Diesel engines have no secondaries per se, making it
somewhat more difficult to find that sweet spot other
than anecdotally. Many seasoned operators know how
their vessel performs and where that ideal economical
speed lies only because they’ve spent many hours aboard
and many miles cruising. Fortunately, if you don’t have
the benefit of that experience, you can cheat by using a
fuel flow meter. When properly installed and calibrated,
a fuel flow meter provides the boat owner with an
extremely accurate representation of fuel consumption.
In using one, you may find that a difference of as little
as half a knot can have a significant impact on fuel
consumption, and this can allow you to precisely dial
in your sweet spot.
Electronically controlled common-rail engines, whose
operating data include fuel consumption, also can benefit
from this practice.
Get The Lead Out
When it comes to vessel design and construction,
weight control is a subject that elicits considerable
emotion on the part of naval architects and boatbuilders,
and with good reason. In very simple terms, less weight
means less energy is required to move the boat.
For semi-planing vessels, lifting more weight to get the
vessel on plane is simply a net loss. Weight removal in
this speed category equates to lower power requirements
and thus reduced fuel consumption.
Therefore, it makes little sense to carry weight that’s
not needed unless it markedly affects the vessel’s safety
or seakindliness. Making passages with a full load of
diesel and water, for instance, if neither is really needed,
consumes fuel unnecessarily. Likewise, many vessels
accumulate unnecessary or duplicate stores and
equipment that could be left ashore.
In short, lowering the waterline will nearly always
improve fuel economy.
Run With The Tide
Making the most of currents is something that
sailors do all the time. (And sailors no doubt are onto
something when it comes to efficiency; last time I
checked, wind was much cheaper than diesel.) If you’re
planning a voyage and time is not of the essence, it may
be worth timing your departure so that you run with an
ebbing or flowing tide. Tidal data is easily obtainable
from countless sources, both as hard copy and online.
Additionally, diverting your route slightly to avoid a
countercurrent or to take advantage of a current may
yield a net gain, depending on how far out of the way
you’ll have to go and how long you’ll ride “the stream.”
Large commercial vessels do this on a regular basis to
Improving Fuel Economy
OIL PRICES:
NOWHERE TO GO BUT UP?
The price of oil will rebound to more than $100 a barrel
as soon as the world economy recovers and will exceed
$200 a barrel by 2030, the International Energy Agency
predicted in its flagship report published in November.
The developed world’s energy watchdog doubled its
long-term price expectation from last year’s $108 a
barrel for 2030 and assumed oil prices would rebound
from today’s $60 to $70 a barrel to trade, in real terms
adjusted by inflation, at an average of more than $100
a barrel from 2008 to 2015.
The IEA also predicted that world energy demand will
rise an average of 1. 6 percent each year over the next
few decades.—Reported in The Financial Times,
November 2008
decrease overall fuel usage. Certainly, over longer
passages, the effort required to ride a current becomes
more worthwhile.
Given the choice, no mariner would, or should,
intentionally run into a head sea; it’s just darn unpleasant.
In addition to the fatigue and added wear and tear on
the crew and vessel, running into a head wind or sea can
dramatically increase fuel consumption, an effect that can
be more pronounced on a boat whose superstructure,
including canvas, is more substantial. Therefore, if you’re
able to plan your passage or departure time to avoid this
scenario, the voyage may be not only more pleasant but
also less expensive.
MODIFICATIONS, MAINTENANCE,
AND ADJUSTMENTS FOR
IMPROVING FUEL EFFICIENCY
In the previous section, we discussed ways in which
you can modify your behavior to improve vessel
performance. Now, let’s review how you can adjust
and maintain your boat to achieve greater efficiency.
Tune-Up, Please
The following statement may seem obvious, but in
the two decades I’ve worked on boats and managed
boatyards, I’ve become painfully aware of the fact that, to
many boat owners, it’s not: just because the engine starts
and runs, it isn’t necessarily operating with the greatest
efficiency. In fact, there are a variety of fuel-efficiency-challenging ailments from which an engine can suffer
with no overt symptoms.
Crankcase and transmission oil, for instance, fall
squarely in the out-of-sight, out-of-mind category. Using
old, poor quality, contaminated, or improper grade
