Ship Manoeuvring
Manoeuvres for rescue of person overboard
Ship Manoeuvres for a Man Overboard
The Round or
Anderson Turn is a maneuver used to bring a ship or boat back to a point it
previously passed through, often for the purpose of recovering a man overboard.
This turn is
most appropriate when the point to be reached remains clearly visible. Both
will require more time before returning to the point in question.
1. If the turn
is in response to a man overboard, stop the engines.
2. Put the
rudder over full. If in response to a man overboard, put the rudder toward the
person (e.g., if the person fell over
the starboard side, put the rudder over full to starboard).
3. When clear
of the person, go all ahead full, still using full rudder.
4. After
deviating from the original course by about 240 degrees (about 2/3 of a
complete circle), back the engines 2/3 or full.
5. Stop the
engines when the target point is 15 degrees off the bow. Ease the rudder and
back the engines as required.
If dealing
with a man overboard, always bring the vessel upwind of the person. Stop the
vessel in the water with the person well forward of the propellers.
The Williamson Turn
John A. Williamson entered the US Navy as a seaman and
later became the Commanding Officer of the USS England. As an instructor
ashore, Williamson developed a series of turns used to bring a ship back on its
own wake after a man fell overboard.
Williamson recommended they teach the turn as a maneuver for man
overboard recoveries during night and low visibility conditions.
Williamson after retirement wrote, “I’ve gotten letters and seen articles where
people have been picked up using (the turn). I don’t have a clue as to how
many. I don’t know whether it’s ten or 5,000. I don’t feel that there’s any
glory to me though. It’s just something I came up with that turned out to be
worthwhile. I don’t think I’m due any glory for it, or any fame or anything
like that.”
The principle behind the “Williamson
Turn” is to return a ship to the exact location where a seaman fell overboard
by using the ship’s wake as a reference point. This requires that a ship first
turn to starboard, followed by a turn to port that is concluded when the ship
crosses its own wake.
This is the most efficient of all the turns till date.
The manoeuvre basically comprises of the following
helm movements:
A wheel over of hard over on any side suitable
To maintain the helm until the course has altered by
60 degrees.
Once this is achieved the wheel is put hard over on
the opposite side
The wheel is kept at hard over until about 20 degrees remain to bring the vessel to the reverse of original course, when the helm is put to amidships
Helm is used to ease the ship on to the reverse
course. (It helps if the original wake of the ship can be seen)
This is the most efficient since without any
navigational aid the ship would retrace her path and go up the course line.
Small deviations are to be allowed for the tide and
current and wind effects. But overall is the best method to recover or to at least
go over the path of the ship.
The above plot is an actual done on board a medium
sized tanker and as can be seen there is very small deviation. Of course the
positions were plotted by GPS fixes. But the position fixing was superfluous.
(MOB position: Lat. 16˚36.2’N, Long. 082˚47.65’E)
Regarding which side to put the wheel over the first
time, a lot has been said about putting the wheel over on the same side as the
man overboard.
Actually the amount of time it takes for a man
floating to pass the stern and the time it takes to raise the alarm and
actually to put the helm over is so vastly different that the man overboard is
very far behind the ship by the time the ship starts turning.
Please note in the case of any turning of the ship to
recover a man overboard – it is assumed that the vessel is at sea speed. Since
at a anchorage/ harbour the lowering of the lifeboat
is much more convenient.
The Scharnow Turn
The Scharnow
Turn is a maneuver used to bring a ship back to a point it previously passed
through, often for the purpose of recovering a man overboard.
The Scharnow
Turn is most appropriate when the point to be reached is significantly further
astern than the vessel’s turning radius. For other situations, an Anderson turn
or a Williamson turn might be more appropriate.
Put the rudder
over hard. If in response to a man overboard, put the rudder toward the person
(e.g., if the person fell over the
starboard side, put the rudder over hard to starboard).
After
deviating from the original course by about 240 degrees, shift the rudder hard
to the opposite side.
When heading
about 20 degrees short of the reciprocal course, put the rudder amidships so
that vessel will turn onto the reciprocal course.
If dealing
with a man overboard, always bring the vessel upwind of the person. Stop the
vessel in the water with the person well forward of the propellers.
NOTE: All of
the above turns to rescue a person fallen overboard, the point to keep in mind
is that the turns of every ship differs from the theory. Together with the
current and wind the ship may not be actually over the position as required. As
such a good look out – enough commonsense as to the drift and that a small head
in a vast ocean with waves is very difficult to see. Even with the ship having
retraced the path it may not always be possible to see a small head in the
waters. The MOB marker may drift not always at the same rate as that of the
person. SO good look out is very essential and good common seamanship.
Sequence of
actions to take when a person is seen to fall overboard
Throw a Life Buoy with a self-igniting light towards
the person in the water.
Send a lookout aft.
Rush to the manual call button and ring the alarm
bell.
If a telephone or hand held radio is accessible then
inform the Bridge watch-keeping officer
If above not available then go up on the bridge and
inform the watch-keeping officer. Information should be as to which side the
person fell and his identity.
Actions to take when a man-overboard report is received on the bridge
Assume that you are the watch keeper:
Put the helm on the same side to the person in the
water
Throw down the Man overboard marker
Post a look out astern with binoculars
Note down the position of the ship by all possible
means
Ring standby to the engine
Inform the Master
Ring the alarm bell for Emergency
Inform on the PA system that this is not a drill and
that a person has fallen overboard.
Note down the wind direction and study the current
direction
Ask for the rescue boat to be prepared
Depending on the instructions as laid down by the
Master commence the Williamson turn
Once you see the MOB marker astern or if the original
wake is noticeable, bring the vessel back on course
Inform all ships in the vicinity of the incident and
send out a distress message
Once the vessel is on reciprocal course and the
engines are ready for manoeuvring
Slow down and if the marker is visible head for it.
When very close to the MOB, stop engines and lower the
RB.