What sound signal should motorized boat operators use when they are operating during reduced visibility?

In just minutes, fog, heavy rain, and in some cases even snow can reduce visibility on the water to just a few yards, leaving boaters confused as to their position, and what obstructions may be around them. At sunset recognizable shoreline features disappear, often replaced by unfamiliar and confusing lights that leave many boaters disoriented and unsure how to get safely home. At night, depth perception and color recognition are impaired. Other boats may be operating without required navigation lights, in violation of federal law requiring navigation lights from sunset to sunrise and during periods of restricted visibility. Without lights they can be very difficult to see in the water.

Operating a boat when visibility is restricted raises the risk of hitting fixed objects in the water and colliding with other boats. That’s why it’s prudent to lessen your risk by taking preventive action that includes slowing to a safe speed, energizing your navigation lights, and sounding the appropriate sound signals for your vessel type, as required by the Navigation Rules, available online through the Coast Guard Navigation Center at www.navcen.uscg.gov. It is also important to post responsible lookouts who will use all of their senses – sight, sound, even smell – to determine what lies ahead in time to avoid an accident. A lookout should scan 360 degrees, as accidents at night can occur when a vessel is overtaken from behind.

Illustrations and descriptions of the specific lighting requirements for every type of watercraft are provided in the Navigation Rules, which should be your primary source of information. Briefly speaking, however, these are the navigation lights required for recreational vessels:

• Sidelights: These red and green lights are visible to another vessel approaching from the side or head-on. The red light indicates a vessel's port (left) side; the green indicates a vessel's starboard (right) side. These lights are also referred to as combination lights when displayed on a vessels bow, or, in the case of sailboat, when on top of the mast.

• Stern Light: This white light can be seen from behind or nearly behind the vessel.

• Masthead Light: This white light shines forward and to both sides and is required on all power-driven vessels. Since a masthead light must be displayed by all vessels when under engine power, the absence of this light indicates a sailboat under sail.

• All-Round White Light: On power-driven vessels less than 39.4 feet in length, this light may be used to combine a masthead light and stern light into a single white light that can be seen by other vessels from any direction. This light also serves as an anchor light when sidelights are extinguished.

Remember that displaying the proper navigation lights at night and during periods of restricted visibility is only half of the issue. You also need to be able to identify and interpret the navigation lights you see on other boats in the vicinity. This can help you determine if you are in an overtaking, meeting or crossing situation.

After dark, the painted color patterns of Aids to Navigation – the buoys and beacons that mark safe water and hidden dangers and tell boaters their position in relation to land – are generally replaced by a configuration of lights. You will need to be able to identify these navigation aids to help determine your position and stay out of dangerous situations. To get an accurate position you will need to use a nautical chart. The chart will show you the position of the Aids to Navigation, their light characteristics and what landmarks you may be able to see and identify once the sun goes down.

In addition to navigation lights, the Navigation Rules require all vessels to carry sound-producing devices for use during meeting, crossing, and overtaking situations. Sound signals are also required during periods of reduced visibility to make other boaters in the area aware of your relative position and the status of your vessel; for example, a power driven vessel underway and making way is required to sound one prolonged blast at intervals not to exceed two minutes.

Is it easy to get lost or disoriented when visibility is limited? It is. Things look very different at night, which can be stressful for inexperienced boat operators. Expect the unexpected. Practice good risk assessment when deciding whether to boat in the dark. Make sure your required safety equipment is on board, including visual distress signals, and that everyone is wearing a life jacket. Take a boating course through your local Coast Guard Auxiliary, United States Power Squadrons® or State boating authority and educate yourself on best practices for boating at night. Your seamanship skills and good conduct on the water will help alleviate the stress and ensure that you, your passengers and your vessel return safely to your mooring.

Cruising in the Dark

Evening romantic? Early morning angler? Be sure to check the weather forecast before heading out, either from local media or your marine VHF-FM radio weather channel. Statewide weather forecasts and warnings are available from the National Oceanic and Atmospheric Administration (NOAA) at www.noaa.gov, which also lists local National Weather Service contacts. Besides checking for any incoming storms, consider the phases of the moon and the amount of cloud cover, both of which can affect your visibility in the dark. Practice risk assessment. Is it a high-traffic holiday weekend? Is there a full moon?

