VHF Radio Etiquette in Thai Waters: Channel 16, Protocol, and Weather

A VHF marine radio is the most critical safety device on any Thai fishing vessel operating beyond swimming distance from shore. It is also, for many visiting anglers, one of the least understood pieces of equipment they carry. The principles are not complicated — there are a handful of channels, a clear hierarchy of usage, and internationally standardised call procedures — but the consequences of using the radio incorrectly or not at all when conditions deteriorate can be severe in the isolated waters of the Andaman Sea and the Gulf of Thailand's offshore reaches.

The Legal Framework

VHF radio use in Thai waters is governed by Thai maritime law (Vessel Act B.E. 2481 and subsequent amendments), the Radio Communication Act B.E. 2498, and international obligations under the SOLAS Convention, to which Thailand is a signatory. Any vessel fitted with a marine VHF transceiver is legally required to maintain a continuous watch on Channel 16 whenever the radio is operational and the vessel is underway or at anchor in navigable waters.

There is no formal licensing requirement for operators of recreational fishing vessels using VHF radio in Thai waters, though the Thai Marine Department recommends operators hold at least a basic radio operator certificate. For visiting foreign nationals operating their own vessels, the international Short Range Certificate (SRC) is the appropriate qualification and is recognised in Thai waters.

The practical takeaway: keep Channel 16 monitored at all times when at sea. This is not merely advisable — it is a legal obligation and a safety necessity.

Channel Allocation in Thai Waters

Channel 16: The International Distress and Calling Channel

Channel 16 is the universal hailing and distress channel for all marine VHF operations worldwide. It operates at 156.800 MHz and must be monitored continuously. Its functions in Thai waters:

• Distress calls (MAYDAY) for life-threatening emergencies
• Urgency calls (PAN-PAN) for serious but non-life-threatening situations
• Safety calls (SECURITE) for navigational warnings
• Initial calling channel — vessels call each other on Channel 16 and then switch to a working channel once contact is established

Never use Channel 16 for routine boat-to-boat communication beyond the initial call. Occupying the channel with non-emergency traffic is a legal violation and prevents distress signals from being heard.

Working Channels in Thai Waters

After establishing contact on Channel 16, vessels switch to a designated working channel:

• Channel 6: Inter-ship communication for safety and coordination. Also used by some Thai charter operators as a coordination channel.
• Channel 9: A secondary inter-ship channel used in some areas as a congestion alternative to Channel 16 for routine traffic.
• Channel 25 and 26: Thai Meteorological Department weather broadcasts for Andaman (25) and Gulf (26) marine areas.
• Channel 72: Common inter-ship working channel for recreational vessels in international waters; used by some Phuket-based charter operations.
• Channel 77: Another inter-ship working channel used by recreational and fishing vessels in some areas of the Andaman.

Thai Navy and Marine Police vessels monitor Channel 16 and may operate on additional designated channels that are not publicly specified. Do not attempt to contact naval vessels except in genuine emergencies.

Calling Procedures: English and Thai

English Protocol (Standard International)

The English calling protocol is fully standard internationally and is recognised throughout Thai waters by all Thai authorities:

1. Call on Channel 16: "[Vessel name], [Vessel name], this is [your vessel name], [your vessel name], over."
2. Receiving vessel acknowledges: "[Your vessel name], this is [receiving vessel name], Channel [working channel], over."
3. Both vessels switch to the agreed working channel and complete communication.
4. End each communication with "over" (expecting a response) or "out" (ending the conversation). Never use "over and out" — these terms are mutually exclusive.

Speak clearly and at moderate pace. Spell any ambiguous words using the NATO phonetic alphabet (Alpha, Bravo, Charlie…). Phuket, Krabi, and Samui have significant English-speaking maritime communities and Charter operators respond to correct English protocol without difficulty.

Thai-Language Protocol

Thai working-channel communication between local fishing boats uses a less formal structure than the international protocol. Common Thai phrases in fishing VHF communication:

• "Phut yu?" (พูดอยู่?) — "Are you there?" (informal calling phrase)
• "Rao yu thi..." (เราอยู่ที่...) — "We are at..." (followed by location)
• "Pla dee mai?" (ปลาดีไหม?) — "How is the fishing?"
• "Fah mai dee" (ฟ้าไม่ดี) — "Weather is bad"
• "Kho chuay" (ขอช่วย) — "Request assistance"

Thai distress protocol follows the international MAYDAY format with Thai-language content substituted. The word "MAYDAY" is used unchanged regardless of language, as it is the internationally recognised distress signal. Thai-speaking anglers should know how to initiate a distress call in English even at a basic level, as the responding authority may not have Thai-language capability on Channel 16.

