Light Up The Night

By Daniel Rutherford

The right navigation lights are essential to safe piloting after dark.

Photo of aftermath of a collision between a sailboat and a powerboatThe aftermath of a collision between a sailboat and a powerboat seven miles east of Bethany Beach, Delaware in July 2012. (Photo: Petty Officer Jennifer Williamson, USCG)

Let's consider a scenario for a minute. You're heading out across the lake for a night of fishing. You have your navigation lights on. You are at the wheel and you have one of your crew members watching the horizon for any signs of vessels ahead. It's a big lake and it's dark, very dark. Perhaps you slow down a bit, but there is no "restricted visibility" so you are still moving quickly. Suddenly, out of nowhere, you strike another vessel and two people are killed. What went wrong?

This scenario actually happened, one of many tragedies I have investigated as a marine surveyor specializing in accident investigation and reconstruction. In this case, the boat that was hit was drifting, motor off, lights off, in the middle of the lake. That's right, no lights. They were off to make it easier to gaze up at the stars. That simple mistake turned into a tragedy. Many of the cases involving collisions at night that I have investigated and that result in serious injuries or even deaths could have been prevented with the correct navigation lights used properly.

COLREGS And Night Navigation

The International Regulations for Preventing Collisions at Sea (COLREGS) is akin to the Bible when it comes to safety at sea and assessing the risk of collision. The COLREGS supply us with a well-tested set of rules to live by, including those governing navigation lights. If you, as a fellow boater, haven't read the COLREGS — not a very difficult or time-consuming process — please do so before you hit the water this season, for my sake, as well as your own.

I hope we all know the basic "Rules of the Road" by now. For instance, if you and another vessel are approaching each other and are "in sight of one another", the boat forward of you and to starboard is the "privileged vessel", which makes you the "burdened vessel" in a collision scenario — you must keep out of their way. Conversely, if you have a vessel ahead of you to port, you are the "privileged vessel" and they are the "burdened vessel." These common situations are easy to see during daylight. But in the dark, the only way to see a boat and tell what direction it is moving is by its navigation lights. COLREGS define what navigation lights must be used at night and in restricted visibility so the same collision avoidance procedures can be taken.

COLREGS Part C - Lights and Shapes defines the lights and shapes that must be carried by different vessels in different conditions. First and foremost, the "Rules of this part shall be complied with in all weathers" from "sunset to sunrise" and "during such times no other lights shall be exhibited." The COLREGS even go so far as to say that "The lights prescribed by these Rules shall, if carried, also be exhibited from sunrise to sunset in restricted visibility." Bottom line? If it's hard to see, your navigation lights should be on.

Illustration of Navigation Light Requirements For Boats Over 16 FeetNavigation Light Requirements For Boats Over 16 Feet. (Source: West Marine)

Let's return to the situation we started with — the boat floating on the lake with no lights in the dark. This example helps to illustrate the COLREGS as an intertwined set of rules. Was the drifting vessel (motor off, not anchored) a vessel "underway"? Were they required to "post a lookout" per the COLREGS? Were they required to "take action to avoid collision"? Were they required to display their navigation lights? The answer is "all of the above." If they had taken the required steps, it's likely that there would have been no collision and two lives would have been spared. Unlike cars that need headlights to see, as mariners we count on navigation lights to allow us to be seen.

Part C — Lights and Shapes not only defines when we should be displaying our navigation lights, but it also defines the types of lights, placement of the lights, colors of the lights, and intensity of the lights. For instance, if I were to ask you where your masthead light was, you might say, "At the top of my mast." Well, you might be wrong. That light is probably your all-round light that you use when you're anchored. Your masthead light, for those sailors in the crowd, is the light on the forward side of your mast that should show an unbroken white light over an arc of 225 degrees. For powerboaters, your masthead light is the same 225 degree arc carried probably on the forward side of your flybridge or on a short staff under your all-round light. Boats under 12 meters (about 40 feet) can carry one all-around white light that serves as both masthead and stern light. Power-driven vessels (which also means sailboats when motoring) must display this light when underway.

Photo of an obsurred side light on bass boatThe trolling motor mounted here almost completely blocks the green sidelight, rendering it useless. (Photo: Daniel Rutherford)

The red and green lights carried forward are called sidelights. Sidelights each have an arc of 112.5 degrees "so fixed as to show the light right ahead to 22.5 degrees abaft the beam on its respective side." Notice that both lights together cover an arc of — you guessed it — 225 degrees. When you combine your sidelights with your masthead light, an approaching vessel from forward of 112.5 degrees will see either a red light with white above it (if approaching from the port side) or a green with a white above it (if approaching from the starboard side). If you see red, you're likely the burdened vessel, and if you see green you're likely the privileged vessel, just as if you could be seen in daylight.

