Yes.

Do many states on the east coast do that?

Some do. Some tax more, some less.

The national marina operators association is lobbying the US
government to get _all states to charge 4% property tax on
boats, whatever a marina association's interest in taxing
might be.

Do you have to be in their waters for a certain period of
time for the tax
to be levied?

You have to be found there by the tax man, who prowls around
marinas, creeks and anchorages looking for boats to tax.

--
Joe

Joe Kovacs
SV Sea Breeze