Navigation Rules of the Road -Series VI

The Importance of Lighting

Call me a nerd, but I love navigation lights.  When you look through this section of the rules there is a festival of different lighting configurations from skiffs to submarines and everything in between. If you’re following along through the previous articles you may have noticed that there is always the overreaching basic set of rules that apply to everyone regardless of vessel type or service. The same thing holds true for navigation lights. For the recreational boater, it’s pretty simple, you need a mast light, stern light and green and red running lights (Figure 1). That’s it, we’re done, short article! You know I’m not going to let you off that easy because there is a lot that needs to be explained because the devil is in the details when it comes to navigation lights.

Figure 1, the correct mast, stern, red and green running lights.

Looking through the rule book you might ask yourself, why are there so many different light configurations? To answer that question you have to look back at Rule 18 covering the hierarchy of vessels.  Simplistically, other vessels displaying more or different lights than you are higher in the hierarchy in Rule 18.   So if they have more lights than the standard lighting configuration you automatically are the give-way vessel. I’m not going to attempt to address all the different lighting configurations because it will only be confusing and I want to keep this reasonably short and to the point but if you want to get into depth on lighting for vessels not under command, fishing, trawling dredging, etc., you can reference the actual rules, NAVRULES.

There is always an exception and the general lighting configuration -Figure 1 is no different, but those differences are due to the physical size of the vessel. As vessels get smaller there is less room available to display these lights at the distance of separation required in other parts of the rules. Power-driven vessels of less than 12 meters in length (39.4 ft) do not have to display an individual stern light but may instead, display a 360 degree all around white light (Figure 2).  The majority of recreational vessels display this alternate lighting configuration.

All vessels must display the basic lighting configuration. The additional lighting required for vessels higher in the hierarchy is only displayed when they are actively engaged in whatever activity places them in a special status. Once their status changes, they revert back to being a power-driven vessel underway. Bottom line, a recreational boat will only display basic lights required by all vessels.  That said, there is still much more that the average recreational boater needs to know about navigation lights.

Figure 2, bow and all-round white light configuration for small recreational boats.

When are navigation lights required?  As always, consult the rule of applicability for that section of the rules. Rule 20, (a) Rules in this subpart (Rules 20-31) (§83.20 through §83.31) shall be complied with in all weathers.

(b) The Rules concerning lights (§83.20 through §83.31) shall be complied with from sunset to sunrise, and during such times no other lights shall be exhibited, except such lights as cannot be mistaken for the lights specified in these Rules or do not impair their visibility or distinctive character, or interfere with the keeping of a proper lookout.

Translation: when you are running at night or in restricted visibility you should not be showing any lights other than the navigation lights required. The exception noted is that if you have other lighting on board it cannot have the characteristics of the lights required by the rules; red, green, white or amber. Non-navigation lights cannot be positioned or be so bright that they obscure the required navigation lights or they create so much glare that they impair the ability of anyone on board from being able to see in the course of standing a proper lookout.

I know what everyone is thinking, “What about the big honking floodlights almost everyone has on their boats?” In Rule 36, Signals to Attract Attention, a vessel “may direct a searchlight in the direction of danger in such a way as to not embarrass any vessel”. This rule would allow such lighting but, if you have floodlighting installed you should not use them like headlights on a car. Turn them off when approaching other vessels so that you do not compromise their night vision or obscure your navigation lights. The bright light basically blinds and disorients others just like someone shining a flashlight in your face. Normal night vision only returns after the light has been extinguished and the eyes have had adequate time to readjust. I have had a personal experience with just that type of situation and in fog or reduced visibility and it is dangerous. It’s all about respect for the other guy. Give them a break and turn the lights off until you’re well clear.

Back to why they are required, (c) The lights prescribed by these Rules shall, if carried, also be exhibited from sunrise to sunset in restricted visibility and may be exhibited in all other circumstances when it is deemed necessary.

