The sound signals used in the collision regulations are
vital yet can be complicated if you do not know Morse Code. Fortunately
it is quite easier to create mnemonics for them.
Note: the interpretation of the collision regulations below
is sometimes simplified for the purpose of remembering. Always check
a copy of the regulations for the full definition.
The first choice when meeting another vessel
head on would be to turn to starboard, so one short
blast means turning to starboard.
See Clockface below
The second choice when meeting another vessel
head on would be to turn to port, so two short
blasts means turning to port.
See Clockface below
The third choice when meeting another vessel
head on would be to go astern, so three short
blasts means going astern (strictly speaking, engines in reverse).
The engines are in threeverse!
You could also imagine a propellor (it obviously helps if you see
three blades when you think of a propellor).
If you didn't know what the other person was doing, you might
sound many blasts in panic, so five short blasts means "Make
your intentions clear". The word PANIC has five letters.
One way of remembering the first two signals is to think of a
clockface. If you imagine the overtaking vessel at the centre of
the clock and the ship being overtaken at the twelve o'clock position,
then passing to starboard would go through the 1 numeral so ONE
blast, while going to port would go through the 11 numeral so ONE
+ ONE blast.
Signal
Description
Mnemonic
Four blasts indicate a pilot vessel. A pilot guides a ship into a
harbour. Think of the four blasts as four raps on a door (rat-ta-ta-tat)
to indicate that you want to come into a house.
The single long dash is sounded when approaching a blind bend
in a channel. in the same way, a motorist approaching a blind corner
might sound a long blast on his horn.
The double long blast indicates an overtaking manoeurve. Think
of the two long blasts as two ships in line, one about to overtake
the other.
The overtaking ship sounds two long blasts to indicate overtaking,
then one short to show that it is moving to starboard (as in the
single short blast above.)
The overtaking ship sounds two long blasts to indicate overtaking,
then two short to show that it is moving to port (as in the double
short blasts above.)
This signal marks agreement from the overtaken ship. Think of
it as one ship asking OK and the other agreeing OK
OK? OK
Sound Signals Mnemonics in Restricted
Visibility
Restricted visibility signals start with a long blast.
Imagine it long so as to give you time to focus on where it is coming
from.
Signal
Description
Mnemonic
The most common ship at sea is a powered vessel so it has the
simplest signal – a single long blast. (This signal is
for underway, not making way).
The long and two short blasts is given by vessels which cannot
manoeuvre as easily (not under command, unable to manoeuvre,
restricted by draught, fishing, towing, sailing). Think of it
as the ship warning "oh-oh".
"OH" "OH"
A vessel under tow, if manned, gives a long blast and three
short blasts. Imagine it as the tug dragging three barges behind
(TUG and TOW both have three letters).
At Anchor
At anchor, a vessel sounds a bell. Like a buoy, the
vessel will stay in one place. A buoy's sound signal is often a bell
as well.
A
vessel at anchor sounds a bell for five seconds every minute. You
could think of the bows of the vessel as a V (seen from above) which
is the Roman letter for 5. A traditional anchor (left) also has a
clear V shape.
Aground
A (large) vessel aground shows three balls
in line during the day. As a sound signal, it sounds three strokes
of the bell before and after the normal five seconds ringing for
anchoring (see above).