02 - Boost Your Mobile Signal
With a Small Investment of Time and Money, You Can Boost Your Mobile Signal Onboard

A mobile phone can provide a great deal of functionality onboard a boat, from obtaining weather forecasts to sending blog posts, but all this technology only works if you can get and stay connected to cellular towers.

What good is an up-to-the-minute weather forecast if you can't connect to read it? Think back to the days when mobile phones were new (and much larger). Remember going in search of that sometimes elusive signal - standing by the window, stepping outside, maybe even walking to the top of the hill. Well, on your boat you may be returning to those nostalgic times.

Of course, those of us who live on the coast of Maine and other rural locations never left. For example, here in Castine, the sweet spot is on the town dock. You may have to stand up on one of the picnic tables and face southeast, but don't worry. We're used to that. Mobile phone cell tower Mobile phones depend on towers for a signal, and where they are located matters.

First, we will explain why, despite huge investments by the mobile network carriers, the signal on your boat remains poor - sometimes even worse than it was a few years ago. Then we'll go over some of the equipment that is available to solve the problem. With a small investment and a little work, you can greatly increase your mobile network access.

We'll discuss built-in solutions that offer choices of amplifiers and antennas, and require stringing cable through your boat. We'll also discuss new equipment that can increase your signal strength for less than the price of traditional amplifiers with virtually no installation. One of them is bound to be the right solution for you.


Your mobile phone is a radio much like your VHF radio. Electromagnetic signals are sent through the air so you can communicate with others. On your VHF radio there is a distance range outside of which you cannot reach another VHF radio (the rule of thumb is generally line of sight). This range is relatively long for your onboard VHF, which usually has a signal output of 25 watts, and quite a bit less on your handheld VHF, which generally has an output of just 5 watts. In either case, you cannot communicate unless there is another VHF radio within your signal range.

The same is true for your mobile phone, except your phone's signal is going out to cellular towers which are routing that signal to the desired location. As we are all aware, if you are out of range of the cell towers, you will not have a signal.

On our boats we have VHF antennas - typically large ones - to extend the signal range. In comparison, mobile phones have tiny antennas; most so small they are actually inside the mobile phone. Now some of you are thinking, I bought an external antenna for my mobile phone and it didn't help one bit. That is most likely true. In fact, by the end of this article you will understand why doing this can actually make your signal worse than if you had no external antenna.

So why is your cell signal often so poor on your boat? Well, the first reason is fairly obvious. On a boat we are frequently heading to remote locations. After all, isn't that the point of being on your boat - to get away? Remote areas are often underserved by mobile companies. That's why we have poor mobile service in rural Maine and good service in New York City: mobile carriers focus their investment on equipment in the locations that will give them the biggest bang for their buck. More remote areas will tend to have fewer cell towers and those towers often have older technology.


But that doesn't explain why your mobile phone service may have actually gotten worse on your boat over time. Mobile phone cell tower Companies are moving to a model that calls for more towers with less reach.

It is true that more cell towers appear every day. However, these towers are focusing on the largest population. They are therefore generally directed inward towards land and away from the water. After all, there are typically more people on land than on the sea (you may dispute this on a beautiful Saturday in July, but we assure you it is true). So even when new cell towers are installed in more remote areas, they are most likely pointing away from your boat.

In addition, many mobile carriers are moving away from cell towers that reach out to a broad area in favor of more towers with less reach. They have found that this provides better coverage and quality - if you are on land. Cell towers big range A small number of towers paced along the coast, each tuned for more range. This gives some signal access offshore.

Cell towers broadcast in a circle around the tower. Under the old scenario, a tower that happens to be close to the water would project out over the water. (See photo.) But by putting in more towers that broadcast in smaller circles, the coverage on land remains good or improves, while the coverage on the water may be reduced. Check out cell tower coverage in your area.

And the mobile carriers aren't the only ones sabotaging your signal strength. The Federal government is involved, too. In the same way your VHF has a much bigger antenna than your mobile phone, it also has more power, which allows it to send out a stronger signal. The Federal Communications Commission limits the power on mobile phones.

This actually makes sense for the typical user. Just think of how many mobile phones are being used at once in your average shopping mall. If these phones were all blasting away at high power, the interference would prevent them from all working at the same time.

Your dashboard VHF radio typically has 25 watts of power and your handheld VHF usually has 5 watts of power. But the FCC limits the power on a mobile phone to about 0.3 watts. That's a substantial difference. So you have a device sending out a less powerful signal using a tiny antenna. Add to this the interference from the other electronic devices on your boat and the boat itself and it is amazing we are able to get a signal at all! Cell towers small range There are more towers but with less range. The result is decreased access on the water.

