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Scott
Strickland of Bonita Springs, FL asks:
I
am interested in why Nordhavns have a wing engine. In looking
at other manufacturers, they either do not offer one, or do
not recommend one.
Jim
Leishman responds:
Most
Nordhavns have been equipped with a wing engine. This is a
system which we developed and installed in our first NORDHAVN
46 about 13 years ago.
While
many comercial vessels operate world wide with only one engine,
most have competent engineers aboard and are well suited to
deal with problems with their propulsion system. Aboard many
yachts, the crews are less mechanically inclined and might
have trouble with a significant repair at sea.
The
wing engine operates independant of the main engine. It has
a separate propeller shaft and propeller, electrical system
and battery, a seperate fuel tank into which only fuel that
has passed through a water separator and 2 micron filters
can enter (it has no deck fill). Virtually any problem that
might render the main engine, transmission, shaft or propeller
inoperable, will have no effect on the wing engine.
The
wing engine has the ability to bring a disabled vessel to
a destination where machinery can be replaced or repaired
- or help can be rendered. The wing does have limitations.
It will have a hard time maintaining headway in any winds
above 20 knots however I've never seen an auxillary propulsion
system that will perform as well. In calm water the wing will
push the vessel along at about 5 knots and the alternator
can maintain the ship's batteries and allow continued used
of all electronics.
For
instance, if on our last leg (Cape Verde to Barbados - 2,100
miles) we ran over heavy debris or entangled our propeller
in a discarded ship's hauser that damaged and rendered our
running gear inoperative, the NORDHAVN could have continued
on with the wing engine at speeds of around 4 knots instead
of 6.5 knots. Without the wing engine - a thousand miles from
land - a salvage tug would have to be called thus generating
a salvage claim which could cost tens of thousands of dollars.
Or,
say a fuel filter suddenly clogged and shut down the main
down at a dangerous entrance to a harbor or anchorage, with
the twist of a key the wing could be started and propulsion
could be maintained without hesitation. The alternative task
of clearing the filters, repriming the engine and starting
- all short handed - could allow the boat to wreck and be
destroyed and effectively put the lives of the crew at risk.
Alternate
get home systems usually depend upon a belt or chain drive
from a generator driven hydraulic system. The problem here
is that it takes a huge generator to pull enough power from
in order to effectively spin the main propeller. Also the
tasks of installing the chain or engaging the belt all take
time. In a hot engine room when you don't have time, this
can be a big problem. Providing an alternate method of spinning
the main propeller addresses only the issue of an engine problem.
If the problem is the transmission, the shaft/coupling or
a damaged or fowled propeller, this system will prove worthless.
I personally think you have the greatest risk with the running
gear - everything aft of the engine. This is probably where
a failure will be.
The
wing engine can also be used to maintain directional control
and headway during fluid checks of the main engine when shutting
down is necessary.
The
wing engine adds less than 3% to the cost of an average equiped
NORDHAVN 40 and most people consider it a good value, good
insurance and good peace of mind.
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