Study sheet
Manoeuvring, warning and restricted-visibility signals — Rules 34–37, patterns rendered as blast notation.
You hear: one short blast. Vessels in sight of one another.
"I am altering my course to starboard" (verbatim, Rule 34(a)).
Examiner note: one PROLONGED blast is a different signal entirely — a bend (Rule 34(e)) or fog (Rule 35(a)). Context and blast length are everything.
You hear: two short blasts. Vessels in sight of one another.
"I am altering my course to port" (verbatim, Rule 34(a)).
Examiner note: in fog, two PROLONGED blasts mean underway but stopped (Rule 35(b)) — different length, different world.
You hear: three short blasts. Vessels in sight of one another.
"I am operating astern propulsion" (verbatim, Rule 34(a)).
Examiner note: it means her engines are going astern — not necessarily that she is moving astern yet.
In sight, you see one white flash of about a second. What is it?
The light-signal supplement to the whistle signals: one flash = altering to starboard, two = port, three = astern propulsion; flash and interval about one second, successive signals at least ten seconds apart; the light, if fitted, an all-round white visible 5 miles (Rule 34(b)).
You hear: two prolonged blasts, then one short. Narrow channel.
You hear: two prolonged blasts, then two short. Narrow channel.
"I intend to overtake you on your port side" (verbatim, Rule 34(c)(i)).
Examiner note: the vessel being overtaken signals agreement with prolonged–short–prolonged–short (Rule 34(c)(ii)).
You proposed to overtake; she replies: prolonged, short, prolonged, short.
Agreement — "one prolonged, one short, one prolonged and one short blast, in that order" (verbatim, Rule 34(c)(ii)). If in doubt she may instead sound the doubt signal.
You hear: at least five short and rapid blasts.
The doubt / wake-up signal — the vessel "fails to understand the intentions or actions of the other, or is in doubt whether sufficient action is being taken" (Rule 34(d)). May be supplemented by at least five short rapid flashes.
Examiner note: FOUR short blasts is a pilot vessel's identity signal (Rule 35(k)) — count carefully.
You are nearing a bend where vessels may be obscured. What do you sound — and what do you expect back?
One prolonged blast; answered with a prolonged blast by any approaching vessel within hearing (Rule 34(e)).
Examiner note: same blast as fog Rule 35(a) — visibility context distinguishes them.
Fog. You hear: one prolonged blast, repeating about every two minutes.
A power-driven vessel making way through the water (Rule 35(a)).
Examiner note: TWO prolonged means she is underway but STOPPED (Rule 35(b)).
Fog. You hear: two prolonged blasts about two seconds apart, every two minutes.
A power-driven vessel underway but stopped and making no way through the water (Rule 35(b)).
Examiner note: she is still UNDERWAY — not anchored (anchor is the bell, Rule 35(g)).
Fog. You hear: one prolonged followed by two short blasts.
The hampered-vessel signal, sounded instead of 35(a)/(b) by (verbatim list): A vessel not under command, a vessel restricted in her ability to manoeuvre, a vessel constrained by her draught, a sailing vessel, a vessel engaged in fishing and a vessel engaged in towing or pushing another vessel (Rule 35(c)).
Examiner note: one prolonged + THREE short is the manned TOWED vessel replying (Rule 35(e)).
Fog. A vessel at anchor sounds one prolonged and two short — not a bell. Is that right?
Yes — a vessel engaged in fishing at anchor, and a RAM vessel working at anchor, sound the Rule 35(c) signal INSTEAD of the anchor signals (Rule 35(d)).
Examiner note: a classic trap — the bell (35(g)) is for an ordinary vessel at anchor.
Fog. You hear: one prolonged followed by three short blasts.
A vessel towed — or the last vessel of the tow, if manned — sounded when practicable immediately after the towing vessel's signal (Rule 35(e)).
Examiner note: one prolonged + TWO short is the towing vessel herself (in the 35(c) group).
Fog. You hear the rapid ringing of a bell for about five seconds, every minute.
A vessel at anchor (Rule 35(g)). In a vessel of 100 m or more the bell is sounded in the forepart and immediately followed by the gong, rung rapidly for about 5 seconds, in the after part.
Examiner note: bell forward, gong aft — hearing both ends tells you her size and her heading.
Fog. From a vessel at anchor you also hear: short, prolonged, short on the whistle.
The optional anchor warning — "one short, one prolonged and one short blast" to warn an approaching vessel of her position and the possibility of collision (Rule 35(g)).
Fog. Three distinct bell strokes — rapid ringing — three distinct strokes again.
A vessel AGROUND: the anchor bell (and gong if 100 m or more) with "three separate and distinct strokes on the bell" immediately before and after the rapid ringing (Rule 35(h)). She may also sound an appropriate whistle signal.
Fog. You hear four short blasts.
A pilot vessel on pilotage duty may sound "an identity signal consisting of four short blasts" in addition to her 35(a)/(b)/(g) signals (Rule 35(k)).
Examiner note: at least FIVE short and rapid is the doubt signal (Rule 34(d)) — the pilot's four are deliberate, not rapid.
You need to attract another vessel’s attention. What may you use — and what must you avoid?
Any light or sound signal that cannot be mistaken for any signal authorised elsewhere in the Rules, or the beam of a searchlight directed at the danger, so as not to embarrass any vessel; the light must not be mistakable for an aid to navigation, and high-intensity intermittent or revolving lights such as strobes "shall be avoided" (Rule 36).
A vessel is in distress and requires assistance. Where do her signals come from?
Card backs quote the Rules — public sector information reproduced under the Open Government Licence v3.0 (source: MSN 1781 — see the Rules reference).
Independent preparatory study aligned to the MCA OOW (Yachts <3000 GT) oral examination syllabus. Not an MCA-approved course and confers no credit toward a Certificate of Competency.