Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, and space navigation.
It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks. All navigational techniques involve locating the navigator’s position compared to known locations or patterns.
Navigation, in a broader sense, can refer to any skill or study that involves the determination of position and direction. In this sense, navigation includes orienteering and pedestrian navigation.
In the European medieval period, navigation was considered part of the set of seven mechanical arts, none of which were used for long voyages across open ocean. Polynesian navigation is probably the earliest form of open-ocean navigation, it was based on memory and observation recorded on scientific instruments like the Marshall Islands Stick Charts of Ocean Swells. Early Pacific Polynesians used the motion of stars, weather, the position of certain wildlife species, or the size of waves to find the path from one island to another.
Just as lights play a significant role in understanding what other boats are doing, so do sounds. Understanding what you hear is another step towards being a “complete mariner”. Virtually every boat is required to have some sound producing device. There is a great deal of latitude in what type of sound making device you choose, but loud is good!
A change in direction can be communicated by sound signals. One blast says “I intend to pass you on my starboard side.” Three short blasts tell other boaters, “I am operating astern.” For some vessels, this tells other boaters, “I am backing up.”
Equipment for Sound Signals is based on the length of your boat as follows.
- Boats less than 39.4 feet in length – must carry an efficient sound producing device. In general, this may be a bell, whistle, or air horn. Though guns–even pots and pans–can make a suitable sound signal useful in getting attention in an emergency, you should always carry the appropriate equipment.
- Boats at least 39.4 feet to less than 65.6 feet in length – Must carry a whistle and a bell. The whistle must be audible for 1/2 nautical mile. The mouth of the bell must be at least 7.87 inches in diameter.
When and How to Sound Off
Sound signals are to be used only when vessels are in sight of each other and are meeting or crossing at a distance within half a mile of each other. These signals must never be used in fog or other conditions of reduced visibility, where the vessels are not visible to each other by eye. Only the fog signals listed under the Inland Rules, Rule 35 may be sounded at such time.
- Short Blast – Lasts about one second.
- Prolonged Blast – Lasts from four to six seconds.
There are different blasts combinations for various movements on the water that may use both short and prolonged blasts. When power-driven vessels are in sight of one another and meeting or crossing at a distance within half a mile of each other, each vessel underway, when maneuvering as authorized or required by the Inland rules must use the following sound signals.
- One Short Blast – This means “I intend to leave you on MY port side”“. When you pass near another boat, you will manuever by leaving them on your left side as you pass. If you are behind another boat, going the same direction and about to overtake it, one short blast means: “I intend to pass you on YOUR starboard side, MY port side”.
- One Prolonged Blast – This means you are leaving a dock or departing your slip. It signals to others a change in status and that you are getting underway. A prolonged blast is also sounded when a vessel is approaching a bend in a river where vessels coming from another direction cannot be seen. It is sometimes referred to as the “blind bend signal”.
- Two Short Blasts – This means “I intend to leave you on MY starboard side”. When you pass near another boat, you will manuever by leaving them on your right side as you pass. If you are behind another boat, going the same direction and about to overtake it, two short blasts means: “I intend to pass you on YOUR port side, MY starboard side.”
- Three Short Blasts – This means you are operating in astern propulsion, for example backing away from a dock
- One Prolonged Blast + Three Short Blasts – This is technically two different signals in succession. One prolonged blast indicates you are getting under way, and three short blasts indicate you are backing up. This is what is sounded when you are departing a dock in reverse.
- Five Short Blasts – This is the DANGER signal. Remember, that when you approach another vessel and hear either one or two short blasts, and you both understand their signal and can safely let them do it, then you are required to respond with the same signal in response. However, if you don’t understand their intentions, or feel that their proposed maneuver is dangerous to either vessel, then you are required to sound the DANGER signal.
Proper Sound Signals
Passing Port to Port
When you meet an oncoming vessel, and wish to pass port to port, you are required to sound one short blast with your horn. If the other boat is in agreement, they should respond with a similar blast.
Passing Starboard to Starboard
If you approach another vessel head on, and wish to pass it on its starboard side, you are required to sound two short blasts with your horn. If the other vessel is in agreement, they should sound the same signal in response.
