I think US usage is preferable, since a common term for water-based aircraft seems like a useful thing to have. I don't know whether amphibians are also included under "seaplane" in US usage, or ekranoplans, come to that.