We tested, reviewed and recommended a variety of marine audio products to our readers. To round up the knowledge, we thought of sharing our analysis and learning to build a marine audio system. It is a task that requires some know-how of audio equipment and marine conditions. We will first take a look at the components that make up a marine stereo system and then discuss how to assemble them. We will also talk about the salient features of marine sound equipment and the factors to consider while buying them to ensure that your system stands the test of time. Let’s begin.

Marine Audio System – A Complete Know How :

When you talk about a boat sound system, the first thing that comes to mind is the durability of the system. It must able to withstand harsh sea conditions like sunlight, lashing waves, rain, fog, salt, wind and dust. It must be resistant to corrosion, impact and UV radiation. For this, understanding the Ingress Protection (IP) rating of the device is important.

IP Rating :

The IP rating of a gadget indicates the extent to which it is protected against microscopic solid particles and water. The rating is denoted by the letter ‘IP’ followed by two digits. The first digit indicates the level of protection against solid objects and the second digit indicates the level of protection against water entry. For instance, a speaker with an IP rating of IP67 means it is completely protected against dust and can be temporarily immersed in 1-meter-deep water for up to 30 minutes. The following chart shows the various levels of protection.

Key Attributes of Marine Sound Equipment :

Water-resistant :

Marine audio devices are resistant to water. They have hydrophobic polypropylene coatings, rubber gaskets and tightly sealed Teflon-treated cabinets to prevent damage due to water and moisture.

Waterproof :

Waterproof means completely submersible in water. The duration and depth of immersion may vary from product to product. Waterproof devices are more expensive than water-resistant devices.

UV-resistant :

Marine-grade audio equipment is protected against ultra-violet radiation from the sun. The housings of speaker and receivers are specially treated with UV-resistant chemicals to prevent sun-damage.

Anti-corrosion :

Marine gadgets are protected against corrosion from wind, water, salt and mud. They have rust-free chassis, plated connection ports and pure stainless steel metal parts. Sensitive components like circuit boards and processors are sprayed with a superhydrophobic coating which has anti-corrosive and anti-icing properties. It is called conformal coating and it typically involves a coat of epoxy or urethane.

Dustproof & Mudproof :

Most marine sound devices are fortified against dust, mud, sand and similar solid foreign bodies. They have rugged and sealed enclosures that prevent these particles from entering.

Shockproof :

Shockproof marine gadgets can take a knock or two. They are solidly built and absorb impact without suffering any damage.

If you want your system to work smoothly and last longer, make sure the individual components have these properties, which brings us to our next segment, the components.

Components Of A Marine Audio System :

Receiver :

For your boat audio system, you will first need a weatherproof marine receiver with a water-resistant cabinet and faceplate. The circuit board must be conformal-coated. The input and output connectors must be plated. The remote control must also be water-resistant. In short, find a receiver that has all its parts insulated against moisture, salt, UV-rays and chemicals.

Speakers :

The next thing you will need is speakers. Opt for speakers with mylar or plastic (polypropylene) cones. They are better suited for life on the high seas than those with paper cones. Make sure the cones have rubber surrounds as rubber makes the speaker more water-tight. The outer enclosure including the grilles and the mounting hardware must be UV-protected and corrosion-resistant.

Subwoofer :

If you love bass, you might want to add an external marine subwoofer. Select a sub with plastic cones and rubber surrounds to steer clear of water-damage. Boats can be challenging when it comes to installing stereo systems. So it might be a good idea to invest in a subwoofer that is designed for all kinds of mounting applications like ported, sealed and free-air applications.

Amplifier :

If you have high-power speakers and/or a subwoofer, a simple stereo head-unit might not be enough to drive the loudspeakers. You might need an amplifier to provide the necessary power. Our suggestion would be to go for a water and impact-resistant amplifier with conformal-coated circuitry and plated connectors. For small and mid-sized boats, a 2-, 3- or 4-channel amp should do. For larger vessels, a 5- or 6-channel amp is perfect.

Stereo Wiring :

The wires and cables needed for setting up your system should also be marine-grade. Look for tinned wiring to make the arrangement more weatherproof.

Satellite Radio :

No boat stereo system can be complete without a SiriusXM satellite radio. It offers excellent reception up to 200 miles offshore. Most marine receivers are satellite radio-ready. They have provisions for mounting an external satellite radio tuner discretely and connecting to the radio via cable. Plug-and-play satellite radio tuners can also be transferred from your home or car audio system to your boat. To operate them you will need a marine-grade kit with a weatherproof antenna.

Power Inverter :

A power inverter is very important for your boat audio system. It can charge your smart phone, tablet, laptop and other small electronics when you are out on the water. When choosing a marine power inverter, make sure it has a Ground Fault Circuit Interrupter which is needed for protecting against electric shocks.

