But most seaplane flight schools don't really aim to produce "competent seaplane pilots". The entire seaplane instruction industry revolves around weekend-long 7-flight-hour crash courses. Yes there are a lot of things that go into being a competent seaplane pilot, but are all those things really ever covered in 2 day courses? Remember, there are also tons of things that go into being a "competent landplane pilot" such as how to fly around mountains that are hardly ever taught in landplane flight schools...
I do believe that a competent land plane instructor with minimal float experience who's trained for and passed a CFI-ASES checkride to teach a landlubber enough about float plane flying to pass the ASES private checkride but my point is that's so very far from producing a competent floatplane pilot.
In America at least, theres no such thing as a CFI-SES rating. All you need to instruct in a SES is a single engine CFI and a SES commercial. Additionally, to instruct in a MES, all you need is a MEI and a MES commercial.
Anyways, what I'm basically trying to say here is that, in my opinion, if you can do it, and you can teach, then you can teach doing it.
Since I hold a current CFI certificate, that proves I can teach. Since I can land a C-172, I can teach landing a C-172. Since I can do an approach down to minimums, I can teach doing approaches down to minimums. I don't need 10,000 hours of either of these activities in order to yeach them properly.
With that in mind, I feel that as long as I can land a C-172 on water, I can teach landing a C-172 on water. As long as I can taxii a C-172 on water, I can teach taxiing a C-172 on water.
Right now I have a tailwheel rating and about 5 hours of tailwheel time. Can I instruct tailwheel students? Of course I can. Personally, I don't really feel confortable doing such instruction since my tailwheel time was over a year ago, but otherwise I don't see what the pont of having more hours would be.
This is a response to the idea of people thinking anyone with less than a small lifetime of seaplane flying can't possibly teach others to fly seaplanes.