How should I use VHF radio to help avoid collisions while boating?
I sail a 10-metre yacht and sometimes find it difficult to judge whether ships crossing our route have seen us. We have a DSC VHF with an AIS receiver: when should I call another vessel, which channel should I use, and what should I say?
Answer
Use VHF to contact an identified vessel early and clarify its intentions if a close encounter is developing. Keep a proper lookout and follow the collision regulations throughout: radio contact supports your assessment and must never delay avoiding action.
Assess the collision risk first
Establish which vessel concerns you, whether there is a risk of collision and how much time you have. A vessel approaching on roughly the same compass bearing is a classic warning. A changing bearing does not guarantee a safe passing distance, especially with large ships.
If crew are available, keep watching the traffic while someone handles the radio. If you are alone and the situation is already close, concentrate on controlling the boat and taking the action required by the collision regulations.
- Check that the VHF is powered, the volume is audible and the squelch is set just high enough to suppress background hiss.
- Keep a listening watch on Channel 16, alongside any locally required port or vessel traffic service channel.
- Check that your DSC radio has your correct MMSI programmed and a valid, current GPS position.
Being under sail does not always give you priority. Narrow channels, traffic separation schemes and the other vessel's operating status can change your obligations.
Call early and identify clearly
Call while there is ample room to assess the reply and manoeuvre. Use the ship's name from AIS where available, but check its position and direction against the vessel you can see. Contacting the wrong ship can give you dangerous reassurance.
For an initial voice call, use Channel 16 unless a published local procedure specifies another channel. Channel 16 carries distress, urgency, safety and calling traffic, so move a longer exchange to an appropriate working channel. Channel 13 is used for navigational safety communications in many areas; follow local arrangements.
Open with: "Motor vessel North Star, North Star, this is sailing yacht Willow, Willow. I am approximately one mile ahead of you, on your starboard bow, heading west at five knots. Do you have me in sight? Over."
Then state your concern and ask a specific question: "Your bearing appears steady and we are closing. What are your intentions? Over." Give your position, course and speed if identification remains uncertain. Avoid vague descriptions such as "the yacht near you".