Factors To Consider While Selecting A Marine Stereo Receiver :

Now that we know what a marine stereo system consists of, let us move on to the factors to consider while choosing these components. In general, when it comes to building a boat audio system, there is no one perfect way of doing things. Every vessel is unique. It has its own layout, paneling and power handling capacity, and each of these factors has a direct impact on your choices. In the following section, we will talk about all the things you need to examine while buying marine audio equipment.

Size And Installation :

If you are installing a receiver for the first time, you will need to cut out a portion of the paneling and lay down new wires to connect the parts. Boats normally have a designated space on the dash for audio installations. Measure the length, breadth and depth of the space provided, and select a stereo that matches the dimensions.

If you are replacing an existing receiver, make sure the new receiver fits the cut-out of the previous one. If it doesn’t, you might have to incorporate mounting plates and adapter plates to get the perfect fit. Do not throw out the old wiring. You might still be able to use it with the new head-unit.

Marine receivers have a standard single-DIN size of 7 inches x 2 inches x 7 inches. However, these days they come in all kinds of shapes and sizes. While most receivers maintain a DIN-size chassis, they might experiment with the faceplate and make it larger so that it overlaps the mounting panel. Some stereo receivers, especially ones that play directly from iPods and smart phones, are small in size and look more like remote controls docked to the dash. They have shallow mounting depths, and may be round or rectangular in shape. Some receivers are in the form of a small box which contains the radio, the amp, and all the wiring inputs and outputs. Such receivers are controlled via remote and require very little space for installation. Some receivers have universal mounting and can be mounted to any surface. They don’t need to be installed in the dash, and have rugged water-resistant and UV-protected cabinets.

In a nutshell, whether you are building a system from scratch or upgrading an existing system, be very clear about the size of the new receiver. It must match the installation space on your boat, or you will be stuck with an ill-fitting contraption that won’t last very long.

Power Output :

The power output of a stereo is measured in peak power and RMS power. Peak power is the highest power a receiver is capable of generating at any given point of time. RMS power, also called continuous power, is the average amount of power the system can produce over a period of time. Since peak power is more than RMS power, brands sometimes deliberately omit the RMS power and only mention the peak power of a device. This is an instance where the buyer needs to exercise discretion and carefully study the power capacity of the device before going in for a purchase.

A typical 4-channel stereo receiver is capable of a peak power output of 40 to 60 watts per channel. This means you have a total peak power of 160 to 240 watts which, when translated into RMS power, gives you roughly 15 to 25 watts per channel. This is a pretty good average for small to medium-sized vessels with 2 to 4 speakers.

If you have more than 4 speakers, or if you want more power for your speakers, you might want to consider adding an external amplifier. We do not recommend powering more than one speaker from a single receiver channel. You might end up damaging both the receiver and the speaker.

Connections :

Input ports direct signals into the receiver from a media source like a smart phone while output ports send signals from the receiver to speakers and subs. If you want to connect to a variety of devices, your stereo head-unit must have the necessary connectors. First and foremost, it must have auxiliary ports for plugging in MP3 players, satellite radio, smart phones and DVD players. Most stereos have 3.5mm AUX input jacks for accepting sound input through audio cables. But you cannot use these for recharging your phone. If you want to play music, and also control and recharge your device, you need a USB jack. The jack can also be used to play songs directly from a USB flash drive. If you use SD cards, your receiver must have an SD card reader. If you want a wireless arrangement, make sure the receiver is Bluetooth-enabled. If you like streaming music on Spotify, Pandora, Apple Music, etc., check if the receiver supports these apps. Also, check compatibility for iOS and Android gadgets. Some Apple devices might have proprietary software which might not work with the head-unit’s USB port.

The outputs of the receiver are equally important. Choose a stereo that has multiple sets of preamp outputs so you are free to add on marine waterproof soundbars, speakers, amps and subwoofers as you like.

Oversized Buttons :

The buttons and knobs on your stereo must be larger than average so it is easy to control the system when the waters are too choppy. You want something you can see and push easily when the boat is unsteady. Choose a device that has the key functions laser-etched onto the rubber covers of the buttons. This will prevent the symbols from wearing off with use or sun-exposure.

Display :

The receiver should have an illuminated display screen so you can see the song titles, radio stations and other important information. Most importantly, check if you are able to read everything clearly both in the sun and in the dark.

Remote Control :

Most marine receivers come with wired or wireless remote controllers. You can also buy remotes separately. The remote can be mounted on the dash or far away from the stereo in another part of the boat. It must have a proper docking station so you don’t misplace it. For greater convenience, we recommend installing more than one remote. You can have one at the helm and another near the swim platform. Also, RF (radio frequency) remotes are more efficient than IR (infra red) remotes. You don’t need to point them at the head-unit; they can transmit signals right through walls unlike IR remotes. These days you also get app-controllable head-units. These certainly have an edge over traditional head-units as they are easier to access and control.

