For a certificated land pilot, 90% of the seaplane rating is
how to taxi, sail and dock, beaching, and the rules of water
navigation. Yet no seaplane instructor would allow a
student to practice solo in the seaplane

Then you'd agree that the ability to taxi a land plane (on land) has
little bearing on the ability to taxi a seaplane (on water). One
without the skills to solo a seaplane could very easily have the skills
to taxi a land plane (or even fly it).

One without the skills to fly any kind of plane could still have the
skills to taxi a nosewheel landplane safely solo (but not have the
skills to taxi a tailwheel landplane safely solo).

This gets down to instructor judgement, and the type of plane (sea,
land, nosewheel, ski) makes a difference in what would be considered
good judgement.

Jose
--
Nothing takes longer than a shortcut.
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