Yeah, the H900 says up to 43', but the specs are really very minimal.
They estimate the "normal working load" at 225lbs and the normal draw at 55 amps. This
winch, IMHO, is much too small for a Passport 40.
My Concept 2 draws about 80 amps at the same load, about 150 amps with a 880lb load, and up to 250 amps with a (momentary) 1,760lb load. And, I don't think this
windlass is too big; rather, it's just about right if used properly.
As you know, proper use of a windless is for lifting the
rode and
anchor, not for pulling the boat into a strong wind/current and pulling the
anchor free of the bottom. You have correctly calculated what the "proper load" could be, counting chain and
anchor.
However, in the real world windlasses ARE sometimes used to pull the boat up to the
anchor, expecially in emergency situations. This can create loads way beyond the "normal" load. With a minimally-sized
windlass, you'll be popping breakers and/or damaging the
windlass in such situations.
Again, IMHO, the Passport 40 is a quality boat. It deserves a quality (and hefty)
windlass.
By the way, you could save some weight or increase holding power by going with G40 HT chain rather than BBB.
Bill