144 seamanship secretsHow to Become Sound Signal Savvy
When vessels are within sight of one another, they use sound signals to tell
each other the action they are taking or intend to take. In low visibility, sound
signals indicate a particular activity or status, such as dredging, sailing, an-
chored, or aground. All sound signals use distinct blast intervals, either alone
or in combination. A short blast is about 1 second, and a prolonged blast lasts
about 4 to 6 seconds.
In general, vessels use short blasts to indicate maneuvering or danger. In
low visibility, vessels underway sound a prolonged blast alone or in combina-
tion with short blasts.
Below are the most common signals for maneuvering and a few low vis-
ibility signals. Refer to Rules 32 to 37 in the Rules of the Road for more extensive
coverage of sound and light signals.SIGNALING INTENT
ON INLAND WATERS
In inland waters, the signals you make
to other vessels let them know that
you intend to do something (except
backing). Th is signal of intent must be
answered by the other vessel, blast for
blast. If you sound one short blast and
the other boat agrees, they must give
you one short blast in return (see key
below). If the other vessel doesn’t agree,
they must sound the d-o-u-b-t signal of
fi ve or more short blasts. Th en you may
begin the sequence of “ask?-answer” to
request to pass the vessel’s other side.
In any event, you don’t execute the
maneuver until you receive the same
signal in return. Here are the signals
that apply when two vessels meet or
cross on inland waters:
One short blast: I intend to leave you
on my port side
Two short blasts: I intend to leave
you on my starboard sideMemory Keys for Passing
Sound Signals
These memory keys should help you
remember what sound signal to use,
whether you signal intent (Inland
Waters) or take action (International
Waters). First, think of how you want
to keep the other vessel relative to
your own vessel. In other words, do
you want the other vessel off your
port side or your starboard side?
port has one syllable = one short
blast (to keep the other vessel off
your port side)
star-board has two syllables = two
short blasts (to keep the other
vessel off your starboard side)
I’m-going-astern is three words
= three short blasts (engines
operating in reverse for astern
propulsion)
d-o-u-b-t has five letters = five
or more short blasts (uncertain
situation or danger; see text)