If you’ve ever stood on a catamaran at sunset, watching the sky bleed pink over the water while your bow light cuts a clean, steady path through the waves, you know marine lighting isn’t just a cosmetic upgrade—it’s non-negotiable. But when I get calls from catamaran owners, I hear the same confused frustrations over and over: “There are a hundred different lights online. How do I pick ones that work on my twin-hull boat?” As a marine lighting supplier who’s worked with everything from 32ft day sailors to 70ft bluewater cruisers over the last 12 years, I don’t just sell bulbs and fixtures—I help people avoid the mistakes that get them flagged in a port state control (PSC) inspection, or worse, leave them adrift after dark in rough seas. Marine Lighting
First, let’s talk about what makes a catamaran different from a monohull, because that’s the root of most bad choices. Monohulls tilt, their lights stay relatively aligned with the horizon, and they don’t have the wide, stable platform that a catamarans has. Catamarans sit flat—no heeling, even in 20-knot winds—and their hulls sit side by side, so the space for mounting lights, running wiring, and dissipating heat is totally different. I once had a catamaran owner come to me with a set of generic monohull bow lights he’d bought online; he tried to mount them on his forward crossbeam, and because monohull lights are calibrated for a tilted vessel, they cast light down into the water when he was flat, making it impossible to see obstacles off the bow. That’s not a small issue—when you’re navigating in a shipping lane, you need other boats to see your light, not just see a blip on their AIS.
Now, let’s break down the non-negotiables, starting with compliance. I don’t care how cool a light looks if it doesn’t meet USCG, RINA, or SOLAS standards—get flagged in a PSC inspection, and you’re stuck in a foreign port for days, paying thousands in dock fees. For recreational catamarans under 65.6ft (20m), here’s the rule set: you need a masthead light (white, visible 2 nautical miles (nm) off the bow, 225 degrees each side from dead ahead), sidelights (port red, starboard green, same 2nm visibility, spanning from dead ahead to 225 degrees aft of each beam), a stern light (white, 2nm visibility, covering 135 degrees around the stern), and an all-around white light if you’re anchoring at night. For commercial catamarans—like charter boats or water taxis—you’ll need additional deck lights and loading lights, but 90% of the calls I get are from recreational owners, so let’s stick to that.
Wait, but there’s a catamaran-specific compliance quirk: because you have two hulls, the masthead light needs to be mounted at least 3.3ft (1m) higher than the sidelights, and the horizontal distance between port and starboard sidelights has to be at least 3.3ft too. That’s why generic monohull sidelights often fail—they’re mounted too close together or too low. Last year, a client with a 40ft cat came in; he’d mounted generic monohull sidelights on the forward part of each hull, 1.5ft apart, and a local marine surveyor failed him because the spacing was less than required. It’s a tiny detail, but it’s the difference between a safe passage and a fine.
Next, brightness and energy efficiency—two metrics that are more intertwined for catamarans than for monohulls. Catamarans have larger battery banks than most monohulls, but they also rely on solar panels and wind generators to power everything, so wasting power on inefficient lights is a no-go. Here’s a real stat I pull up for every client: a traditional incandescent navigation light uses around 10 watts, while an LED equivalent uses 1.5 watts—so that’s 85% less power, which means your fridge, anchor windlass, and water pump don’t have to compete for battery power at night. But brightness isn’t just about watts—it’s about lumens, and beam angle. For a masthead light, you want a 120-degree beam angle, so it covers the full 225-degree arc without spilling light where it’s not needed (spilled light is wasted light, and it can also blind other boaters or create glare for your own crew). For sidelights, you want a narrow 90-degree beam, focused exactly where other boats are looking—dead ahead and off the beams—so you don’t have light leaking behind the hull, which would make your boat look smaller than it is (a deadly mistake in heavy traffic).
But here’s a myth I hear all the time: “More lumens = better.” No. The USCG requires a minimum lumen output, but exceeding that wastes power and can create glare. A few years back, I had a client who installed 5,000-lumen masthead lights (the minimum is 1,000) on his 50ft cat; he complained his battery bank died in 8 hours overnight, when it should have lasted 48. The extra lumens were just being shot into the sky and the water—wasted. So stick to the minimum required lumens for your vessel length, and only upgrade if you’re sailing in areas with lots of commercial shipping.
Then there’s durability, which is non-negotiable for any marine light, but especially for catamarans. Catamarans sit on the water longer than most monohulls—many owners live on them full-time, or leave them anchored for months at a time—so lights have to handle saltwater, UV exposure, temperature swings, and the occasional bump from dock lines. When I test lights for my inventory, I run three tests: salt spray exposure (1,000 hours in a 5% salt solution, per IEC 60068-2-11), thermal shock (from -22°F to 122°F, repeated 500 times, per IEC 60068-2-14), and vibration testing (mimicking the chop of 10ft seas, per ISO 16750-3). Any light that doesn’t pass these tests goes straight back to the manufacturer. I once had a client bring in a set of cheap eBay lights that corroded through the wiring in 6 months—he’d mounted them on his starboard hull, and the salt spray had eaten through the aluminum housing. The marine grade stainless steel or high-performance polycarbonate housings I stock? They don’t corrode, and the silicone gaskets prevent water from getting inside, even when you’re pounding through waves.
