Ancor Dark Blue 18 AWG Tinned Copper Wire - 35'

Ancor has been building marine-grade wire for boaters for decades, and this dark blue 18 AWG tinned copper primary wire is a good example of why their stuff holds up out on the water. It's a 35-foot length of single-conductor primary wire in 18 gauge, sized for low-current DC circuits. Think nav lights, instrument panel feeds, gauge and switch backlighting, small accessory runs, and the dozens of little wiring jobs that add up on any rigged boat. The dark blue color helps keep your wiring diagram straight, and plenty of folks use it for negative returns on smaller sailboats.

Ancor got started to solve the exact electrical headaches boaters run into offshore. General-purpose wire built for cars and houses just doesn't hold up once salt air, moisture, and vibration get at it, and as boat electrical systems got more sophisticated those shortcuts started causing real problems. This wire is the answer to that. It's built from the ground up to live on a boat, not to be adapted from something meant for the driveway.

The big difference between this and the cheap spool at the auto parts store is the tinning. Every copper strand is coated in tin, which fights the corrosion and electrolysis that eat bare copper alive in salt air. Ancor uses Type 3 stranding, the finest and most flexible stranding class, so the wire bends easily around tight console corners and stands up to the constant vibration and flex a boat puts on it. Bare copper goes green and brittle. Tinned copper keeps carrying current season after season.

The insulation is premium vinyl rated at 600 volts, 105 degrees C dry and 75 degrees C wet. It stays flexible all the way down to -40, so it won't crack when you're rigging in the cold, and it resists salt water, battery acid, oil, gasoline, heat, abrasion, and UV. That matters when a run passes near a battery bank or through a locker that sees fuel and sun. The whole product exceeds UL 1426, ABYC, and US Coast Guard Charter boat standards (CFR Title 46), so it's the right wire for a boat that has to pass survey.

18 AWG is on the smaller side, so match it to the load. It's ideal for LED nav lights, courtesy lighting, instrument backlighting, and low-draw electronics. For longer runs, keep an eye on voltage drop. Over about 20 feet, an 18-gauge run to something like an LED nav light can start to lose voltage, and for a main feed you'll want to step up to a heavier gauge. Always check an ABYC ampacity and voltage-drop table before you commit to a gauge on a critical circuit. Bilge pumps and higher-amp gear generally want something heavier than 18.

A few install notes from the field. When you strip 18-gauge tinned wire, set your stripper carefully, because the fine strands nick and break if the blade is set too deep. A ratcheting stripper makes this a lot easier. Tinned strands can also slip in some crimp connectors, so pair this wire with tinned marine crimp terminals and adhesive-lined heat shrink for a connection that actually holds and stays sealed. And route it away from exhaust and engine heat. The vinyl jacket lasts for years, but constant high heat right against an exhaust elbow will shorten its life, so give it some distance.

The nominal outside diameter is 7/64 inch, about 3 mm, so it pulls easily through existing conduit and wire looms without hogging space. The 35-foot length is a handy size for repairs and small projects, and you'll usually have some left over for the next job. Whether you're chasing down a dead nav light, adding a switch at the helm, or rewiring a small circuit the right way, this is the wire to do it with. Buy it once, do it in tinned copper, and you won't be back here fixing the same corroded connection in two seasons.