With VHF radios as common as they are, you don’t hear sound signals on boats very much anymore. When you do hear one, it always seems to come as a shock, and sadly, it’s far to easy to have no clue as to what the boat issuing the signal is trying to say. For example, you are sailing along the San Francisco city front, approaching the Bay Bridge, and you hear a vessel sound a single prolonged blast (four to six seconds) followed by three short blasts (one second) what is going on? Easy … the single prolonged blast in this case means “I’m leaving the dock.” Three short blasts means using astern propulsion. In other words, the boat, most likely a ferry, is backing away from the dock. Where would you be if you hear a prolonged blast followed by a single short blast? Probably in the vicinity of a draw bridge (yes, there are still a few on the bay … next to ATT Park is an example). One prolonged followed by one short is the official request to open the bridge.
Here are a few more examples taken from the Inland Waters sections of the Navigation Rules. Yes, I know that in international waters the meaning might be a bit different, however, we are generally in the bay which is considered inland waters, so lets go with those signals for now.
- A single short blast means “I plan to leave you on my port side” (only applies when both vessels are power-driven). This signal should be responded to with the same signal if in agreement or five short blasts if not in agreement.
- Two short blasts means “I plan to leave you on my starboard side” (only applies when both vessels are power-driven). This signal should be responded to with the same signal if in agreement or five short blasts if not in agreement.
- Three short blasts means “I am operating astern propulsion.” This doesn’t necessarily mean backing up, it could mean using reverse to bring the vessel to a stop.
- Five or more short (or rapid) blasts indicates disagreement or danger. It means “I don’t understand your intentions or actions!”
- Once in awhile you might hear a single blast that never seems to end. It’s not a recognized sound signal, however the meaning pretty much comes through. Please don’t use it, but if you hear it, it means “If you don’t get out of the way you are going to get run down by a very big boat!”
- In good visibility, a single prolonged blast means either … leaving the dock, or rounding a bend in a channel or fairway where visibility is obscured.
- In limited visibility, a single prolonged blast repeated at intervals of no more than two minutes is the signal made by a power-driven vessel making way. A sailing vessel, a vessel restricted in her ability to maneuver, a fishing vessel, a vessel not under command, or a vessel towing (or pushing) will sound the same signal, followed by two short blasts, at the same interval.
- The same signal might have a different meaning when used in different context. Remember that prolonged blast followed by three short blasts. In restricted visibility it’s the signal made by a vessel being towed, and should be made soon after the towing vessel signals with a prolonged and two shorts.
While on the topic of sound signals, here is another “pet peeve.” You know the pump up sound signals on all of Tradewinds boats? They are totally useless unless the air bottle (signal) and the pump are together … at all times!!!
One last thing. VHF radios have pretty much replaced the use of sound signals in most circumstances. On the bay, channel 13 is reserved for radio traffic from one ship’s bridge to another. It doesn’t happen often however, occasionally I will hail large vessel traffic in a narrow channel to let them know my intentions before they get nervous. If you decide to do so, remember that you are on a “recorded line.” Follow radio etiquette and be professional.