Marine Advisory Program offers
boaters tips to conserve fuel, save money
June 23, 2008
Homer, Alaska - Whether you are a commercial or sport fisherman,
recreational boater, charter skipper, water taxi or tour operator,
saving money on your vessel fuel bill can be as easy as slowing
It can also be as complicated
as deciding whether to replace that tired old fuel-guzzling engine,
or even the entire vessel.
"How much a boater saves
on fuel is determined by many factors," said Terry Johnson,
a Marine Advisory Program agent and boat owner based in Homer.
He also has written articles on fishing vessel maintenance for
a popular trade magazine.
"While there are some
general steps all boaters can take, maximizing fuel savings comes
down to a number of personal decisions about a specific vessel.
No two vessels will be exactly alike."
To help boaters weigh their
options, Johnson recently prepared a list of steps that can help
lessen the impact of high fuel costs.
First on his list is simply
slow down. Seems obvious, but the savings can be dramatic. For
vessels that plow through the water-that is, they displace water
rather than skim over the top-even a small decrease in boat speed
will save fuel on most boats. Johnson said published data indicate
that reducing power as little as 10 percent from full throttle
will lessen fuel consumption by 20 percent. Back off the throttle
to the point where the stern wave starts to flatten out and the
savings will be greater. Reducing speed by just one or two knots
can cut fuel consumption by 30 percent to 50 percent.
Running your diesel engine
at its most efficient rating also will save fuel. Johnson said
diesel engines are most efficient at 80 percent of maximum continuous
rating (MCR). That means they produce the most power for the
fuel consumed. But be careful, most fishing vessels are over-powered
and achieve their most efficient vessel speed at a power setting
well below optimum engine speed and load. To get the most nautical
miles per gallon you'll probably have to run your engine at a
speed slower than its most efficient setting. Running too slow
for too long, however, could damage your engine.
Things get a bit more complicated
for vessels that plane or displace little water. These boats
rely on skimming the surface; slowing too much causes the vessel
to ride lower in the water, lowering fuel efficiency. Johnson
suggests using a fuel flow meter, or keeping accurate records
of gallons burned divided by miles traveled at different revolutions-per-minute
(rpm) until you find your vessel's most efficient engine and
Other tips for beating the
- Exhaust. Exhaust from a well-maintained
diesel engine is virtually invisible. Black exhaust means the
engine is overloaded, starved for combustion air, or has worn
injectors. If the exhaust is white, there is an injector or valve
timing problem, burnt valves, or bad gaskets allowing coolant
into the cylinders. Blue exhaust indicates oil in the combustion
chambers from worn rings or valve guides, or a turbo seal failure.
All of these problems decrease engine efficiency and increase
- Prop. When the boat is out
of the water, check the prop for bent blades, dings, or eroded
edges that cause fuel-robbing cavitation. While underway, check
the propwash for excess turbulence and bubbles that suggest a
prop that's too small or has too little pitch. And check your
exhaust stack for black smoke that would suggest overloading.
Use your tachometer and pyrometer to ensure you have the right
prop. This can change as the use of the boat changes or it gains
weight or resistance from additional equipment or modifications.
The engine should quickly reach rated rpm and exhaust temperature
should be within manufacturer's specs; if not, the prop is too
big or has too much pitch. If the engine exceeds rated speed
or exhaust temperature is too low, you may not be wasting fuel
but you could be causing long-term harm to the engine due to
carbon buildup and cylinder glazing. Use a computer prop sizing
service to ensure you have the right diameter, pitch, blade area,
and prop configuration.
- Hull. Marine growth on the
bottom of a boat saps power and wastes fuel. Get the weeds and
barnacles off and keep them off with proper antifouling paint.
The smoother the paint, the less friction, so find the right
paint for your hull. Sponsons, struts, sea chests, keel coolers,
transducers, and stabilizers all increase hull drag. You probably
need those more than an extra fraction of a mile per gallon,
but if there's something below the waterline you don't need,
get rid of it.
- Electrical system. Do you
need to run a diesel genset around the clock or can you use batteries
and an inverter for your "hotel" power? A larger alternator
on an underloaded main engine may produce electricity more efficiently
than a standalone generator. Can you cook on an oil or propane
range rather than an electric one? Consider adding a wind charger
or solar panels to reduce the fuel cost of electricity.
- Steering. You burn fuel to
push your boat through the water, but if it's not going the shortest
distance to your destination you may be wasting fuel. If there's
play in your steering, adjust it to eliminate as much as possible.
A good autopilot can steer straighter than any helmsman. Even
if you have a great autopilot, watch your wake and you may see
that you're zigzagging through the water. The pilot's control
head probably has adjustments that change steering parameters
and allow you to minimize delayed or oversteering in calm conditions.
Modern units even have a no-drift mode that compensates for wind
- Plan your trip. Remember when
vessels used to depart on the tide? It was not so necessary with
big engines and cheap fuel, but now routing to take advantage
of tides, currents, and predicted winds can save money. Remember,
the shortest distance between two points on the water is not
necessarily a straight line. Tide and current tables, and oceanographic
current charts, can indicate ways to get a boost from nature.
Good weather forecasts help you avoid headwinds or delaying sea
conditions, and also suggest chances to get a boost from tailwinds.
- Vessel weight. More important
on a planing or semi-displacement vessel, weight control reduces
the amount of power needed to achieve a given speed. Boats quickly
fill up with supplies, gear, and spare parts. On short trips,
it may not be necessary to run with full fuel and water tanks.
Use trim tabs or shift passengers, gear, and ballast to achieve
proper vessel trim. On displacement boats, additional weight
may improve seakeeping and in some cases may actually improve
fuel efficiency by helping the boat proceed more directly through
- Keep good records. You only
know whether you're making an improvement (or making things worse)
if you have good numbers on vessel performance, both before and
after changes. At every fuel-up you should record fuel replaced,
operating hours (from your hour meter or engine hour logbook),
and if possible, distance traveled. Other observations such as
changes in coolant and exhaust temperatures, oil temperatures
and pressures, and speed over the ground (as indicated by GPS
or LORAN readings) should be logged.
- Do the math. Fuel is only
one of the costs of your operation. Capital expenditure (the
price of new equipment), and the value of your time and that
of your crew, are also costs. The cost of a solution, such as
buying a new engine or even a new vessel, may be greater than
the savings that could be realized. As fish prices, fuel costs,
regulations, and other factors change, it is important to recalculate
On the Web:
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Boating Fuel Efficiency Resources
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