NZ MVOC (VHF Radio) cheat sheet

Channel 16 (156.800 MHz) is the international distress, safety and calling channel; use it to establish contact, then move to a working channel.

Standard call format: say the called station's name up to three times, "this is" plus your station name and callsign, then "over".

Use "over" to end a transmission and invite a reply; use "out" to end a contact with no reply expected; never say "over and out".

Spell difficult words with the ITU phonetic alphabet (Alfa, Bravo, Charlie ... Zulu) and give numbers digit by digit.

Recreational vessels in NZ generally identify by vessel name; a registered Maritime NZ callsign or MMSI may be used where fitted.

Listen before transmitting; if Channel 16 is busy, wait for a clear slot rather than talking over another station.

Keep transmissions short and to the point; long calls on 16 block distress traffic.

Channel 16 may be monitored by a coast station or by other vessels; it is not a private or chat channel.

MAYDAY = distress (grave and imminent danger, immediate assistance required); sent on Channel 16, repeated until answered.

PAN PAN = urgency (important safety message concerning a vessel or person, but no immediate grave danger).

SECURITE = safety (navigational or weather warning); pronounced "say-cure-e-tay".

Distress call sequence: MAYDAY x3, "this is", vessel name and callsign x3, MAYDAY, vessel name/callsign, position, nature of distress, assistance required, persons on board, "over".

Distress acknowledgement: "MAYDAY", called vessel's name x3, "this is", your vessel name/callsign, "received MAYDAY", then relay the distress details.

If you hear a distress call and no one answers, acknowledge it and relay to a coast station or Rescue Coordination Centre.

Impose radio silence with "SILENCE MAYDAY" (or "SILENCE DISTRESS"); lift it with "SILENCE FINISHED".

A MAYDAY RELAY is used when relaying a distress from another station or when a coast station relays to a rescue asset.

Marine VHF use in NZ is governed by the Radiocommunications Act 1989 and Maritime NZ rules; Channel 16 distress use is internationally protected.

Only transmit on channels you are authorised to use; unauthorised transmissions, false distress calls and interference are offences.

Channel 16 is for distress, urgency, safety and calling only; do not use it for routine or social traffic.

Do not transmit on Channel 70 (DSC) by voice; it is reserved for Digital Selective Calling only.

AIS channels 87B (161.975 MHz) and 88B (162.025 MHz) are reserved for AIS; do not use them for voice.

Maintain a listening watch on Channel 16 when the radio is on and the vessel is underway, unless a coast station directs otherwise.

Do not transmit without a valid authority: ship station licence (where required) and operator certificate.

Radio silence must be obeyed: only stations involved in the distress may transmit while silence is imposed.

In New Zealand, the Maritime NZ Marine VHF Radio Operator Certificate (MVOC) is the standard operator qualification for recreational and small commercial vessels.

The MVOC is issued after completing an approved course and passing the assessment; it covers VHF operation, distress/urgency/safety procedures and regulations.

A ship station licence is generally required to operate a marine VHF transmitter; check current Maritime NZ / RSM requirements.

The operator certificate is personal to the holder and should be carried or available on board.

MMSI (Maritime Mobile Service Identity) is a nine-digit number issued for DSC-equipped vessels; it must be programmed into the radio.

The MMSI is used for DSC distress alerts, individual calls and AIS; it is not the same as a callsign.

Certificate holders must know the limits of their authority: distress, urgency and safety traffic takes priority over all other use.

Renewal and refresher requirements should be checked with Maritime NZ; keep certification current.

Marine VHF band is 156–174 MHz; Channel 16 = 156.800 MHz, Channel 6 = 156.300 MHz (intership safety), Channel 13 = 156.650 MHz (bridge-to-bridge).

Channel 70 (156.525 MHz) is DSC only; no voice.

Channels 87B and 88B are AIS; do not use for voice.

VHF is essentially line-of-sight; range is typically 15–30 nautical miles depending on antenna height and conditions, much less at low antenna height.

Output power is typically switchable between 1 W (low) and 25 W (high); use low power for short-range and high power when needed.

DSC (Digital Selective Calling) sends a digital alert with MMSI, position and nature of distress; it is not a voice call.

A VHF radio should be connected to a GPS so DSC distress alerts include position; check the connection.

Batteries and antennas are the most common failure points; carry a spare battery or handheld as backup.

Channel 16 must be monitored whenever the radio is operating, unless the coast station directs otherwise.

If no answer on VHF, try other means: mobile phone, EPIRB, flares, or another vessel.

EPIRB (406 MHz) alerts rescue authorities via satellite; it is not a VHF device but complements VHF distress.

DSC distress alert on Channel 70 should be followed by a voice MAYDAY on Channel 16.

If time is short, send a MAYDAY on Channel 16 without DSC; do not delay distress for procedure.

Give position in latitude/longitude if known, otherwise bearing and distance from a known landmark.

