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On Thu, 12 Oct 2017 11:17:07 -0400, wrote:

Here's a real world example of the diesel vs gas engine trade off. Our
old Bertram 33 had a 320 gallon fuel tank which seems like a lot but
it had 454 gas engines which burned 35 gallons per hour. Cruising
speed barely reached 18 knots on a good day. Doing the math, you come
up with a safe fuel range of less than 140 miles, not enough for
offshore canyon fishing in the NY area. Converting to diesel engines,
the burn rate drops to about 20 gallons per hour, and cruising speed
climbs to 23 knots or so, for a fuel range of around 300 miles. That's
a big difference in the capability of the boat and has nothing to do
with the price of fuel or reliability.

That must be one heavy sommich if 2 454s only get you 18 MPH.
The guy around the corner has a 36 (Donzi I think) with 2 250s on it
that will cruise in the 30s burning a combined 25-30 GPH or so (a
whole lot more at WOT tho)

===

A Bertram 33 is a much different boat than a Donzi: Heavier close to
20,000 lbs; Beamier; Windage from a full flybridge with enclosure;
Full cruising interior.

It would do 25 kts wide open with half fuel but I was concientious
about keeping the RPMs at no more than 3200 or 3300.

The whole point of my comparison excercise was to show that increased
fuel range with diesel is often the deciding factor as opposed to fuel
cost savings.

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