Small Boat Journal is sorely missed.
Not quite what you asked for, with focus un un- and low-powered boats:

Messing About in Boats
http://www.messingaboutinboats.com/

Sal's Dad

I am looking for a good boating magazine that is focused on small
powered boats (14-ft to 22-ft range).

I believe there used to be a good magazine called "Small Boat". But it
has been transformed into "Boating World", and it is no longer as good
as it was for readers who are interested in small boats, or something
like that. Is this really true? I cannot find "Boating World" magazine
in the local book store. Therefore, I cannot tell if it is any good.
And the boating magazines in the book store seem to cover only the big
and luxury boats.

Any good boating magazine that has good coverage for small boats?

Thanks.

Jay Chan