So it’s not just after the sunsets. When you encounter rain, sleet, snow, hail, fog and dark of night your navigation lights should be used. Even smoke if there is enough to restrict visibility. So navigation lights are one of the most important pieces of equipment you have on your boat when it’s dark or visibility is compromised. They alert others of your presence and provide a snapshot of your activity.

Let’s review the light characteristics themselves. In Rule 21, definitions, all vessels under 39.4 feet in length are required to have an all-around white mast light (360 degrees) and port and starboard running lights, 112.5 degrees each. The all-around white mast light incorporates the stern light so that it can be seen in a 360-degree arch (Figure 2). Vessel over 39.4 feet must have a separate mast and stern light that must cover that same 360 degree arch with the mast light being seen in a 225-degree arch forward. The masthead lights arc of visibility is exactly the same as the combined arc of visibility of the port and starboard running lights. In this configuration, the stern light covers the remaining 135 degrees aft (Figure 2). Regardless, if you are over or under 39.4 feet in length other vessels will see the white light approaching from any direction (Figure 3). Pretty standard display with some minor exceptions when it comes to vessels under sail, Rule 25, where the mast light is not required.

Figure 3, correct placement of bow lighting and angles of visibility.

Federal recreational vessel manufacturer requirements make the proper placement pretty standard but we continually find new boats where the lighting is not correctly placed. Hopefully, I will be able to explain what to look for and your responsibilities in making sure the proper lights are displayed in the proper configuration. There are some very specific standards that navigation lights must comply with in order to meet visible distance requirements and prevent bleed over so that each lights sector is precisely defined from the others. In Rule 22, Visibility of Lights, For recreational boats under 39.4 feet in length the lights prescribed in these Rules shall have an intensity as specified in these Rules (33 CFR part 84), so as to be visible at the following minimum ranges: A masthead light, 2 miles; A sidelight, 1 mile; A stern light, 2 miles.

So now we have entered the mystery section in the rules, buried back in the dusty pages, where no one ever looks. These are known as the annexes! This is where the technical details of navigation lights; whistle signals and other information pertaining to them hide. Most of the rules we deal with are concerned with the operation and display of the signals.  Here is where you find the technical details of how they are constructed and function. There are specific chromaticity (color) standards. Minimum luminous intensity and most importantly the horizontal and vertical sectoring.

This is important because if you could put any old light any place you want, the uniformity in clarity, color, and sectoring to distinguish what the lights represent, would be lost. Vertical and horizontal sectoring of lights is the most important part of these standards. Horizontal sectoring ensures that the moment you can see the color change from one light to the next, you realize your relative bearing has changed. So if you were standing out in directly in front of your boat you should see both red and green lights. Step from one side to the other you should see either the red and green lights, depending on which side you choose to move, quickly disappear. You should only have to move one to three degrees of arc for that to happen. Three degrees is a very small zone. (a)(i) In the forward direction, sidelights, as fitted on the vessel, shall show the minimum required intensities. The intensities shall decrease to reach practical cut-off between 1 and 3 degrees outside the prescribed sectors. The intensity of the light has a significant part in the correct sectoring of lights. If the light is too bright or intense it can bleed over and or virtually eliminate the sectored separation between other lights.

How and where you mount navigation lights can also affect the horizontal zone.  If the lights are not mounted parallel to each other and pointed directly ahead the zones will cross making them visible further outside the lights intended sector. This gives a false representation of your exact heading and can greatly increase your risk of collision.  This not only affects your perspective but if your display is incorrect, it affects other boater’s ability to correctly assess what direction you are going and increase the risk. This not only affects you when meeting in a head-on situation but also when overtaking another vessel from astern. You should normally see the navigation light appear when your relative bearing is from the vessel being overtaken is 112.5 degrees relative, aft, of the vessel.  If the lights are mounted improperly, you may not see that light until you are well forward of the vessel’s beam. This increases your risk of collision in that what appears to be an overtaking situation may, in fact, be a crossing situation and you could actually be on a collision course. You can see the difference in the visual area looking at figure 3 and 4.  If the lights are improperly mounted the purple zone is where the two running light cross falsely making the vessel look like it is coming at you head-on. Note that the visual portion of the zone aft is also severely distorted.  This can pose serious problems with other boaters being able to understand your direction of movement.

