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?