Making the Switch to an LED Mastlight

Posted by Darrell Nicholson at 01:49PM - Comments: (9)

Ralph Naranjo
Ralph Naranjo

Practical Sailor checked each LED tri-color light to make sure that colors did not bleed into the wrong sector.

If you have your mast down this season or are contemplating an annual inspection aloft, it is a good time to consider a switch to an LED tri-color mastlight, which can cut the mastlight's energy consumption by 90 percent. Back in 2010, Technical Editor Ralph Naranjo looked at six bulbs and lanterns and compared light output and energy consumption. He also checked for interference with VHF radio reception—a common complaint among early versions of several lights.

In the past, the most popular means of meeting the U.S. Coast Guard’s navigation light requirements for boats under 65 feet (see “Nav Light Requirements,” below) was to use an Aqua Signal Series 40 tri-color lamp housing with its long-filament incandescent bulb. Its 25-watt energy appetite not only puts a significant load on the house battery bank, but it requires a heavier-gauge wire be run up the spar in order to avoid an energy-robbing voltage drop. Swapping out the incandescent bulb for an LED drops power consumption significantly and yields just as bright of a light—a great return on your investment so long as the legal requirements are met. During a 10-hour night sail, this results in reducing current consumption from about 20 amp-hours down to a scant 2 amp-hours. This savings adds up, and the extra cost of the LED bulb or light will pay for itself in longevity and energy savings.

What accounts for this great efficiency? Since the late 1960s, LEDs have followed a trend that amounts to almost a doubling of light output every 36 months. (If Wall Street had done the same, a $100 investment made in 1969 would today be worth over $500,000.) Skipping all the esoteric physics, understanding how an LED lights manages such efficiency is a simple concept to grasp: By passing a current through certain semiconductors, the electron flow results in the emission of light. Modern LEDs comprise an anode (+) and cathode (-) that meet in a tiny cup-like reflector that contains an “n” and a “p” layer of semiconductor material.

In order to achieve white or colored light, phosphor coatings are used. Another significant breakthrough is the prism-like lens and epoxy-sealed cavity that bundles up many of these semiconductors. The resulting "bulb" reflects and refracts the light energy produced, delivering a color-controlled beam. The plasma-like brilliance of a single-source light creates lens and reflector challenges that each light manufacturer has to deal with.

Because of this challenge, you have to be careful about simply swapping out bulbs and using your current lens housing. Although this can significantly reduce the cost of changing from incandescent to LED, it is important to match the bulb with the housing for which it is designed. Otherwise, your new masthead light and bulb might not have the brightness or color that you need, and is required by international rules. In fact, the approval process for running lights require that a running light be tested in its designated lens, so although a mismatched bulb-housing combination might meet the color and output of the incandescent light it is replacing, it might technically be out of compliance. Even if you decide that saving money is worth the risk of non-compliance with international and federal code, you should at least do a carefull visual comparison of the new and old light combinations.

When it comes to navigation lights aboard sailboats, brighter is definitely better. And our tests of LED nav lights proved that more light can indeed be made with less energy.


Rule 25 of the U.S. Coast Guard's rules state that a sailing vessel shall exhibit sidelights and a stern light. Boats shorter than 65 feet may have these combined in one fixture (a tri-color masthead light). To comply with accepted standards, the lights must meet the following visibility minimums:

  • Sidelight: 2 miles for boats over 36 feet; 1 mile for boats under 36 feet

  • Sternlight: 2 miles

  • Towing light: 2 miles

  • All-round light: 2 miles


Comments (6)


I believe that the visibility in ocean swells trumps any other consideration, but local visibility at deck level is also important. Hence my preference for the all-around red over green at mast head, and the normal deck lights at deck height.

With today's LEDs, consideration of the extra power draw of additional lights is not needed.


Posted by: PAUL J | January 21, 2014 7:27 PM    Report this comment

A steaming light cannot be shown with a tricolor when under power. The rules are very clear that the steaming light must be at least 1 meter above any deck lights (hence most power boats have a small mast which the steaming lights sits on).

The tricolor is only applicable to sailing vessels under sail alone, not power.

The best way to think about it is to say that if your sailing boat has an engine, then it is really two different boats for lights: 1) a sailing boat, and 2) a power boat. You need to have the lights for both of these types of craft. The tricolor is purely a sailing boat light.

Posted by: PAUL J | January 21, 2014 7:24 PM    Report this comment

Advantages of tricolor include better visibility in ocean swells, when pulpit lights may not be continuously visible, fewer bulbs and connections to maintain, lower energy consumption.

Advantage of pulpit mount is that it is easier to service.

Posted by: Darrell | January 19, 2014 9:38 PM    Report this comment

Can you run a Steaming Light as the same time as a Tri Colour Masthead light and be in compliance with the Collision Regulations?

Posted by: Ann H | January 18, 2014 8:40 PM    Report this comment

Does the LED version of the Series 40 Tricolor fit into the same base as the incadesent model? TX

Posted by: Jack M | January 15, 2014 1:54 PM    Report this comment

what is the advantage to a tri-color masthead light vs all-around white masthead/ pulpit mounted running lights?

Posted by: Patrick G | January 15, 2014 1:39 PM    Report this comment

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