A boater with his navigtion lights activated
A boater with his navigtion lights activated

Navigation Lights - See & Be Seen

Foundation Findings #48 - January 2010

In 1990, the BoatU.S. Foundation evaluated running lights, judging color, intensity, and arc of illumination. Running lights, which are generally installed by manufacturers, are Coast Guard certified for color, arc of illumination and distance.

Since it has been nearly 20 years since our initial test, we wanted to take a fresh look and evaluate the visibility of a typical recreational boat's running lights at the distances for which they were rated, and we also wanted to look at LED lights, which were not available for our first test.

There is no requirement for a boat manufacturer to install running lights on modern boats, but if they do they must use US Coast Guard (USCG) certified fixtures and installed per regulations. However, it is ultimately the boat owner's responsibility for the proper display of navigation lights and owners should take note if purchasing a used boat, especially if fixtures have been moved to accommodate additions like T-tops or bow pulpits. At the end of the day, it is your responsibility to be certain your lights are positioned properly and are the proper intensity for your sized boat. To see USCG minimum requirements, click here (opens in new window).

We tested more than two dozen weather products on the market - everything from cellular phone text messaging to Sirius satellite weather on a chart plotter. For the purpose of this test we did not examine offshore communication methods such as satellite phones, Inmarsat or weather fax products but focused on weather products available to inshore and near coastal boaters at nominal prices.

In both tests, we found that even properly installed, Coast Guard certified lights can blend with background lights from other geographic features or get lost in the myriad of other possible light sources often called "backscatter." Sometimes backscatter even reflects off the water, making it difficult to determine exactly how many lights you are seeing. Reports of these challenges, as well as complaints about glare may leave many wondering if there are easy solutions to help the average recreational boater "see and be seen."

This test did not compare manufacturer's products head-to-head. Instead, we evaluated the lights that came factory-installed on our 11-year-old center console test boat. We then replaced them with a handful of new lenses, new fixtures, and some readily available portable LED lights to see what simple modifications can be made to improve the visibility of your boat at night, and to reduce on-board glare that can affect nighttime operators.

Test Background - Do You See What I See?

The Findings test focused on observations relying on the naked eye and spoken commentary from our volunteer test subjects. Observers ranged in age from the mid-twenties to mid-fifties. One observer was color blind. All are boaters and have previous nighttime experiences on the water. Our tests were not vision tests per se, nor were they intended to specifically verify manufacturers' claims. Rather, the tests focused primarily on visibility - more precisely, determining whether the lights could be easily recognized and identified at the distance for which they were intended.

A full moon is not much help with this pitch black sky.

A nearly full moon presented more problems than expected when light reflected off the rippling water causing observers to question what they were seeing.

On the night of our testing, we had calm sea and wind conditions, a nearly full moon, and good visibility. Ideal conditions for nighttime boating and one would think, for nighttime observations and testing. We found, however, that with such calm and clear conditions, running lights and navigational aids reflected off the water, literally causing us to see double at times. The moon cast light on the water, and its reflections were multiplied by ripples and boat wakes. The lights of houses, docks, bridges - even passing cars also further distracted our observers.

It is worth noting, however, that our observations may have been significantly different on a pitch black night-or out at sea.

Test Background - Do You See What I See?

We set out to answer these simple questions - how well can you see the light at various distances? What factors played a role in a boat's visibility? Navigation lights are barely visible at night from a distance.And is there anything within reason that can be done to improve visibility so that others can see you and you can see them?

To carry out our test, we anchored a large power boat as our observation platform. Our test boat, a 22' center console power boat, had a combination red and green light mounted on the bow and an all 'round white light mounted on a 12" pole on top of the T-top. We outfitted each fixture with pin fittings so we could quickly connect and disconnect the various lights. We then moved the test boat 0.5 mile, 1 mile, 2 miles and 3 miles away from the observation boat and recorded feedback from the observers at each interval.

Many bicolor navigation lights on display at night.

We evaluated each of the following products:

  • The original lights that came standard with our eleven-year-old boat. Perko, bi-color $35.99. white $62.99 (The plastic lenses had an obvious weathered and slightly clouded look during a close-up visual inspection.)
  • The original lights with new replacement lenses that cost about $15 for each fixture. Perko, bi-color $12.49, white $14.99
  • A new single bulb LED light fixture Attwood, bi-color $52.99, white $96.98
  • Two multiple bulb LED fixtures:
    1. Portable multiple bulb LED fixtures for both the bow and stern light - NaviLight, bi-color $49.99, white $49.99*
    2. Portable Navigation Lights for small boats less than 7 knots - Aqua Signal, bi-color $34.99, white $34.99**
Lenses and light bulbs for navigation lights

*NaviLight portable lights require 3 "AAA" batteries. Not Coast Guard certified, but meets lighting requirements for boats under 12 meters (39').
**AquaSignal portable lights require 4 "AA" batteries and are for use on crafts less than 7 meters (22 ft.) in length and a maximum speed of 7 knots (8 mph).