Have a clear idea of where you want to go and plot a course before leaving the dock. Study the route for water depth, landmarks, navigation aids and any hazards, then mark your progress on your chart as you go. Practicing these basic rules of navigation will lessen your risk of becoming disoriented, lost or running aground. Also make a habit of filing a float plan with a relative or friend who can then make the appropriate notifications if you fail to return as scheduled.

In addition to having current charts onboard, use your radar and GPS, if so equipped. But don’t rely on GPS alone. Operating in or near areas of restricted visibility raises the risk of an allision, which is when a moving vessel strikes a fixed object, or a collision when vessels underway strike each other. A GPS can’t tell you what obstructions are just under the surface of the water or between you and your destination.

Make sure that your navigation lights are “energized and burning brightly,” as specified by the Navigation Rules, prior to leaving the dock. Illustrations of appropriate lighting for your vessel can be found in A Boater’s Guide to Federal Requirements for Recreational Boats and Safety Tips, online at //www.uscgboating.org/regulations/federal_requirements_brochure.aspx. Make sure you have extra light bulbs and fuses aboard.

Other than your navigation lights, eliminate all white lights on board as they can affect your night vision and reduce your ability to see other vessels and objects in or on the water. Consider replacing them with red lights, which will not affect your night vision. Set your instrument panel dimmer switch to the lowest readable setting.

Do a marine VHF-FM radio check with a marina, another boat, or the towing companies to make sure it’s working properly and, as with every excursion, make sure you have a full fuel tank before heading out. You never want to run out of fuel, but especially not in the dark.

Finally, keep the distractions down. Turning down music and TVs and asking your passengers to keep conversation at a reduced level while underway in restricted visibility will improve your abilities as a lookout.

Boating in Fog

Fog can develop very quickly and brings an increased risk of collision. In fog, if other boats can’t see you they need to hear you. If you see fog moving in, do the following before your visibility becomes seriously reduced:

• Fix your position on a chart or mark it on an electronic plotter. • Reduce your speed to the point where you can stop your vessel in half the distance you can actually see. • Turn on your navigation lights. • Instruct any passengers to help you keep watch – by sight, sound, and smell – preferably in the bow. • Begin sounding one prolonged blast on your horn (4–6 seconds) every two minutes while underway and making way and two prolonged blasts every two minutes when underway and stopped. Continue until the fog lifts and visibility significantly improves.

• If you decide to anchor your vessel and shut off the engine, the sound signals change. While you are at anchor you must rapidly ring your bell for 5 seconds at intervals of not more than 1 minute. This lets other vessels know where you are and what your status is.

Sound Signals and Restricted Visibility

Last but not least, sound signals! Sound signals are a rudimentary form of communication and have been around since Fred Flintstone squeezed a Pterodactyl strapped to the top of his car. Since then, horns and whistles have evolved and their use for navigational sound signals falls into one of two categories: signals used when in sight of other vessels and signals when not in sight of other vessels. The majority of recreational boaters don’t understand how to apply these signals and in most cases avoid using them. I’ve heard several reasons for the lack of use by recreational boaters, such as they confuse other vessels in the area, or “Other boaters don’t use them, so why should I?” But mostly it’s just not part of the culture. Realistically, if you are paying close attention and have good situational awareness, you shouldn’t have to use sound signals in all but close-quarter situations.

All vessels, motorized or non-motorized, are required to carry a sound-producing device or as defined in the rules, a “whistle.” In Rule 33, the word whistle means “any sound signaling appliance capable of producing the prescribed blasts and which complies with specifications in Annex III to these Rules (33 CFR part 86).” So a horn or whistle, manual or mechanical, that can produce an audible sound, is required. For vessels under 12 meters, 39.4 feet, there is no specific audible range listed. Vessels over 12 meters but less than 20 meters (65.6 ft) must have a half-mile audible range. Realistically you might only hear a sound signal from another small vessel when within 100 yards so this is why you should closely adhere to Rules 5, 6, 7 and 8,  by establishing a risk of collision in plenty of time where simply maneuvering early will remove the risk. Again, if you mitigate the risk early enough, sound signals may not be necessary. Regardless, recreational boaters should know the basic signals and make every attempt to use them when the situation warrants.

