I'm a big fan of LED lights and they are now so sophisticated that I can't really fathom why anyone would want to continue to use regular bulbs of any sort aboard. LED's use about a fifth of the power of regular incandescent bulbs yet produce as much light. Regular light bulbs are very good at producing heat which accounts for something like 90% of the energy consumed while light is almost a by product. That heat can degrade head linings and the extra heat can be a real bear especially in the warmer weather which may require running the A/C unit to suck it out of the cabin.
Some time back I upgraded the lights on Mallard my Golant gaffer from incandescent to LED lights. At that time I used the Hatteras lights from Imtra which made a vast difference to the interior of the boat. Not only was I able to install a total of five lights which consumed less electricity that the two previously installed but the light output was constantly variable from off to wow. As I was installing the lights essentially from the word go I ran new cables to each of the fittings; four wires were required, two for the power and a second two for the dimming circuit making four in all. Of course in my installation where the cables were essentially surface mounted the extra couple of wires was not an issue but what if the wires are hidden behind a headliner, furniture or other obstacle as might well be the case in an older boat. Thankfully Imtra have addressed that and introduced the Sigma light. About the size of a small hockey puck the light can either be surface mounted or set flush into the over head panel. The best part about the light however is that it is compatible with many halogen digital dimmers and as such can be used with just two wires making retrofitting a very easy job. The light operates on any voltage from 12 to 40 volts DC and although not cheap with a starting price of $160 it is a quality product. Available in both warm and cool white color temperatures the lights have a useful lifespan of 50'000 hours so conceivably would outlast the average boat by a factor of 20.
The Sigma series is available in small, large and surface-mounted configurations. Sigma Small, with a 2-9/16” (65mm) cut-out, is sized to be a drop-in replacement for many of the popular 20 Watt halogen recessed spots that have been used in the industry for years. Sigma Large contains the same light engine as Sigma Small and is supplied with a larger diameter trim ring and special adapter plate that allows its placement in hole cut-outs from 2-9/16” (65mm) through 3-7/16” (87mm). Sigma Surface Mount is designed for surface-mount installations and is ideally suited for under cabinets or ceilings with restricted recess depth. The fixtures can be installed with included springs or screw-mounted.