Luckily there are a variety of inexpensive to reasonably-priced solutions available that can greatly boost your signal, allowing you to use your mobile phone in all but the most remote locations. These devices will enhance both your access to voice connections, letting you stay in touch with loved ones and giving you another form of communication in emergencies, and to data, offering increased safety and convenience through access to real time weather and marine databases, such as the ActiveCaptain website.


First, we will mention some simple solutions that for many of you will provide just the boost in signal you need. If the idea of installing an amplifier, antenna and the necessary wiring seems a bit overwhelming, there are some interesting new products that offer portable cellular amplification with virtually no installation that really work. We'll be honest here, when we first heard of these devices we were skeptical. But we've been using them in a variety of environments and have found that they work very well.

We introduced the Cell Ranger to the boating community last fall and even have carried it on our web site. Many fellow Captains have been using Cell Rangers on their boats with much success. Fortunately for those of us who are "techno geeks", there are always newer products on the horizon. Wilson Electronics, an industry leader in cellular amplifications, now has the MobilePro, which offers more flexibility than the Cell Ranger, but slightly less amplification. We think you'll see more portable amplification products available in the future.


If you feel you need an greater signal boost than provided by the portable solution you will need an external antenna and an amplifier installed on your boat, and they will have to be installed correctly. Let's look at some of the information you need to purchase the correct equipment.

You may remember from the first article in this series that in the U.S. there are two broad types of mobile networks, GSM and CDMA. Like all radios, your phone will communicate across certain frequencies. The specific frequencies used will depend on which type of mobile network you have. In the U.S. there are four ranges, typically referred to as 850, 900, 1,800 and 1,900 MHz. For this discussion it is not important which one you use, but you will most likely see these terms so you should be aware of what they mean. Note that all of this becomes far more complicated when you move outside the U.S., so we will focus here on U.S. installations only.

To get a signal you must be able to reach the correct frequency. The good news is that you do not need to worry about this for your phone if you are purchasing it from your carrier, because AT&T, Verizon, and other companies will ensure that the mobile phone they provide you will match their frequencies. However, you will need to consider these frequency issues when selecting a compatible amplifier and antenna.

Other terms you will see are Multi-Band, Dual-Band, Tri-Band and Quad-Band. This refers to the number of frequency bands a device supports. They are called "bands" because they actually cover a range of frequencies. For example, the "1,900 band" spans frequencies from 1,850 to 1,995 MHz. These terms do not define which bands are supported and they often will support frequencies outside of the U.S. This is typically true when you purchase a quad-band amplifier.


How do you know which amplifier will work with your phone and carrier? Most suppliers - companies like Digital Antenna and Wilson Electronics - make this fairly easy. They allow you to select the amplifier by cellular provider or by the specific make and model of your phone. This information will allow them to suggest an amplifier that will work well for your configuration. In general, you should select a multi-band amplifier to give you the most options and flexibility in the future. There are amplifiers that will work with both AT&T and Verizon, for example.

The next question is whether to use a "direct connection" amplifier or a "wireless" amplifier. A direct connection amplifier requires a cable between the amplifier and your mobile phone. A wireless connection amplifier re-broadcasts the signal and can allow multiple phones to access the amplifier from almost anywhere on your boat. While the wireless solution certainly sounds like the winner, on most boats they will not work properly. An amplifier An amplifier, if properly installed, can boost signal strength.

A wireless amplifier has an inside and an outside antenna. The inside antenna grabs the signal from your mobile phone, amplifies it, and re-broadcasts it over the external antenna. The problem in many boats - pretty much any boat under 100 feet - is that the inside antenna will end up too close to the external antenna, or not isolated enough. This causes feedback between the two antennas.

Remember that awful squeal you've heard when a microphone is too close to a PA system? That's feedback. The good news is the amplifier is designed to prevent that horrible noise from occurring (it would burn out the amplifier). The bad news is that it does this by detecting the feedback loop and automatically reducing the amplification. The result is no feedback - and reduced amplification. The signal becomes so reduced that it eliminates most or all of the gains you made by buying the amplifier.

Note that an exception to this has been seen on steel boats. The steel super-structure can help to provide separation between the antennas which will eliminate the feedback. This separation doesn't happen on fiberglass or wooden boats, however. Sailboats with the outside antenna on the top of the mast will provide good separation for a wireless solution also.

For most boats a direct connection is the only alternative. While this solution is somewhat limiting - you must have a cable that runs from the amplifier to your mobile phone - it is also the most reliable. The best way to connect the phone is with an antenna jack on the phone. Many phones do not have an antenna jack, though higher-end phones generally do. If the phone doesn't have a jack, there are cradles that can be used. If you have the choice, a jack is better and should be a consideration in selecting a mobile phone for your boat. We discuss more about selecting a mobile phone for your boat in other articles in the series. Phone in cradle Cradles can connect a phone to an amplifier, but direct connection is better.