I made a promise in my first article that I was going to stay away from international rules because they are so similar to inland rules that the differences would just be confusing, but sound signals are not one of those instances. First, we need to discuss where the boundaries are between international and inland rules. The boundary lines are charted and also listed in the Code of Federal Regulations. They are also listed in the back of the navigation rules book. These boundary lines are called lines of demarcation, normally a line one can infer between jetty tips or headlands on smaller estuaries where coastal waters transition to inland waters. Larger bays and sounds will normally remain under international rules, so it is always best to check which rules apply in the waterway you intend to use. The difference between the two is that under international rules your maneuvering signals are signals of action whereas under inland rules maneuvering signals are signals of intent. For inland rules, if risk of collision exists and you sound one short blast of the horn, you are intending to bring the other vessel down your port side, turning to starboard. The other vessel would repeat that signal to indicate that it understands and the maneuver is made. International rules are signals of action.  If you’re in international waters and risk of collision exists or if you’re in a waterway or channel and turning into the direction or possible path of other vessels at a bend or channel entrance, the maneuvering signals are sounded and the maneuver completed. There is no requirement for the other vessel to respond.

For recreational vessels in inland waters, the signals are pretty basic and easy to remember because there are only two: a short blast and a prolonged blast. The term short blast means a blast of about 1 second’s duration. The term prolonged blast means a blast from 4 to 6 seconds in duration.   These can be in different combinations, but if you separate those signals that are used when in sight of another vessel and those when not in sight, it becomes very easy. Let’s talk about when vessel are in sight of each other; Rule 34. No matter the situation, always think, “If I sound one short blast, it means I intend to turn to starboard and bring the other vessel down your port side.” Similarly, two short blasts turning to port and bring the other vessel down your starboard side. That’s it! You have just graduated the “signals when vessels are in sight of one another,” course.

As with any of the rules, there is a fail-safe clause known as the “Danger Signal.”  When doubt exists as to the intentions of the other vessel, you should sound 5 or more short blasts in rapid succession:  (d) When vessels in sight of one another are approaching each other; and, from any cause, either vessel fails to understand the intentions or actions of the other, or is in doubt whether sufficient action is being taken by the other to avoid collision, the vessel in doubt shall immediately indicate such doubt by giving at least five short and rapid blasts on the whistle. So if you are in a situation where the risk of collision exists and you are unsure, or the other vessel operator is unsure, of what’s taking place anyone can sound 5 short blasts of the horn.  When you hear that signal, it means that you should take immediate action, under the applicable rule for that situation, and maneuver accordingly. Assuming that the signal does not apply to you could be a deadly assumption.

If you can make contact with the other vessel on the VHF radio and agree on how to pass each other, then whistle signals are not required. (h) A vessel that reaches agreement with another vessel in a head-on, crossing, or overtaking situation, as for example, by using the radiotelephone as prescribed by the Vessel Bridge-to-Bridge Radiotelephone Act (85 Stat. 164; 33 U.S.C. 1201 et seq.), is not obliged to sound the whistle signals prescribed by this Rule, but may do so. If agreement is not reached, then whistle signals shall be exchanged in a timely manner and shall prevail.

Operating in restricted visibility has the highest factor of risk that you will encounter while recreational boating. Great care and alertness should be a priority and unless there is some greater compelling reason to be underway, it’s probably best to remain at the dock until conditions improve. The worst-case scenario as far as restricted visibility goes, would be fog. But in the case you are caught up in the fog, your awareness should be heightened.  Before we get into Rule 35, we need to go back to establish the conduct of vessels operating in restricted visibility before addressing the signals required.

