T&T: fuel efficiency

[Robin Brueckner]

"... Is it not correct to say: The smaller the wake, the more efficient
the hull? (Assuming same waterline length and speed...."

That is potentially an indicator ..but what does it mean in terms of
power? Is that a 1% , 10% or 20% difference in power? My own question has
always been how much HP does it take to create moderate size wake
waves...Do they really reflect power consumed very accurately?...for
example I can rock my whaler side to side and make, let's say, 8 inch
waves...how much HP is that 1/10??  I have no idea, but I'm sure it's
pretty darn small...And I can produce waves over one foot with an
outboard developing about more than four or five HP....that's pretty
insignificant in a 40 to 50 foot hull comparison......but I really don't
know the significance of those comparisons....

Even when the wakes and speeds and hull lengths are similar, the power
consumed may be quite different at the same speed. Arild's experience
with long narrow hulls mirrors my own experience...a low beam to length
ratio generally means clean running. Another variable is the following
wave in the wake....how does that relate to the bow wave which is likely
the one we are most discussing here...is one more indicitive of power
consumed than the other???

My Dad always believed it was more efficient to run our old Matthews with
a clean fish tail..no dragging water behind...Well it wasn't until I
studied engineering in college that I began to realize the bubbling forth
in the wake behind the boat was not solid water and gradually disappears
with speed increase so his generalization no longer made sense. Another
way to say it is that the size of the wake wave did not appear to change
as the frothy to clean wake is achieved..with my current boat speed
increases in that range appear to create larger wake waves..

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