Satellite Radio :

Make sure your stereo has provisions for installing a satellite radio tuner. You will need a radio kit and an antenna to set it up.

Other Specifications :

The receiver must have a wide frequency response so it can process very low and very high frequency bands. It must also have a high CD signal-to-noise ratio for balanced sound. A built-in docking station is preferable. You will have a safe and dry place to store small electronic devices.

Factors To Consider While Selecting Marine Speakers :

Size And Installation :

When brands state the size of their speakers, they are normally talking about the diameter of the cone inside the speaker. The diameter of the grille and the cut-out hole may be different. A 6 ½ inch speaker, for instance, has a cone with a diameter of 6 ½ inches, but the diameters of its grille and cut-out may be higher or lower than 6 ½ inches. The grille is often larger than the cone by an inch or two while the cut-out diameter is roughly the same or less than the cone diameter. Either way, it is best to check if there’s sufficient space on the mounting surface for both the grille and the cut-out.

Flush mount speakers require greater mounting depth. So be sure the paneling has enough room for the speaker’s cone and magnet. The speaker must sit firmly in the cut-out without sticking out or rattling. Flush mount speakers also need an enclosed space behind them to optimize the resonance. If the magnet is left exposed, the music might sound thin and metallic. If you do not have any option for covering up the rear side, you can use a speaker back enclosure to create an enclosed space.

If your boat does not have a good spot for a flush mount speaker, or if you do not want to use the existing holes, you can use box speakers. Box speakers are self-contained units. They have protective weatherproof housings and can be mounted anywhere around the boat.

Location :

Another thing you need to take care of while planning your set-up is the location of the speakers. You want your speakers to be somewhere where there are no obstructions so you can hear them loud and clear. They must be easily accessible and not too far out. Tweeters, midrange and midbass speakers can be mounted to the side panels or the dash board. The sub can go under the seating area, under the bow or on a wakeboard tower. But these are just broad suggestions. Study the layout of your boat and do what works best.

Power Handling :

Your speakers must be able to handle the power generated by your receiver or amplifier. The power handling capacity of your speakers must be equal to or greater than your receiver’s or amp’s. This is the general rule when it comes to pairing speakers with receivers and amps. If, say, you have a 4-channel head-unit with a peak power output of 200 watts, it means each channel gets 50 watts. So the speakers you choose must have a power rating of 50 watts.

But peak power does not give you the full picture. You must also take into account the RMS power of the receiver and the speaker.

Speaker Type :

Once you have figured out the size and power of the speakers, you have to decide what kind of speakers you want. Following are the 4 main types of speakers used in stereo systems.

• Dual Cone

A dual cone speaker has one speaker driver and two cones. The bigger cone functions as the woofer and processes bass and midrange frequencies, while the smaller cone functions as the tweeter and processes higher frequencies. Dual cone speakers are your garden-variety speakers. They are inexpensive and have average sound quality. If you are looking for a cheaper option for your speakers, you can go for dual cone speakers.

• Coaxial

Coaxial speakers are also known as full-range speakers. They generally consist of one speaker wrapped around another in a 2-way or 3-way configuration. The way it is done is they put a tweeter, or a tweeter and a midrange speaker, in the centre of a woofer cone partially obscuring it. The tweeter, the midrange and the woofer each have their separate drivers. A passive crossover splits up the audio signal and sends the higher notes to the tweeter, the midrange bands to the midrange and the bass frequencies to the woofer. However, because the cones are mounted so close to each other, the speaker may suffer from something known as cross phase distortion. This happens when the vibrations of one cone interferes with the performance of another cone and distorts the final sound. But the good news is, it is barely perceptible. Only a trained sound expert can tell what’s happening. For the average person, it is almost indiscernible. In short, you have nothing to worry about.

Coaxial speakers have better sound than dual cone speakers. They are also more expensive. For mobile applications like a boat audio system, we highly recommend these speakers. They are better suited for outdoor conditions and are widely used in water vessels.

• Component

Component speakers are a step up from coaxial speakers. They do not have cross phase distortion as the tweeter and the woofer are completely separate. Needless to say, they have better sound than coaxial speakers and are also more expensive. Box speakers have a component configuration where the tweeter is one end and the woofer on the other.

• Subwoofer

A subwoofer is a specialized loudspeaker for bass frequencies. It is essentially an extension of a component set-up discussed above, and it serves as an additional speaker exclusively for bass. A sub however cannot work alone. It must be used together with a tweeter and a midrange to make any observable difference. To power a subwoofer, you will need a marine amplifier. The power of your receiver will likely not be enough. If your sub is not supplied with the power it needs, it will fail to generate any impact.