Making a Distress Call

If the vessel is in distress (sinking, fire, medical emergency requiring external assistance, missing crew):

Full MAYDAY call: "MAYDAY MAYDAY MAYDAY This is [vessel name] [vessel name] [vessel name] MAYDAY [vessel name] My position is [GPS coordinates — latitude and longitude, or bearing and distance from a known landmark] I am [nature of distress: sinking / on fire / medical emergency / we have lost power] We have [number of persons on board] [Any other relevant information: vessel type, colour, taking on water] I require immediate assistance Over"

Repeat the call if no acknowledgement is received within one minute. In the Andaman Sea beyond 30 km from the coast, signal propagation may require multiple attempts to reach a vessel or station with line-of-sight coverage. Digital Selective Calling (DSC) — the distress button function on VHF sets equipped with DSC — transmits an automated MAYDAY with the vessel's GPS position without requiring a voice call, provided the radio is connected to a GPS source.

PAN-PAN call for serious but non-life-threatening situations (engine failure with vessel drift, minor medical issue, vessel aground but stable): "PAN-PAN PAN-PAN PAN-PAN All stations or [specific station name] This is [vessel name] [Nature of the urgency and position] Over"

Weather Broadcasts

Thai Meteorological Department (TMD) Marine Forecasts

The TMD issues marine weather forecasts for the Andaman Sea and Gulf of Thailand regions twice daily. These broadcasts are announced on Channel 16 and then broadcast on designated working channels. The content includes:

• Wind direction and speed (in knots and Beaufort scale)
• Wave height and period
• Visibility
• Storm or gale warnings if applicable
• 24 to 48-hour forecast outlook

Broadcast channels and times vary by season and by region. During the southwest monsoon (May to October), when the Andaman Sea can experience Force 6 to 8 conditions, the TMD increases broadcast frequency and includes specific storm track information.

Regional Variation: Andaman versus Gulf

The Andaman Sea and Gulf of Thailand are meteorologically distinct water bodies and their weather forecasts are issued separately:

Andaman Sea: Receives full force of the southwest monsoon (May to October) and is generally calmer from November to April. The southwest monsoon brings strong southwesterly winds (20 to 35 knots), significant swell (2 to 4 metres), and rapidly deteriorating conditions when frontal systems pass. The Andaman is operationally closed to most recreational and charter fishing from June to September.

Gulf of Thailand: Has a more moderate monsoon pattern. The northeast monsoon (November to February) brings occasional strong winds on the northern Gulf but the southern Gulf around Koh Samui and the Ang Thong group remains more sheltered. The Gulf is generally fishable year-round at some location, even during the monsoon. The weather forecast for the upper Gulf (Bangkok Bight northward) and lower Gulf (below the Kra Isthmus) are effectively separate micro-climates.

Pattani Variance

The Pattani coast and the southern Gulf of Thailand near Narathiwat and Yala provinces experiences its own secondary weather pattern that differs from both the main Andaman and Gulf forecasts. The area is influenced by the South China Sea monsoon system, producing heavy rainfall and rough sea states in November to December that are not reflected in the general Gulf forecast. Anglers fishing from southern Gulf ports (Pattani, Narathiwat) should seek local weather information from harbour masters rather than relying on the general TMD Gulf forecast.

Equipment Recommendations

A fixed-mount VHF radio is required for vessels making offshore passages. A handheld VHF is adequate as a backup but insufficient as a primary radio — its antenna height above sea level is limited by where the user is holding it, significantly reducing range compared to a masthead or upper-structure antenna.

For fishing vessels in Thai waters, a DSC-capable VHF with GPS integration (so that the distress button transmits vessel position automatically) is the recommended minimum specification. These units cost 5,000 to 15,000 baht from Thai marine equipment suppliers and are a legitimate safety investment for any vessel that operates offshore.

Handheld waterproof VHF units (IP67 rated) serve well as backup units and are appropriate for kayak anglers and small boat operators in inshore conditions. Keep the handheld charged and accessible — not in the bottom of a tackle bag — at all times when afloat.

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