The right spare bulb turns a dark passage back into a lit one. This collection covers replacement bulbs for every light on board: navigation light bulbs in the correct wattages, festoon, bayonet (BA15/BA9) and wedge fittings for cabin and courtesy lights, instrument bulbs, and LED replacements that slash power draw in 12V and 24V systems.
Two things matter when replacing a bulb: the fitting (measure or match the base type) and, for navigation lights, the wattage - nav light certification depends on the specified bulb, so replace like for like. LED upgrades are excellent for cabin lighting, cutting consumption by around 90%, but for navigation lights choose purpose-certified LED fittings rather than dropping LED bulbs into filament housings. Keep a labelled box of spares aboard; bulbs always fail at night.
Frequently asked questions
Can I put an LED bulb in my navigation light?
It's not recommended - navigation lights are certified as a complete unit with a specified filament bulb, and an LED insert can change the visibility range and light pattern. For LED nav lights, fit a certified LED fixture.
What are the common bulb fittings on boats?
Festoon (tube with pointed ends), bayonet BA15d/BA15s and BA9s, and wedge W5W fittings cover most cabin, courtesy and navigation lights - match the base type and voltage when replacing.
Are LED bulbs worth it for cabin lights?
Yes - LED replacements draw around a tenth of the power of filament bulbs, run cooler and last far longer, which makes a real difference to battery life at anchor.
