How To Install Flush-Mount Marine Speakers

Properly installed marine speakers help optimize onboard sound quality
Installing Flush-Mount Marine Speakers
Installing Flush-Mount Marine Speakers Tim Barker

Installing basic flush-mount stereo speakers on a boat is relatively easy, but there are a few tricks that help to optimize the sound quality and ensure the longest possible life of the speakers. First and foremost, buy marine speakers. Brands such as Boss, Clarion, Fusion, JBL, JL Audio, Jensen, Kicker and Polk offer special flush-mount, coaxial speakers designed for the wet, corrosive environment of a boat, with features that include waterproof cones, sealed magnets, mounting gaskets, stainless-steel hardware and UV- and rust-resistant covers.

With the exception of a subwoofer, most marine speakers come in pairs, and most deck boats and runabouts have room for one to three pairs of speakers. Most stereo units have speaker outputs for as many as three to four pairs. Additional speakers and a subwoofer might require a separate amplifier. Here are the key steps to install flush-mount, coaxial speakers based on guidance provided by ASA Electronics, which includes the JBL, Jenson and Polk brands.

Quick Tip: If installing marine speakers in a relatively thin aluminum or fiberglass substrate, through-bolt it with nylon-locking nuts and backing washers to prevent the speaker from vibrating loose. Also, use masking tape in the area to be cut and drilled to prevent the gelcoat from cracking. When a flat area cannot be found, caulking the speaker, once installed, may be necessary.


Getting Started
Skill Level: 2/5
Time to Complete: 5 Hours

Tools and Supplies
* Polk Audio DB651 6½-inch, 180-watt coaxial marine speakers ($111.99/pair;
* Marine-grade speaker wire (length depends on the boat size and the number of speakers)
* Crimp-on female spade terminals
* Diagonal cutters
* Wire strippers
* Crimping tool
* Power drill with ½-inch chuck (needed for hole saw) and bits
* 5-inch hole saw
* Screwdriver set
* Electricians snake (for running wires and cables)
* Spool of cord (for pulling wires and cables)
* Wire looms and zip ties

Installing Flush-Mount Marine Speakers
Layout the System Tim Barker

1. Layout the System
Decide how many speakers and where to mount them. For the best sound quality, each pair should be ­opposite each other and face the centerline with as much distance as possible between the two. Most deck boats and runabouts have room for one to three pairs of speakers, often along the inwales or seat bases. Where possible, point speakers toward the listeners’ ears for the best audio possible. Now is also a good time to run speaker wires from the stereo unit to each spot, securing the wires along their entire runs.

Installing Flush-Mount Marine Speakers
Areas to Avoid Tim Barker

2. Areas to Avoid
Don’t mount speakers where they are easily kicked and damaged (e.g., at deck level) or bathed in spray (e.g., by a transom splashwell). Stay clear of curved and upholstered surfaces. Locate each speaker a safe distance from sensitive equipment (as detailed in your installation manual), such as a compass. The speaker magnet can cause interference. If the back of the speaker is located in a storage area, ensure that the speaker wiring is protected from snagging. Wire looms and zip ties are good supplies to have on hand for this reason.

Installing Flush-Mount Marine Speakers
Choose Your Speakers Tim Barker

3. Choose Your Speakers
Measure each location, then choose speakers based on available space. Today’s marine speakers tend to be deeper than in the past, reflecting larger magnets and more robust construction. Speakers need not match in size. For instance, you might be able fit a pair of 6½-inch-diameter speakers in the aft cockpit, but only 5¼-inch-diameter speakers in the bow area. Aesthetics dictate using the same brand and grill design for each. In this example, we chose Polk Audio 6½-inch, 180-watt coaxial round marine speakers.

Installing Flush-Mount Marine Speakers
Install Each Speaker Tim Barker

4. Install Each Speaker
Trim and attach the template to the mounting surface. Use a 5-inch hole saw to cut the main hole. (Oval speakers will require a saber saw to cut the oblong hole.) Then drill each of the mounting holes. Bevel each hole to keep the gelcoat from cracking. Place the foam gasket on the back of the speaker, aligning it with the mounting holes, and attach the speaker wires to the spade fittings in the speaker, making sure the polarity is correct. Slide the speaker into the main hole and secure it with the mounting screws.

Installing Flush-Mount Marine Speakers
Speaker Sparkle Tim Barker

Speaker Sparkle
A number of marine speakers today feature LED illumination. Fusion’s Signature Series speakers, for example, offer either a blue or white glow, depending on how you wire 12-volt power to each speaker. Wired conventionally (red to positive, black to negative), illumination is blue; reverse the polarity for white. Install a 3-amp fuse to protect the circuit and a switch in the power line to turn the LED on or off.