How To Install A Marine Receiver :

Now that we know the factors to consider while buying marine audio equipment, let us proceed to the final stage of the set-up, the installation.

If you are replacing an old receiver and the new receiver is the same brand, chances are you could use the old wiring harness. Simply plug it into the back of your receiver and you should be good. If the new receiver is a different brand, you might have to join some wires. You will have to remove the old harness and splice the new one. Don’t worry if the colors of the old and new harness don’t match. Just refer the wiring diagram in the manual and follow the instructions.

A standard marine receiver has 4 channels for connecting with 4 speakers. It has a total of 8 speaker wires, 2 for each speaker, one positive and one negative. The receiver also has wires for power. It has a black ground wire which connects to the negative terminal of the battery. It has a yellow positive power wire that connects to the positive terminal of the battery. It has a red switched power wire that connects to the boat’s ignition. Its function is to supply power to the stereo. It turns the receiver on and off as and when the boat’s ignition is turned on and off. Remember to keep this wire connected at all times. Next is a blue wire which is the control wire. If you have a powered device in your audio system like an amplifier, this wire will power it by connecting with the red switched wire. When the receiver shuts downs, the amplifier will also shut down. The blue wire is optional.

There might also be additional wires for AM/FM radio, USB port, remote control, satellite receivers, iPod plugs, etc. Since every model is different, we suggest you follow the guidelines in the manual to get the wiring right.

Once all the wires have been plugged in, you can connect them to the back of the new receiver. The rear part of the receiver is supported by a bendable metal strap behind the dashboard. You will see a bolt on the back of the chassis. Insert this into the hole on the strap and adjust the nut to get the correct position. To attach the front of the receiver to the dash, you can use screws or a mounting sleeve, whichever works best.

How To Install Marine Speakers :

If you are setting up your system for the first time, you will need to drill some holes in the paneling. If you are replacing an old speaker, make sure your new speaker fits the existing hole. If the new speaker is too large or too deep for the hole, you might have to modify the hole to make room for the speaker. If the new speaker is too small, there’s nothing much you can do except getting a different speaker that fits the old cut-out. Also, if you are upgrading, you might still be able to reuse the old wiring. So do not discard any wires without checking if they can be used.

The best way to cut out a new hole is to use a hole saw. You will get a perfectly symmetrical hole with a fairly smooth circumference. If you want to enlarge an existing hole, you will need other equipment. A hole saw might not be the best option because it needs something in the middle to bite into. An existing hole is already empty in the middle and so there is nothing for the saw to latch onto. A Dremel or a Rotozip is better suited for enlargements. You might not get a perfectly round hole, but that doesn’t matter. A long as the diameter is right, you can hide any imperfections in the circumference with the grille.

If you are getting an exact replica of your old speakers, the mounting screw holes of the old speakers will line up perfectly with the new speakers. If you are getting a different set, which is more likely, you will have to drill new holes. To do this, hold the speaker over the spot where you want to mount it and mark the holes with a pencil and then drill.

Once the holes are drilled, it is time to connect the wires to the speaker. Take care to connect the positive and negative wires to the right terminals. You can use the existing tabs or join the wire end directly to the terminal. After the wiring is complete, screw on the speaker to the mounting surface. You might also want to apply a dab of silicone caulk to each of your terminals to make them water-resistant. Most marine-grade speakers also include rubber gaskets to prevent water from seeping into the cut-out hole. If your speaker does not have a gasket, you could apply a bead of silicone around the hole before screwing on your speaker to prevent water ingress.

Once all the waterproofing measures are in place, mount the speakers and tighten the screws. Your speakers are ready for use.

Additional Tips :

Positioning the speakers :

The speakers on your boat must be so located that you are able to point them at yourself at the correct angle. Since a boat has a lot of open space and there are no walls to reflect the sound, you will have to be extra careful while positioning the speakers. Also, stereo sound is any day better than mono sound. So make sure you have two speakers pointed at you and you are able to hear both speakers at the same time. A single speaker won’t be able to generate the same effect as a pair.

Wiring :

A marine audio system requires weatherproof wiring. Copper is highly corrosive and if you are using copper wires, make sure they are covered with plastic coating from tip to tip. Braided wires are not suitable for marine applications as they allow air to move around the metal making the wire susceptible to corrosion. Use tinned copper marine wire instead. The copper in the wire is specially treated so that it can stand up to the elements. You can also use 18-gauge doorbell wire or other solid core wire. Above all, remember to seal off all wiring connections with liquid electrical tape.

Connect positive speaker terminals to positive stereo outputs and negative to negative. If you are unsure which terminals are positive and which negative, hold an AA or AAA battery close to the speaker terminals. When the positive terminals meet, the speaker cone will move forward.