A Word About LEDs

Relatively new to most consumers and far from standard on boats are LED (light emitting diode) lights. Though you've seen them on your stereos, TVs, DVD players and just about any remote control for years, consumer fixtures are a relatively new application for LEDs. Using semiconductor technology, these lights present many advantages over incandescent lights, especially for boaters.

A close-up of a bi-color, bow navigation light.

According to experienced cruisers, the primary draw of LED lights on a boat is that LEDs are more energy efficient. They draw less energy and have a long life expectancy, which makes them great for anchor lights. The same bi-color light at night.They also generate less heat and are directional in output, providing a narrow beam of light perfect for a flashlight or a reading light fixture. However, this directional output means that a single LED cannot effectively fill the required arc of a navigation light or the requirement for an all 'round 360 degree light. Fortunately, newer multi-bulb LED fixtures have emerged on the market to help achieve the arc effect.

A close-up of a bi-color, bow navigation light.

There are of course larger LED fixtures on the market but we didn't evaluate them as our focus was on the smaller recreational boat. LED arrays clearly have their advantages. 2 white stern lights side by side. LED on the Right and a traditional incandescent bulb on the left.Their low-energy draw makes them ideal for anchoring and thereby extends battery and alternator life. LED bulbs are also long lasting and have sealed circuitry. Manufacturers often claim 50,000 hours of useful life and some offer warranties up to 10 years. The only disadvantage is that the cost of the fixtures may not seem to pay for itself initially. But down the road, it could pay dividends. And seeing and being seen by other boaters is, well, priceless.

Although LEDs are comparatively more expensive, we were curious if there was a visible difference when compared to standard incandescent lighting fixtures. We tested these fixtures both on the water and with a light meter in an indoor controlled setting.


The original lenses on our test boat had become clouded over the years, and were observed as being "washed out." A yellow colored light meter is used to test the luminosity of a white stern light.At 2 NM, the green light looked white and at 3 NM, white looked "reddish" according to some observers. As expected, by simply replacing the 11-year-old cloudy lenses with new lenses, observers reported that the lights could be seen much better. The white light benefited the most with a new lens. The red and green were greatly improved too and the color was truer at all distances.

Next, we replaced the fixture with the new lenses with a brand-new red/green combination LED fixture. We selected a readily available fixture that used a single red and a single green LED bulb behind a clear lens. Various manufactures have stated that a white LED bulb behind a colored lens is not recommended. (Typically, navigation light fixtures use a traditional white filament bulb behind colored lenses.)

A yellow colored light meter is used to test the luminosity of a white stern light.

At close range and up to 0.5 mile, the LED lights looked brighter and crisper, with some commenting that the white light looked somewhat blue, almost like a fluorescent overhead street lamp on shore. At greater distances, testers agreed the white LED sometimes got lost in the backscatter, but up close without the confusion of backscatter, the white LED light had a distinctive look. This is due to how LED lights are made-a white LED bulb doesn't emit the same type of light as a traditional bulb, and the light doesn't appear as 'warm' or natural as a traditional bulb.

A Bright Finish - Multi-LED Fixture

We hesitated to purchase any light that was not Coast Guard certified for our evaluation. But when an email from a parts retail supplier literally arrived the day we were headed out on the water, announcing the arrival of a new LED navigation light, we stopped by to pick it up. The NaviLight uses an array of 16 tiny individual bulbs to complete the required arc of illumination. This fixture was also portable, requiring just 3 AAA batteries.

Mutli-bulb LED fixtures are not new in the transportation and retail world. You see them in brake lights on cars and lighted signs for businesses. Some larger boats even have multi-bulb LED fixtures, but they cost hundreds of dollars. Our NaviLight setup cost about $100 for both the bi-color and white light, so we hoped that investment would prove valuable. And to our delight, it performed very well - a real surprise since the product targets the operators of small marine craft like tenders, dinghies and paddle craft.

On average, this fixture outperformed every light fixture we evaluated. At close range, one observer stated that the lights were "big", meaning their aura was large. And at 3 NM, another observer stated that the red and green LEDs were almost as bright as the large government maintained red and green lighted Aids to Navigation.

