How to Replace Marine Speakers (Including Tower Speakers)

With power off, remove the grille and screws and ease the speaker out. Before disconnecting, photograph or label which wire goes to + and which to –. Look at the old terminals and wire ends: green corrosion or brittle wire means you should cut back to clean copper or replace the run.

Look for chafe where the wire passes through panels, and fit rubber grommets in any bare hole. Garmin recommends 16 AWG oxygen-free copper speaker wire for typical runs, heavier wire for long ones, and warns against copper-clad aluminum. Tinned marine wire resists corrosion best. If the old wire is undersized, corroded or spliced, run new wire (see our chase tube guide).

BoatUS advises mounting speakers up high, near ear level and forward of the helm; speakers aft of the helm get their sound blown away by the wind underway. Before cutting, make sure you can actually route a wire there. For exposed spots, Garmin says to mount on a vertical surface: a speaker facing straight up collects water and gets damaged over time. Keep speakers well above the waterline and away from where docks and pilings can hit them.

Boating Magazine's installation guide (based on advice from a major speaker maker) adds a few placement rules: mount each pair opposite each other, facing the centerline, as far apart as you can; aim them toward where people's ears will be; skip deck-level spots where feet hit them and transom splashwells that get soaked; and avoid curved or upholstered surfaces, where the gasket can't seal. Speakers in a pair don't have to be the same size: a larger pair aft and a smaller pair in the bow is fine. New marine speakers are often deeper than old ones, so measure behind each spot first.

Hold a handheld compass (or watch the boat's compass) while you bring the new speaker toward its planned spot. If the needle moves, you're too close. Choose a spot beyond the speaker's listed compass-safe distance, or pick a different location.

If the new speaker matches the old hole, test-fit it. If it doesn't:

• A slightly smaller speaker can use an adapter ring.
• To enlarge a hole, tape the panel, trace the template, drill a starter hole and cut with a jigsaw or hole saw running at high speed to avoid chipping gelcoat. Check behind the panel first. Don't force a speaker into a tight hole; it can crack the frame or the panel. Boating also suggests beveling the edges of each screw hole slightly so the gelcoat doesn't crack when the screws go in.

Speakers with LED lights need their own 12-volt feed, separate from the audio wires. Boating's example wires the lights through a small inline fuse and an on/off switch; use the fuse size and wiring in the speaker's instructions (some change color depending on how the power leads are connected).

Garmin's instructions are blunt: the front of a marine speaker is water-resistant, but the rear, its wires and connections are not, and moisture getting to the rear can make the speaker fail and even catch fire. Mount it where spray and washdown water can't reach the back, and don't mount it in an enclosure with a vent open to the weather. Make sure water that does get behind the panel can drain away.

Crimp heat-shrink connectors (or the speaker's supplied connectors) onto the wire ends, then shrink them. Avoid twist-and-tape joints and bare wire pushed under a terminal. Keep each terminal from touching metal or the other terminal; Garmin warns that grounded or touching speaker terminals can damage the stereo.

Connect the stereo's + speaker wire to the speaker's + terminal (usually marked, often wider or red) and – to –, the same way on every speaker. If one speaker is reversed, the speakers work against each other and the bass sounds thin. Most speaker wire has a stripe or ridge on one conductor; use it consistently.

Use the gasket that comes with the speaker. If there is none, BoatUS suggests a bead of sealant around the edge; follow the speaker maker's instructions on what to use. Start the screws by hand or with a driver on low, and finish by hand. Garmin warns that fully tightening with a power tool can crack the speaker and void the warranty. Snug is enough.

Wakeboard-tower and roll-bar speakers are larger, usually need an amplifier, and hang where wind and wake slam them:

• Use the clamps made for your tower's tube diameter, and check them and the tower fasteners regularly (see our tower hardware guide).
• Run wires through the tower tube or along it with UV-resistant ties, with a drip loop before each speaker so water runs off instead of into the connection.
• Aim them a little down and toward the listening area, and fold-down towers need enough wire slack to fold without pulling the connections. BoatUS notes that bigger systems with tower speakers may also need more battery capacity so the stereo doesn't drain the starting battery.

Restore power, set the volume low, and use the stereo's balance and fader to check each speaker plays on its own. Then play music with plenty of bass: if it sounds thin with all speakers on but fuller with one off, a speaker is wired backward. Recheck the compass with the stereo playing.

Put covers on if your speakers came with them, rinse salt spray off grilles with fresh water, and keep the boat covered when possible; sun is what kills cones and grilles. Note the speaker model and install date in BoatMend.