With a direct connection amplifier to your mobile phone, it is possible to connect your laptop "wirelessly" to the Internet or even talk wirelessly. We discuss this in more detail in the article 'Connecting a Laptop'. For now we will just cover the physical setup. Your mobile phone is directly connected to the amplifier and communicates to your laptop via Bluetooth or WiFi. We have used this setup for our last several cruises and it works very well.


When selecting the antenna, we urge you to consider only marine grade equipment by companies such Wilson Electronics, Digital Antenna, Shakespeare Electronic or others, especially if you do your boating in saltwater conditions. Non-marine antennas will quickly degrade in the typical marine environment and any savings you might realize will be lost when you are forced to replace them. Marine antennas will also include mounting options that are appropriate for your boat.

Another potential problem is line loss. Some of you may have tried adding a simple antenna alone (without an amplifier) and saw no increase in signal strength. Some may even have seen signal strength decline. Let's look at why this happened to help you better configure your boat.

When a signal passes through a cable, there will always be a reduction in the strength of the signal. This is known as line loss, or attenuation. The amount of line loss that occurs depends on the distance the signal must travel through the cable and the quality of the cable used. The greater the distance traveled, the more signal will be lost.

This loss is also increased by using poor quality cable. A general rule of thumb is to use the best quality cable you can find. The price of good quality cable is not significantly higher than poor cable, while the benefits can be significant. When wiring up the amplifier to the antenna, we suggest using LMR-400 type coaxial cable. This cable provides the lowest line loss and is very easy to find. It is also fairly stiff and difficult to work with, so plan for this in your installation. You can easily calculate line loss for your installation.

Our last piece of advice about cabling is to have as few connectors involved as possible. Each connector will cause additional line loss, so a straight cable from your antenna to the amplifier is better than one that has a connector in-between. Make the cabling simple between the amp and the antenna.

Nowhere is line loss more profoundly demonstrated than on some sailboat configurations we have encountered. The typical scenario is that the captain and crew decide they need better mobile phone coverage. They want another emergency communications device and an easy way to access the Internet and email, so they purchase an antenna that promises to double their cell signal. They want to ensure their antenna can see the cell towers "from anywhere," so they decide to put this antenna at the top of their 40 foot mast. The signal coming to that antenna may be enhanced by the antenna, but they also have more than 40 feet of line loss. In addition, a low quality cable has often been used. After all, 40 feet of high quality cable is more expensive and, due to its stiffness, would be difficult to maneuver through the mast. It is quite conceivable that the signal they end up with is less than what they had before using the antenna. They may have had better results by just standing up outside with the phone in their hand! Coaxial cable LMR-400 coaxial cable is recommended to cut line loss.

But all is not lost. The way to remedy the line loss problem is by installing that amplifier we discussed, before the external antenna. Amplifiers are allowed to increase the small 0.3 watt mobile phone signal to a whopping 3 watts of signal output - 10 times what the phone itself can put out.


This is a good place to point out that doing the installation yourself is not at all unreasonable. It is no more difficult than installing a VHF radio with antenna. Of course, there are also many electronics installers who can do it for you. Make sure they have experience installing this equipment, and that their experience is in the marine environment. If they don't know what LMR-400 is, look for someone else.

In addition to selecting and purchasing the right equipment, you will also need to determine where to place it. There are a few things you should weigh in order to obtain the best possible signal quality.

First, consider placement of the amplifier. You will most likely want it in an out of the way location. It is something you will rarely need to access and, quite frankly, they are pretty unattractive. It will require a typical 12-volt DC power source, and there will be times when you may need to access the unit to check a cable connection or some such thing. Because this is most likely to occur at the most inconvenient time, when access to your mobile signal is critical, it pays to install the unit in an area that is not too painful to reach. So find a place in the ceiling or behind a bulkhead, preferably where you can get to it without unreasonable hassle.

But proximity to the antenna is also very important. If you are looking at several possibilities for the amplifier location with similar convenience factors, select the one closest to your antenna location to cut down on line loss. You'll also save money on cable costs. The same goes for the antenna. Placing it at the top of your mast may not be as good a location as on the stern railing. The antenna simply needs to be where it has a clear view of the sky.

Once your project is scoped and the equipment is purchased, be sure to follow all safety procedures associated with proper marine electrical work, and call in a pro if you feel uncertain.

The bottom line, however, is that amplifiers work. Our experience is that they operate wonderfully in most boating situations, even several miles offshore. We've used a mobile phone as far as 20 miles off the North Carolina shore when it was connected to our amplifier. We've traveled from the Penobscot Bay in Maine to Key West in Florida while maintaining a continuous Internet connection with the exception of 25 miles on the Pungo-Alligator Canal. An amplifier will give you 3 "bars" when your mobile phone detects no signal on its own.