Defining the proposed purpose of boat lights fixtures is an important consideration and not an easy one. They may be required for general cabin illumination, or for bunk reading, or perhaps work surface illumination in the galley, or for illuminating the engine spaces. Each boat location has entirely differing requirements. Lights are more than just the average boat parts, they are essential safety equipment. If you can’t see properly on that dark and stormy night then holding a flash light isn’t going to cut it. I also never buy cheap Chinese lighting fittings, you always pay twice so best buy quality US and European fittings at the outset and save some pain later.
The incandescent fixture with its filament bulb is power hungry for the given output and they suffer from physical degradation due to vibration, and with the life being shortened in over-voltage conditions with fast charge devices. They are thankfully on the way out and you will still see them on boat supply shops gathering dust, cheap they are but you pay a heavy price in power consumption and reliability.
The fluorescent boat light fixture has a much higher lumen output over the incandescent for significantly less power consumption. Like all fixtures they have drawbacks. The most notable is that most cheaper fittings are badly suppressed against RFI interference, with often serious consequences for radio communications such as noise. The cheaper boat light fittings seen on so many boat chandlers shelves also have similarly cheap inverter electronics, with a subsequently higher rate of failure, and a much higher tube failure rate as well.
The low energy fitting is relatively new, however low energy fluorescent tube types are to be seen everywhere ashore and increasingly afloat these days. These have a very high lumen output for the power consumption. Typically a 75 watt bulb output for around 1.2 amps on 12 volt DC fittings. Most of the DC boat light fixtures being made are tolerant to over voltage with quite high quality inverters, and like all European made equipment these days, they have suppression against RFI. The tubes are not cheap and are on a par with halogens.
The halogen or HQL type has advantages that they are simple, and have high light outputs for the power consumed, with the average light having a 10 watt bulb. There are a few disadvantages, the main ones being that if you inadvertently touch a bulb, the life of it will reduce considerably as the contaminants off a finger such as sweat etc degrade the high quality glass. The bulb itself is subject to quite high temperatures. The cost of the halogen bulbs are rather expensive, typically around $8-$10. Additionally bulb life shortens considerably in over-voltage situations, typically this occurs when electrical system voltage rises to 14.6 – 15 volts under-charging or engine run situations. They do have the advantage of being dimmable which significantly lengthens bulb life, and this is recommended, also unlike fluorescent lights, you do not have an inverter to fail.
The new generation LED boat lights are now almost the standard and have very good output levels, do not generate heat and what is very important to many boaters is they do not use much electrical power. More at fishing and boats.