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The engine that drives your bareboat - be it outboard,
gasoline inboard or diesel - is fundamentally like its counterpart in a motorcycle, car
or truck. Indeed, the larger marine diesel versions of these
automotive power plants are frequently built around the
very same engine blocks. But the engine propelling your bareboat creates
unique demands.
Boat engines are run at nearly full speed as much as
90 per cent of the time. This is because an engine produces
its greatest power in the higher range of revolutions
per minute, or rpm's - and far more power is needed
to push your bareboat through water than would be needed to
drive a car down the road at exactly the same speed.
Moreover, the two-cycle design used in many outboard
engines operates most efficiently in that higher range
of rpm's.
To cope with the strains of running full blast for
hours, boat engines are made with many heavy parts,
and this added burden means that
the power plants of your bareboat are more than ever dependent on dirt-free
fuel lines and a plentiful supply of cooling water.
Therefore, the routine checking of fuel and oil filters,
although important in a car, becomes an essential step
in preventing serious damage to the engine of your bareboat.
Marine diesel engines, moreover, are constantly being knocked
about as a boat slams into a wake or bounces over wind-driven
chop - and motion and vibration take their toll. The
buffeting that a marine diesel power plant sustains can knock
finely tuned parts out of adjustment, back off important
nuts and bolts, and snap fuel lines. Because your bareboat engines
have this tendency to take themselves apart, a large
portion of your bareboat operators preventive maintenance
consists of nothing more than on occasional trip around
the engine with a screwdriver and a wrench, trying connections,
and tightening things up before some crucial part is
lost in the bilge or damaged.
Your dependable marine diesel engines
Most bareboats are fitted with
long running and reliable marine diesel engines. While these
engines are fitted with the usual operational safety features
and safeguards, it will still require you to take care of
them, to ensure reliable performance during motor yacht charters and sailing yacht charters.
Marine diesel engines are heavier than petrol engines and produce
less horsepower in relation to weight. However, they do have
some very important advantages... there is no electric spark
required to fire a diesel engine, as it relies on very high
compression of the fuel to attain combustion...also diesel
fuel does not have the same explosive potential as petrol
and is very much safer to use.
Before starting your marine diesel
- Check engine oil and transmission oil levels. This
check must be carried out first thing every morning, before
you start engines and while the engines are cold. The location
of these check points will be shown to you during your bareboat briefing.
Only top up the engine oil if the level is below the minimum level
mark... never over fill the oil as this can damage the
seals in the motor.
Under normal operating conditions the engine and transmission
oil should not require replenishment during a bareboat yacht charter...
Should unusually heavy oil usage or loss occur, advise your
bareboat charter operator by radio. Do not start or run the engine
if obvious, abnormal oil consumption becomes apparent.
- Check the fresh water system. The fresh water system
is filled through the cap on top of the expansion tank...
generally located at the front of your diesel engine. You need to
maintain this level to within ½ inch (10mm)
below the top of the expansion tank. This tank and filling
point will be pointed out during your bareboat briefing.
- Tie the tender up short - make certain there is
no loose rope in the water that could foul the propeller.
To start marine diesel engines
Before
starting ventilate the engine space... Explosive fumes from
all sorts of sources can collect in the bilge of a bareboat.
Make sure that the area around the engine (which can get hot
and often has sparks involved) is ventilated before starting...If
your bareboat has a blower, (a fan in the engine compartment)
run it for five minutes and make sure that the cabin of the
boat has been open for awhile, then check below for any gas
or fuel smells before starting the engine.
To rid the bilge of any dangerous fumes, an electric bilge
blower - placed close to the engine compartment's exhaust
vent - should be operated for five minutes before starting
up the engine and for a similar period after refueling.
Procedure on starting a marine diesel
- Gears in neutral
- Throttle lever back
- Turn on ignition key
- Press - on starting button, until engine fires - release
button.
- Set throttle lever to warm-up (idling speed) at 700-800
rpm
- Warm engine to 170 degrees fahrenheit (76° celsius)
before load is applied.
Once your engine starts, look for water: Most inboard
diesel engines have water-coolant and exhaust exit holes or pipes
visible from on deck... These are often in the transom. When
you start the engine, confirm that water is coming out of
the exhaust (usually a slow, pulsing flow) - this means the
cooling system is working properly.
When manoeuvring, never go from forward to astern
or "vice-versa" without pausing in neutral
for a second of two. Changing gear straight through the box
while your engine is running above idle speed can damage the
gearbox.
If
your engine is showing a high operating temperature you
know you have a cooling system problem (often a plastic bag
can be sucked into the intake)... If the temperature gauge
is telling you there could be a problem avoid operating your
engine at maximum throttle - doing so may cause overheating
and you will have to stop the engine.
Watch the tachometer if you have one, and keep the rpm's below
the engine's safe operating speed, until you determine the
cause. If you have twin marine diesel engines shut down the problem engine.
Procedure to stop
- Throttle levers right back
- Gears in neutral
- Idle engines for 2-3 minutes allowing the engines to start
cooling.
- Depress stop buttons and hold until engines stop, and
buzzer sounds.
- Turn off ignition keys -buzzer stops.
Overheating
Marine diesel engines are usually cooled
by sea water... A pump (generally) mounted at the front of
your engine, pumps seawater through the engine manifold, etc.