Figure 4, incorrect lighting installation creating a crossover effect, increasing the risk of collision.

When you buy a new boat, the manufacture should properly place the navigation lights in accordance with Annex I and you should never have a problem.  Regardless, when buying a boat, pay attention to the navigation light placement because there could still be a possibility they could have been installed incorrectly.  The Coast Guard has contracted factory inspectors that travel around to visit boat manufacturers to make sure lights and other manufacturer regulations and standards are maintained, but sometimes boats can make it out of the shop before the inspector has a chance to inspect the facility. This is the exception and not the rule by any means. This is only an issue when lights have been mounted into the hull at the peak of the bow. These lights should be mounted parallel to each other or be in a single combination red/ green light at the peak of the bow. If not mounted correctly and the visible light sectors cross, you can have up to 30 or 40 degrees of bleed over into the other lights sector.

Mast lights are pretty simple.  Most problems with mast lighting tend to be with respect to them not being placed high enough above the vessel to be visible or blocked from providing 360-degree visibility. The other situation is when towers or radar arches are installed either by the manufacturer or aftermarket. Boaters like to place a lot of accessories on them like spotlights, speakers, radars, antenna, etc. In this application, the light should be positioned so that it is high enough above those accessories that it is visible 360 degrees when the vessel is on a plane. That height would be approximately 8 inches above the highest point on the vessel. Another problem with the aftermarket installation is that the tower is not equipped with a light mast, so if you are going to put on an aftermarket tower, insist that it is designed for a mast light and that the light is high enough that it will not be blocked by other equipment. In addition, all vessels under 20 feet in length have a removable mast head light post, just over 3 feet in length that plug into a socket somewhere on the stern. Because it gets in the way or provides some glare, boaters tend to remove them and not display the light.

The latest boating fad is putting accent LED lights just about anywhere that someone thinks looks cool. They have their place and you can really customize your boat to fit your personality but, these should not be used underway. Remember, you cannot use lighting that impairs the visibility or distinctive character of required navigation lights, or uses any lights that interfere with the keeping of a proper lookout, or be mistaken for navigation lights prescribed by the rules. Blue lights, other than those on law enforcement vessels should not be used because they can be misidentified as lights on law enforcement vessels. They look cool but they are best used at the dock or when anchored.

As of November 2012, all navigation lights manufactured and sold in the United States must be Coast Guard approved.  This means they have to be constructed and perform to meet the requirements for intensity, color, and vertical and horizontal sectoring. If you are planning on replacing or upgrading your navigation light fixtures to LED it is important that you check for the Coast Guard Approval because some LED lights, especially strip lighting, do not meet those requirements.

How do you tell if the light you are purchasing is Coast Guard approved?  On the box, you should see a label that says “USCG approval 33 CFR 183.810”.  Each light has a specific visibility rating for different sizes of vessels. Recreational vessels less than 12 meters in length, 39.4 feet in length, lights should be rated at sidelights 1 nautical mile and white mast light 2 nautical miles. On the exterior of the light fixture, each light should be marked with “USCG” followed by the certified range of visibility in nautical miles (nm), for example, “USCG 2nm”. Once installed, this mark must be visible without removing the light.

This is a lot of information on navigation lights to digest.  Hopefully, you can walk away with a better appreciation of why they exist, how they function, and when they are required to be used. Navigation lights are very important to safe vessel operation and are probably one of the most neglected pieces of equipment on recreational vessels. I always like comparing boats to cars and in the case of navigation lights that serve the same purpose as tail lights, brake lights, turn signals and flashing amber lights on a motor vehicle. They are indicators of vessel presence, the direction of travel and signal the nature of the operation. For these reasons, it is important that your navigation lights are displayed properly and that you understand them in order to make safe risk assessment decisions.

US Coast Guard District 13 LogoBy: Dan Shipman,
Recreational Boating Safety Specialist
13th Coast Guard District

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