Lumishore SMX21 The Bright: Available in blue, white or green, the Lumishore SMX21 puts out light equal to that of higher-priced models. It draws 1.2 amps at 12 volts to produce 1,300 lumens and can be used either above or below the waterline. The lens is a tough borosilicate, and it resists the growth of fouling organisms. Surface mounted, it requires a single small cable hole to install.
The Dim: This is the most expensive of the three LED lights compared, offered at $299 retail and selling for $289 at West Marine.
Attwood LED Underwater Lights The Bright: The only noncircular model of our three lights, Attwood’s lights draw less than 1 amp while producing a high-output light. I installed these on my old boat and it was easy. Drill a small hole for the wiring, apply appropriate sealant, and then use two screws to secure the light to the hull. It measures 5.7 inches long by 1.7 inches wide by 0.7 inches high.
The Dim: Reviews at West Marine have complained of corrosion issues on the housing and with the individual LEDs.
Aqua Signal LED Underwater Multipurpose Light, Silver/White The Bright: The least expensive of our trio is priced at $249.99. Colored versions cost up to $279.99. They’re the only ones claimed to also be used as a deck light. They are surface-mount with a 4-inch diameter and come with a watertight 5-foot-long cable. The housing is anodized aluminum and the light draws 550 milliamps.
The Dim: At five-eighths inch tall, it is the thickest of the three, which installers should keep in mind for fitting on their boat.