State nature of distress (sinking, fire, medical, grounding), number of persons on board and assistance required.

Keep the radio on and listen after sending a distress; rescue coordination may call back.

If you hear a distress and can assist, acknowledge and proceed; if not, stand by and relay.

Medical emergencies may be handled as PAN PAN urgency if not immediately life-threatening, or MAYDAY if grave and imminent.

Rescue Coordination Centre New Zealand (RCCNZ) coordinates maritime search and rescue in the NZ search and rescue region.

RCCNZ can be contacted via coast stations, directly by satellite/phone, or through the distress system; VHF Channel 16 reaches coast stations in many areas.

Coast stations (e.g. Maritime Radio) maintain a listening watch on Channel 16 and can relay to RCCNZ.

In a MAYDAY, give position, nature of distress, persons on board and assistance required; RCCNZ uses this to task rescue assets.

Rescue assets include Coastguard, RNZAF, Navy, police and commercial vessels; RCCNZ coordinates them.

Keep a listening watch and follow RCCNZ or coast station instructions; do not abandon the vessel until advised or forced.

If you are not the casualty, do not transmit over the distress; stand by and offer assistance if able.

After rescue, advise RCCNZ or coast station that you are safe so the search can be stood down.

Use the correct channel for the purpose: 16 calling/distress, 6 intership safety, 13 bridge-to-bridge, 70 DSC, 87B/88B AIS.

When calling a coast station, give your vessel name and callsign and state the purpose of the call.

When calling another vessel, use its name and your name; if no answer after a few calls, try another channel or method.

End a call with "out"; if you need a reply, use "over".

Do not use profanity, unnecessary chatter or commercial traffic on distress/safety channels.

Keep a written log of distress, urgency and safety traffic if practical.

Priority order: distress (MAYDAY) > urgency (PAN PAN) > safety (SECURITE) > routine.

A MAYDAY must not be sent unless the vessel or person is in grave and imminent danger and immediate assistance is required.

A false MAYDAY is an offence and can divert rescue assets from real emergencies.

If a MAYDAY is sent in error, cancel it immediately with a MAYDAY CANCEL message on Channel 16.

PAN PAN is used for urgent messages such as a vessel not in immediate danger but needing assistance, or a medical advisory.

SECURITE is used for navigational warnings, weather warnings and other safety information.

A distress relay should be prefixed "MAYDAY RELAY" and include the original distress details.

Stations must not cause harmful interference and must accept interference from authorised services.

Transmissions must be limited to the minimum power and duration necessary.

The radio must not be used for private or commercial messages except as permitted.

Distress frequencies must be kept clear; only distress traffic may use them during silence.

Operators are responsible for the correct use of the radio and for the conduct of communications.

Records of radio licences and certificates should be available for inspection.

The MVOC is not the same as a commercial radio operator certificate; check which certificate your vessel requires.

DSC operation requires knowledge of MMSI programming and menu use; the MVOC covers this.

Operators should know how to test the radio (e.g. power-on test, DSC test call) without causing interference.

Keep the certificate and any licence documents on board or readily available.

Training providers approved by Maritime NZ deliver MVOC courses; the certificate is issued after assessment.

Operators must understand the limits of VHF and when to use other distress means.

Antenna height is the biggest factor in VHF range; masthead antennas give the best line-of-sight range.

VHF propagation is affected by weather and terrain; range can be reduced by hills, buildings and sea state.

Handheld VHF radios typically have lower power (1–5 W) and shorter range than fixed sets.

Channel 16 is 156.800 MHz; Channel 6 is 156.300 MHz; Channel 13 is 156.650 MHz; Channel 70 is 156.525 MHz.

DSC radios must have a correctly programmed MMSI; without it, DSC functions will not work properly.

A VHF radio should be tested regularly; a radio check can be requested from a coast station on a working channel.

If the vessel is sinking, send MAYDAY before abandoning; give position and persons on board.

If there is a fire, give nature of distress and whether you are abandoning.

For medical emergencies, state the nature of the illness/injury and whether medical advice is needed.

If you have a DSC radio, press the distress button (covered) and then send a voice MAYDAY.

If you have an EPIRB, activate it if the vessel is in grave and imminent danger and you cannot communicate by radio.

Use flares only when you can see a potential rescuer; follow local rules.

Keep the radio dry and powered; a handheld in a waterproof bag is a useful backup.

RCCNZ operates 24/7 and can be reached via Maritime Radio or directly by phone/satellite.

Give your position in latitude/longitude or as a bearing and distance from a charted landmark.

State the number of persons on board and any injuries; this determines the rescue response.

Follow RCCNZ instructions; they may ask you to switch to a working channel.

If you are relaying a distress, use MAYDAY RELAY and pass the details to RCCNZ.

After the rescue, notify RCCNZ or the coast station that you are safe.