Another catamaran-specific consideration: mounting and wiring. Because your crossbeams span between two hulls, running wiring from the mast to sidelights on opposite hulls requires longer runs, and those runs have to be protected from chafe. I always recommend using tinned copper marine-grade wiring—copper corrodes when exposed to saltwater, and tinning prevents that. Also, for masthead lights on catamarans, don’t mount them on the forward crossbeam. I know it’s tempting—it’s a flat, easy spot—but most crossbeams aren’t strong enough to support a heavy light, and the vibration from wind there will break the bulb or damage the LED driver over time. The best spot for a masthead light is at the very top of the main mast, 3.3ft above the highest point on the crossbeam.
Now, let’s talk about specialty lights for catamarans, because navigation lights aren’t the only ones you’ll need. Anchor lights: for catamarans, an all-around anchor light mounted on the mast is better than separate lights on each hull, because it creates a single, uniform bright light that’s easy for other boats to spot. I once had a client who mounted separate anchor lights on each hull, and a sailboat ran into him at night because the two lights looked like two small fishing boats, not a single catamaran. Deck lights: if you’re doing evening cooking, tending to a tender, or moving supplies around after dark, you want LED deck lights with a warm white color temperature (2700K to 3000K). Cool white (5000K and above) is harsh, and it ruins your night vision, making it hard to spot buoys or other boats. I always tell clients: if you can’t see something 10ft in front of your deck light, it’s not bright enough, but if it’s blinding, it’s too bright.
Wait, and what about underwater lights? That’s a big one for catamarans, especially for people who sail in the Caribbean or Mediterranean. Underwater lights aren’t required by compliance rules, but they add safety (you can see if a mooring line is tangled in the hull) and a huge amount of fun. But for catamarans, you want lights that are mounted on the inside of the hull, not the outside, because mounting them on the outside means drilling through the hull, which can create a leak. Also, catamarans sit deeper in the water forward than aft, so you want to mount underwater lights at the midpoint of each hull, not too far forward or too far back. I recommend RGBW underwater lights for catamarans—they let you choose a color for ambiance, and white for night visibility, and they use even less power than navigation lights. The only catch? Make sure the light has an IP68 rating, which means it’s completely dust-tight and can be submerged in water up to 10ft deep indefinitely. Most cheap underwater lights are only IP67, which means they’re water-resistant, not waterproof—they’ll fail after a few months in saltwater.
Now, let’s cover the mistakes I see over and over, so you can avoid them. First, buying generic monohull lights for a catamaran. As I mentioned earlier, the mounting spacing and calibration are wrong. Second, skimping on power efficiency. Catamarans have larger battery banks, but they still rely on limited renewable power, so wasting 10 watts per light adds up over a season. Third, ignoring durability. A light that costs $20 will need to be replaced twice a year—total cost $400 over 5 years. A light that costs $800 will last 10 years—total cost $800, which is cheaper in the long run. Fourth, not checking compliance rules. Different countries have different rules—for example, in some European countries, masthead lights need to be visible 3nm, not 2nm. I always send clients a quick cheat sheet for the countries they plan to sail in, because one size doesn’t fit all.
If you’re feeling overwhelmed, you’re not alone. I’ve spent years perfecting a process that helps catamaran owners pick the right lights without spending a fortune, or wasting hours researching. We start with three quick questions: what size is your catamaran, where do you sail, and what’s your budget? Then we narrow down the options to lights that meet your specific needs, not just the ones that are the most expensive or the most popular. I don’t push products that don’t fit a client’s boat—last month, I turned away a client with a 32ft day sailer who wanted commercial-grade lights, because they were overkill and would have wasted his battery power.
When you’re shopping for marine lighting for your catamaran, don’t just look for “marine-rated” on a label. Look for the test standards, the compliance certifications, and ask for references from other catamaran owners. At the end of the day, your lights are what keep you safe after dark, when the water is dark and the only thing you have to go on is what you can see. If you’re ready to upgrade your navigation lights, add deck or underwater lights, or just have questions about what will work best for your catamaran, we’re here to help. Our team has been working with catamarans for years, and we know the ins and outs that generic suppliers don’t. We don’t just sell lights—we give you the advice you need to sail safely, confidently, and legally.
Emergency Lighting Fixtures References:
ISO 16750-3: Road vehicles – Environmental conditions and testing for electrical and electronic equipment – Part 3: Mechanical loads
IEC 60068-2-11: Environmental testing – Part 2-11: Tests – Test Ka: Salt mist
IEC 60068-2-14: Environmental testing – Part 2-14: Tests – Test Nb: Change of temperature
United States Coast Guard Navigation Rules, Inland and International
RINA Rules for the Construction and Classification of Pleasure Yachts, 2022
Jiangsu Guoxing Electric Equipment Co., Ltd.
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