Swapping halogen bulbs for LED equivalents looks like the simplest upgrade on a boat, and for interior cabin lighting it usually is, but a full LED upgrade touches current draw, dimming compatibility, radio interference and, for navigation lights, compliance with COLREGs specifications. Getting it right reduces load on the battery bank noticeably; getting it wrong introduces flicker, interference with VHF and AIS, or navigation lights that no longer meet the required visibility range.
This guide covers what actually changes when you move a boat's lighting to LED, beyond the obvious point that it uses less power.
A typical 10W halogen festoon bulb draws close to 0.8A at 12V; an equivalent LED replacement often draws under 0.15A for comparable light output. Across a boat with a dozen or more interior lights run for several hours each evening at anchor, that difference is genuinely significant to the daily amp-hour budget, often more effective at extending time off shore power than adding a modest amount of solar.
This is one of the few boat upgrades where the payback is straightforward to calculate: multiply the number of fittings, the current difference, and typical hours of use, and compare that daily amp-hour saving against your house bank capacity.
Many older boats dim interior lighting with a simple resistive or rheostat-style dimmer designed for the higher current draw of halogen bulbs. LED drivers do not dim the same way, and a mismatch commonly produces flicker, a limited dimming range, or lights that will not dim below a certain level at all.
PWM-based LED dimmers, or fittings with dimming built into the LED driver itself, generally give smoother results than trying to reuse an old resistive dimmer switch, and this is worth checking before ordering fittings for a saloon or cabin where dimmed lighting matters.
LED fittings are sold across a range of colour temperatures, from warm white around 2700-3000K, close to old halogen, through to cool white above 5000K, closer to daylight. Warm white generally suits saloons and cabins where the old halogen look is wanted; cool white suits chart tables, galleys and work areas where clarity matters more than ambience.
Mixing colour temperatures inconsistently across a boat looks worse than either choice on its own, so it is worth deciding a scheme before buying fittings piecemeal.
Cheap, unfiltered LED drivers are a known source of radio frequency interference that can raise the noise floor on VHF and AIS receivers, sometimes badly enough to mask weak signals. This is one of the most common issues we see after DIY LED conversions, and it is not always obvious until the boat is out on the water trying to receive a weak AIS target or a distant VHF call.
Navigation lights are governed by COLREGs requirements for colour, arc of visibility and minimum range, which for most leisure craft translates into a minimum luminous intensity the fitting must achieve, not just a subjective brightness. LED navigation light replacements should be sold and fitted as compliant navigation lights, not adapted from generic LED fittings, and should carry the appropriate certification.
An LED anchor or navigation light that looks bright close up can still fail to meet the required visibility range at distance if it is the wrong specification, which matters in a genuine collision-avoidance situation.
You can, and it is a fine approach for interior lighting, though you may end up with mixed colour temperatures for a while. For navigation lights, replace with a properly certified unit rather than a generic bulb swap.
It can, usually from an incompatible dimmer or a cheap driver reacting to voltage variation as the alternator or charger cycles. Marine-rated fittings with good drivers are far less prone to this.
Yes, for compliance they need to meet the relevant COLREGs visibility and arc requirements, and should carry appropriate certification rather than being a generic LED bulb fitted into an old housing.
The battery saving matters less, but LEDs still run cooler, last longer, and are more resistant to vibration than filament bulbs, so there is still a case for it.
Poor quality or unfiltered drivers can raise the noise floor and mask weak signals. Marine-rated fittings with proper EMC filtering largely avoid this.
We specify and fit marine-rated LED lighting, including compliant navigation lights, and check for interference before calling the job finished.