In Rule 19, vessels have a specific responsibility when navigating in or near an area of restricted visibility.  In a nutshell, it is a rule of detection and avoidance where the rules for a vessel in sight of one another don’t apply. Rule 19 is about reducing risk.  We know the audible range of a sound signal is approximately one-half mile. So you can surmise that if your visibility is less or close to a half-mile then it is an appropriate time to take this rule into account. What do you do? First, slow down; (b) Every vessel shall proceed at a safe speed adapted to the prevailing circumstances and conditions of restricted visibility. A power-driven vessel shall have her engines ready for immediate maneuver.  You have to fall back to the basic rules for vessels operating in all conditions of visibility. That would be Rules 5 through 8. Maintain a proper lookout and use passengers to help you observe, through sight and sound, what is happening around you. Make sure that lookouts (your passengers) are properly briefed and that their attention is solely focused on detecting the presence of other vessels in the area. Never assign lookouts to other tasks. Their focus should only be toward detecting other vessels so you can determine if a risk of collision exists.  You should also operate at a safe speed for the prevailing conditions so that you can take proper and effective action to avoid a collision if necessary. Never operate at a speed where you are unable to stop within a distance appropriate to the prevailing conditions.  A good rule of thumb is to be able to stop within your boat’s length. Use all available means to determine if the risk of collision exists. Most importantly, if the circumstances of the case admit, you shall take positive action in ample time with the due regard to good seamanship to avoid a collision. So navigation lights on, slow down, post lookouts determine if a risk of collision exists, even if you can’t see the other vessel, and take action to avoid a collision.

 So how do you avoid a collision if you can’t see the other vessel?  (e) Except where it has been determined that a risk of collision does not exist, every vessel which hears apparently forward of her beam the fog signal of another vessel, or which cannot avoid a close-quarters situation with another vessel forward of her beam, shall reduce her speed to the minimum at which she can be kept on course. She shall if necessary take all her way off and, in any event, navigate with extreme caution until danger of collision is over. 

So let’s say you have radar. (d) A vessel which detects by radar alone the presence of another vessel shall determine if a close-quarters situation is developing and/or risk of collision exists. If so, she shall take avoiding action in ample time, provided that when such action consists of an alteration of course, so far as possible the following shall be avoided:

(i) An alteration of course to port for a vessel forward of the beam, other than for a vessel being overtaken;

(ii) An alteration of course toward a vessel abeam or abaft the beam.

So in order to make this happen, we need to go back to the sound signals used when vessels are not in sight. Rule 35  As a power-driven vessel underway, you only need to concern yourself with two signals. Underway and making progress (make way), would be one prolonged blast (4 to 6 seconds in duration) of the whistle every two minutes. If you are stopped and drifting or not making way, you sound 2 prolonged blasts every 2 minutes with a one-second interval between blasts. That’s it!  If everyone is following these rules, you should be able to tell what direction another vessel is from you and how close they are. If the sound is coming from a constant direction and is getting louder you are likely at risk of collision. Slow down or stop.

If you hear any other signals such as one prolonged and two short or one prolonged and three short, all you need to realize is you need to stay clear of that vessel and follow Rule 19 above. Vessels sounding those signals are higher in the hierarchy (Rule 18) and you would be required to avoid them even in good visibility. For those with radar, if you detect any vessel ahead or forward of your beam turn to starboard. If the other vessel is abeam or aft of you, do not turn toward it and continue to monitor your radar and adjust as things change. In any situation, good or bad visibility, if you are uncomfortable or unsure of the situation STOP. Monitor the movement of the other vessel and take the best course of action necessary to avoid a collision.

Hopefully, you can see that there is nothing mystical about sound signals.  My persistent message throughout all of these articles is if you can identify the risk of collision early, make a reasonable course adjustment to remove the risk of collision, you will probably never use sound signals. When you determine that risk of collision exists, letting people know your intentions,  or in the case of restricted visibility, notifying them of your presence with sound signals is merely being a safe and responsible boater. Staying focused on the safety of everyone on the water should be your primary concern. This is also the reason why we have and should follow all the rules of navigation. The rules benefit all boaters and waterway users. It’s never wrong to ask someone to help interpret the rules if you don’t understand them. To disregard them can be a costly or fatal mistake.

As a final thought, no matter the situation, the vessel Captain has the ultimate responsibility for safe navigation. Whether it is a kayak or a superyacht, the responsibility and liability falls on their shoulders.  Having a working understanding of the navigation rules is the single most important skill a boat operator can learn. Always remember, “Superior Mariners use their Superior Knowledge to avoid situations that require their Superior Skills.”

By: Dan Shipman, Recreational Boating Safety Specialist

13th Coast Guard District