Rule 37: distress signals.

What does COLREGs Rule 37 say?

It is a single sentence. When a vessel is in distress and needs help, the signals she must use or display are the ones Annex IV describes. Rule 37 lists none itself; the signals are all in the annex.

What is in Annex IV?

Three sections. Section 1 lists the signals that indicate 'distress and need of assistance' — fifteen of them, lettered (a) to (o). Section 2 prohibits their misuse. Section 3 draws attention to further guidance and to two more signals used in search and rescue.

Do you have to use more than one distress signal?

No. Annex IV section 1 says the signals may be used or exhibited 'either together or separately', so any one of them indicates distress and need of assistance. In practice, a vessel in distress uses whatever is most likely to be seen, heard or received by someone who can help — and more than one signal if she can.

Which distress signals are sound, fire, flares or smoke?

(a) Gunfire or other explosive signals, at intervals of about a minute.

(b) Any fog-signalling apparatus, sounded continuously.

(c) Red stars thrown by rockets or shells, fired one at a time at short intervals.

(h) Flames on the vessel — the annex gives a burning tar barrel or oil barrel as examples.

(i) A red light from a rocket parachute flare or a hand-flare.

(j) Orange-coloured smoke from a smoke signal.

Which are code, flag, shape and arm signals?

(d) SOS — the Morse group …---… — made by any signalling method.

(f) The International Code Signal of distress, N.C. As a flag signal, it is the hoist N over C.

(g) A ball, or something that looks like one, shown above or below a square flag.

(k) Arms outstretched to each side, raised and lowered slowly and repeatedly.

Which are radio and electronic signals?

(e) The spoken word 'MAYDAY', sent by radiotelephony.

(l) A distress alert by digital selective calling (DSC) on VHF channel 70, or on MF/HF on 2 187.5 kHz, 4 207.5 kHz, 6 312 kHz, 8 414.5 kHz, 12 577 kHz or 16 804.5 kHz.

(m) A distress alert sent ship-to-shore through the ship's satellite ship earth station — Inmarsat, or another mobile satellite service provider.

(n) Signals from emergency position-indicating radio beacons (EPIRBs).

(o) Approved signals sent by radiocommunications systems — survival craft radar transponders among them.

How do you tell the arm signal from a wave?

By the movement Annex IV 1(k) describes: the arms are held outstretched to each side and raised and lowered slowly and repeatedly. In practice, a friendly wave of one hand is not that signal — but if you are in any doubt about what you are seeing, treat it as a possible distress signal and find out.

Can you use a distress signal when you are not in distress?

No. Annex IV section 2 prohibits using or exhibiting any of the section 1 signals except to indicate distress and need of assistance. It also prohibits using other signals which may be confused with any of them.

As we read it, that rules out firing a red flare for any other purpose — to attract attention, for instance, or to get rid of an out-of-date one — and sounding the fog signal continuously for any reason but distress.

What else does Annex IV section 3 mention?

It points the reader to the International Code of Signals and to Volume III of the IAMSAR Manual (the International Aeronautical and Maritime Search and Rescue Manual). It also mentions two signals: orange canvas marked with a black square and circle, or another suitable symbol, so that it can be identified 'from the air'; and a dye marker.

These are not among the fifteen signals in section 1; section 3 draws attention to them rather than listing them as distress signals.

How does Rule 37 differ from Rule 36?

Rule 36 lets any vessel signal to attract another vessel's attention, with light or sound signals that cannot be mistaken for any signal authorised elsewhere in the rules, or with a searchlight directed towards the danger. Rule 37 is for a vessel in distress that needs assistance. A vessel that only needs to be noticed uses Rule 36 — never a distress signal.

How might Rule 37 come up in an MCA oral?

It may come up as a list to give, or as a signal to recognise. Examples of the kind of question to be ready for:

“Name as many distress signals as you can.”

“At night you see red stars thrown up one at a time from a vessel on the horizon. What does that mean?”

“What is the distress signal made with a square flag and a ball?”

“A vessel nearby is sounding her fog signal continuously. What could that mean?”

“Can you fire a red hand-flare to attract another vessel's attention?”

“What does Annex IV say about orange canvas and dye markers?”

Where do candidates go wrong on Rule 37?

The common slips: naming a few flares and stopping; forgetting the radio and electronic signals — MAYDAY, DSC, the satellite alert, EPIRBs and survival craft radar transponders; describing the arm signal wrongly; counting the orange canvas and dye marker among the section 1 signals; and offering a distress signal as a way to attract attention.

In our view the list is easier to give in full if you learn it in groups — sound, fire and smoke; code, flags and arms; radio — rather than letter by letter.