Also Sprach John :

For one thing, the thrust angle of the I/O is parallel to the bottom
of the hull. The inboard is at an angle, so some of the thrust is
directed upward instead of forward.

Dan, your correct, it does have to do with shaft angle. But the one
thing not mentioned is operating cost and ride. The I/O, because of
it's greater complexity, and because it made of aluminum (except the
new Volvo units that are "plastic") will cost more to own over the
long term. Also, the straight inboard will have a much better ride,
they tend to stay in the water when going over most waves, rather than
jumping like I/O's and outboards.

Oh, absolutely. I would NEVER own an I/O because of the mechanical issues
relating to the outdrive. But I don't deny that they are more more
mechanically efficient than an inboard.

Dan

--
Barbie says, Take quaaludes in gin and go to a disco right away!
But Ken says, WOO-WOO!! No credit at "Mr. Liquor"!!

-- Zippy the Pinhead