A white all-around stern light illuminates a dark background.

A note about color:

There are four critical factors that determine the distances at which light can be seen: the intensity of the light (candlepower), its color (chromaticity), the height of the light above the water, and your height above the water. Green is the easiest color to see at night. Red is used for navigation lights because its wavelength is the longest of all colors and it is easily recognized by the naked eye.

Some Final Thoughts

A boat's running lights tell much about the night time operation of a vessel. For example it can indicate if the vessel is a sail boat or power boat, if you're looking at its starboard or port side, or if its coming or going. For larger boats, lights can indicate certain commercial maneuvers such as if a vessel is tugging or pushing a barge, if it's engaged in commercial fishing or dredging, or if it is aground or at anchor. Recognition and maintenance of these lights is paramount to everyone's safety on the water.

For as much as running lights can tell you about a boat and its operation, there's much that can't be gleaned from a passing glance. For example, it is often difficult to determine the true direction and range of another boat. When operating at night, the same Navigation Rules apply as well as the Coast Guard requirement for maintaining a proper look out and operating at a safe speed. Taking bearing readings on other objects and vessels is also important and could mean the difference between a near miss and a safe passage.

A dual console powerboat makes way with running lights luminated.

Your eyes need anywhere from 12 to 40 minutes to fully adapt to the dark after exposure to bright light. Boating at night requires preparation, focus and concentration. Here are some additional tips to make your nighttime outing a safe one.

It Goes Without Saying:

  • Maintain a proper lookout
  • Reduce your speed at night
  • Follow the Rules of the Road
  • Always wear a properly fitted PFD
  • Get well rested before nighttime operation
  • Let your eyes adjust properly to the conditions
  • Never consume alcohol prior or during operation
  • Extinguish other lights that might contribute to night blindness

Tips to Reduce Onboard Glare:

Night blindness is sometimes caused by the operator's own vessel. Your boat should be set up so that on board lighting does not interfere with safe nighttime operation.

  • If you have any doubt, be certain your light fixtures are mounted properly per Coast Guard requirements. For example, an all 'round white light should be 1 meter higher than the red and green fixture.
  • An all 'round white light is often mounted on a pole to meet the requirement above. For most runabouts, a removable pole mounted light ranges from 4" to over 4'.
  • Stern lights should not "spill" or allow stray light into the cockpit. However, an aftermarket glare shield resembling a pie-plate placed underneath an all 'round white light can greatly reduce on board glare.
  • Light fixtures should also be mounted such that chrome grab rails, cleats and other shiny surfaces don't reflect light back into the operator's eyes. A temporary fix is to place black electrical tape on shiny surfaces to prevent reflection.
  • Check to see if lighted instruments and electronic navigation equipment can be dimmed. Our GPS Chartplotter had a nighttime display mode that cut glare by over 50% when measured by a light meter.

Tips to Increase Visibility

In our observations, we were able to make some general conclusions about the products and have compiled a list of tips that can help visibility when operating a boat at night.

  • Assure that all fixtures are working properly by checking prior to departure and replace any burned out bulbs. You should always carry a spare or two.
  • Clean all light lenses with something soft once a season. Grime and insects can sometime build up on the inside too.
  • Inspect lenses for fading, crazing, or cracks that might affect light output. Our eleven-year-old lenses were cloudy, reducing overall effectiveness.
  • Replace any broken or faded lenses with new ones. This is a simple fix and it really makes a difference.
  • Be certain light fixtures are mounted properly. The white stern light should be placed high enough so that it does not cause operator blindness.
  • On average, LED lights were more visible than comparable incandescent fixtures. Although more expensive, LED lights draw less energy and have a much longer life expectancy.

Basic Requirements for Small Boats

In general, a boat is required to display navigational lights from sunset to sunrise and in or near areas of reduced visibility. While underway, no other lights may be displayed that could be confused for a navigation light.

For power boats under 12 meters (39 feet) the red and green sidelights (or combination red/green single fixture) must be visible for 1 nautical mile (NM) and the all 'round white masthead light or stern light must have a visible range of 2 NM. This includes sailing vessels under power and motor sailing.

Boats larger than 12 meters but less than 20 meters (39-65 feet) have a 2 NM requirement for side lights, a 2 NM requirement for stern light and 3 NM requirement for masthead light. A sailboat under sail alone does not have the 3 NM requirement for the masthead light. At anchor, both power and sail less than 65 feet must have a 2 NM all 'round white light. For an interactive lighting requirement diagram check out the Coast Guard's Navigation Center.