Navigation Light Mishaps

So what can go wrong with navigation lights? How about a combination red/green sidelight on the bow that is obscured by an anchor hanging off the bow rail? Or a combination bow light that was properly mounted on the bow of a bass boat by the manufacturer, only to have the dealer install a trolling motor bracket that blocked the starboard side of the light? How about sidelights that were installed on the radius of the deck of a boat so that the arc of visibility for the lights were at 45-degree angles rather than across the horizon? These are all real examples that resulted in tragic accidents.

When approaching a vessel from a direction more than 22.5 degrees abaft her beam (from astern), you should see only one white light, the stern light, which makes you the burdened vessel. Stern lights cover the other 135-degree arc that sidelights don't — you can't see both stern lights and sidelights if they are properly mounted. But what if the stern light is blocked by a man-overboard module (MOM) or Horseshoe/Type IV throwable device, or laundry drying on the rail? That one obscured light, if it results in a collision, might cost your life or someone else's.

Photo of a man overboard module blocks stern lightThis man-overboard module prevents the stern light from being seen from the port side. (Photo: Daniel Rutherford)

One last case to help illustrate just how important the proper display of navigation lights is: In 2012, there was a collision between a sport-fisherman and a sailboat off the coast of Delaware. (opening photo) It was a dark, almost moonless night, but the weather was clear and visibility was unlimited. Both vessels were equipped with and operating their radars, and both vessels were equipped with and running their navigation lights. But somehow they found each other in that big ocean, the powerboat colliding with the port bow of the sailboat, resulting in injury.

The investigation revealed that the powerboat's navigation lights were all energized and properly displayed. The sailboat was fitted with all required lights and she was under power, meaning she had to show the lights of a powerboat. She had, just prior to the collision, switched on all of her navigation lights. Unfortunately, the investigation also revealed that the stern light was mounted in such a position as to be obscured from the port side by a MOM and there was evidence to show that the combination bow light may not have been illuminated because one of the wires leading to the light at the base of the bow rail was corroded and had parted. This case went to court and settled on a mutual fault basis showing that despite the burdened vessel (the powerboat in this case) not giving way, there was fault attributable to the privileged vessel (the sailboat) because she, too, was in violation of a navigation rule.

See And Be Seen

Now that you know how dangerous incorrect or inoperative lights are, here is what I suggest you do at your first nighttime opportunity. Take your boat out to a safe anchorage, turn off all of the deck and cabin lighting, and turn on all of the navigation lights. From a dinghy or another vessel, circle your boat and make sure that all of your lights are in compliance with the COLREGS.

First, see if they are all working. If not, check the wiring connections to the lights. Make sure those connections are clean, intact, and watertight. Check the bulb and filament. If the bulb has a cloudy appearance, a loose filament, or any indication of burning, replace it. Check the bulb contacts and clean them (a small piece of emery cloth is perfect for cleaning the contact surfaces). Now make sure that the light is mounted correctly so that it projects the proper arc of visibility.

Photo of a combination sidelight obscured by roller furlingThis red/green sidelight is barely visible on deck, let alone by someone on another boat. (Photo: Daniel Rutherford)

Next, check to see that they are bright — most nav lights have to be seen from two miles away. If they seem dim, remove the light's lens (if possible) and check to be sure that it is clear and not hazed over by UV degradation. Often, lights mounted on rails are hung by straps or fittings that allow the light to sag downward over time. The lens needs to be perpendicular to the waterline unless otherwise stated in the mounting instructions. Perhaps most importantly, is there anything hanging over the light or obstructing its full arc of visibility? Navigation lights are useless if they can't be seen.

Each time before you venture out at night, don't just flip the switch and assume the lights are on. Visually check and examine the lighting to make sure it is both on and visible. Remember, your navigation lights are how you are going to be seen (or not seen) by others. 

Daniel K. Rutherford is president of Ocean Marine Specialties, Inc., a marine consulting firm that specializes in marine accident reconstruction and claims investigations. He is a Certified Marine Investigator and Licensed Private Investigator. He has been investigating marine cases for over 30 years.

— Published: July 2014


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Nav Light Resources

US Coast Guard Navigation Center. Includes all COLREGs, searchable by subject and with flash cards for practice.

BoatUS Foundation Online Course Animations. Click on the different animations to see if you'd know which type of boat you were seeing based only on the lights.