Overtaking on Portside
When you are planning on passing another vessel from behind, there are several things you must do. Any vessel that is overtaking another must keep out of the way of the vessel being overtaken. This means that you can’t expect them to move, slow down, or change their course. If you plan on passing them on THEIR starboard side, you must sound one short blast. If they understand your signal and agree, they will sound one short blast in response. The vessel being overtaken has a responsibility to maintain course and speed in order to minimize the potential for collision.
Overtaking on Starboard
When you are planning on passing another vessel from behind, there are several things you must do. Any vessel that is overtaking another must keep out of the way of the vessel being overtaken. This means that you can’t expect them to move, slow down, or change their course. If you plan on passing them on THEIR PORT side, you must sound two short blasts. If they understand your signal and agree, they will sound two short blasts in response. The vessel being overtaken has a responsibility to maintain course and speed in order to minimize the potential for collision.
Similarly, you may ask, what does 3 blasts of a ship horn mean?
Three Short Blasts – This means you are operating in astern propulsion, for example backing away from a dock. One Prolonged Blast + Three Short Blasts – This is technically two different signals in succession. One prolonged blast indicates you are getting under way, and three short blasts indicate you are backing up.
Likewise, what does 5 short horn blasts mean? Five or more short and rapid blasts – Danger or doubt signal (I don’t understand your intent). Vessels indicate their intention to maneuver by using sound signals. If you do not agree with or understand clearly what the other vessel’s intentions are, you should sound the danger or doubt signal (5 short, rapid blasts).
Additionally, what do ship horn blasts mean?
One short blast = Passing on ship’s port side. Two short blasts = Passing on ship’s starboard side. Three short blasts = Operating in reverse. Five short blasts = Danger signal.
What does long blast and two short blasts mean?
Restricted Visibility One prolonged blast at intervals of not more than two minutes is the signal used by power-driven vessels when underway. One prolonged blast plus two short blasts at intervals of not more than two minutes is the signal used by sailing vessels.
What does it mean when a ship blows its horn 3 times?
Three Short Blasts This signal indicates that you are backing up.
What does 3 long and 2 short horns mean?
3 long and 2 short: Master salute. 5 or more short quick blasts: Danger.
What does 4 blasts of a ship horn mean?
prepares to depart the dock the skipper gives four blasts on the horn to alert local boaters they are getting underway. Whether this is an official rule, I do not know, but perhaps so. Terry.
What does 5 short blasts mean?
Warning. One prolonged blast is a warning signal (for example, used when coming around a blind bend or leaving a dock). Five (or more) short, rapid blasts signal danger or signal that you do not understand or that you disagree with the other boater’s intentions.
What does it mean when a cruise ship blows its horn?
The ship’s horns harken back to a day before radios and loudspeakers. They serve as communication with other boats in the area, telling them what the cruise ship is planning to do. Without the horn signals, the risk of a collision would be much greater.
What is the signal for abandon ship?
4) Abandon Ship Alarm: More than six short blasts and one prolonged blast on the ship’s whistle and the same signal on the general alarm bell is used as an abandon ship alarm or sound signal onboard ship.
What action should you take if you are approaching another boat at night and see a white light?
If only a white light is visible, you may be approaching another craft from behind. You are the give-way-craft and must take early and substantial action to steer well clear by altering your course and passing at a safe distance on the starboard (right) or port (left) side.
What is a ships master salute?
A “Master Salute” is a formal salute, sounded by a watercraft during special occasions. Those within range of the Veterans Museum will hear three long whistle blasts, followed by two short blasts, throughout the downtown area, according to the press release.
How many blasts does an air horn have?
115 dB sound. Loud enough to be heard up to 1 mile. USCG Certified. Up to 70 blasts (1 second blast)
How far can you hear a cruise ship horn?
The Requirements. According to the latest edition of the Navigation Rules (COMDTINST M16672. 2D), all vessels greater than 65.6 feet are required to have a sound-producing device. Most recreational boats are required to have a whistle or horn capable of being heard one-half mile away (Rule 33.
Thanks for joining this post “what do three short blasts of a horn indicate”.