A marine diesel does not run for long if this process is interrupted
in any way. The most common problem encountered, when an "overheating"
signal is detected is failure of the engine seawater
pump impeller or blocked water intake. An impeller
is easy to replace and spare impellers are kept on-board
charter boats.
The first warning of your marine diesel overheating will be the
engine alarm sounding or the needle on the temperature gauge
rises. You will have already heard this alarm, when starting
and stopping the engine. At the time of your bareboat briefing you will
be shown that this alarm is in satisfactory working order.
If you hear the alarm, and it is safe to do so, immediately
switch off the engine and investigate. The consequence of
a badly overheated marine diesel engine is at best a blown head and more
commonly a cracked head...both expensive.
Damage to a marine diesel engine through overheating is almost
always a result of operating negligence.
Engine instruments
- Revolution Counter - RPM. This allows you to select
the speed or RPM (revolutions per minute) your engines will
run.
At your bareboat briefing you will be advised of the correct RPM
for your boat, do not exceed these RPM during bareboat charters...
Running your engine over the recommended RPM is not efficient
and your engine will not burn off the increased fuel intake.
This means you'll be exhausting unburned fuel at increased
diesel costs, with little or no improvement in speed.
This revolution counter also generally includes an hour
meter which tells you how long your engine has run... These
hours are noted at the beginning and end of each charter
as 'used' engine hours determine the maintenance checks
and services required.
- Oil Pressure Gauge. If either gauge is not registering,
or only showing very low pressure... notify your charter
company.
- Water Temperature. With engines operating at a
normal cruise speed (RPM) your water temperature gauge should
read approximately 180-190 F° (82 - 88 C°) (or as
advised at your bareboat briefing).
At temperatures over this start to pay careful and continual
attention to your instruments and bring your engine speeds
back.
Once the temperature of either engine gauge goes over the
designed running temperature you should hear the warning
buzzer sound...If safe to do so, shut down your engine
immediately... notify your bareboat charter company.
- Ammeter. This tells you the rate of charge going
into your battery banks...if any ammeter is not charging,
notify your charter company.
- Fuel Gauge. Your fuel gauge should accurately reflect
the overall fuel position - at the start of each charter
your fuel tank/s will be full - and will be refilled on
completion of your charter.
The sturdy marine diesel
Diesel marine engines have a well-earned
reputation for running smoothly with less care than other
types of power plants. There are two reasons. Most marine diesels
are built to heavy-duty specifications that help to ensure
their durability; typically, a 50-horsepower diesel like the
one below will run four times longer between major overhauls
than a gasoline engine of equivalent power. In addition, a
diesel engine is designed to operate without either a carburetor
or an electrical ignition system. Consequently, it has fewer
parts to wear out or break down.
Taking the place of a carburetor is a device called a fuel
injector, which sprays precisely measured charges of vaporized
fuel oil into each cylinder through a fine-gauged nozzle.
The fuel vapour enters the cylinder just as the piston reaches
the top of its stroke, compressing the air inside. This compression,
which may reach as high as 500 pounds per square inch, raises
the air temperature in the cylinder to about 1,000 F - well
above the flash point of the fuel. Thus no electric spark
is needed to ignite it
Despite it's rugged construction, the diesel is not entirely
maintenance-free...your charter boat operator will see that
crankcase oil is changed at regular intervals, as prescribed
in the engine manual. Drive belts for the alternator and water
pump will be checked for wear and proper tension following
the procedure shown in the diagram... Adjusting Belts below.
The cooling system must be kept brimming with fresh water.
In addition, the fuel system (outlined in blue, below)
must be serviced periodically. Otherwise, specks of dirt and
sediment in the diesel oil may clog the narrow channels in
the fuel injector and nozzles.
To guard against clogging, a set of primary and secondary
filters in the fuel lines trap minute dirt particles.
The primary filter also removes water droplets suspended in
the fuel - the result of moisture condensing inside the fuel
tanks. This water accumulates in the bottom of the filter
housing, which should be drained regularly during periods
of normal engine use. In addition, after every 200 hours of
operation, the filtering elements in both the primary and
secondary filters should be replaced and the fuel pump cleaned.
In
marine diesel engines, the fuel system (blue) and the primary filter (bottom
left) extracts the condensed moisture and some dirt from the
fuel.
A pump then drives the fuel through a secondary filter that
removes any remaining dirt particles, and pushes it on to
the fuel injector.
The cleansed fuel is led through the injection pump, which
channels it in carefully timed, measure doses to the injector
nozzles. The fuel injector's overflow line carries excess
back to the tank.
Adjusting
belts
Belts running off the drive shaft power the cooling
and electrical systems. If the belts are too loose, the system
will not work efficiently; if too tight, they will wear out,
crippling the engine. Ideally, a belt should have from one
quarter to one half an inch of play (dotted line) when pressed
firmly with a thumb at the midpoint between the pulleys. This
thumb test should be performed after every 50 hours of engine
use, and the belt adjusted to the correct tension... shown
at right.
If
the electrical system's belt is slack, it should be tightened
by moving the alternator along the slot in the mounting bracket.
Loosen the mounting nut with a wrench and then take up the
slack in the belt by prying the alternator away from the engine
with a long sturdy tool, such as the wrench shown here. Secure
the mounting screw and test the tension again to be sure that
the adjustment is adequate.
The sea-water pump can be moved in the same way to adjust
its belt.
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