Cantide wrote in message . ..
On Thu, 18 Mar 2004 23:25:23 -0500, "Jim and Becky"
wrote:

I saw a comparison in a boating magazine last fall.
I didn't get a chance to read it all but essentially a new boat was offered
in Inboard or I/O configurations.
It was perhaps a 28 foot Regal or Rinker twin screw.
Same engines yet the I/O had a top speed 10 mph higher than the straight
inboard.
Does anyone remember this aricle? I believe it was on the front page.
Is this difference in speeds common and why?


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

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.