Wi-Fi afloat

Staying connected has been a major concern for voyagers ever since mailbags were tossed from out bound ships to those headed home. The work of Marconi, Tesla and other radio frequency tinkerers added more immediacy to the act of information sharing, and today, instead of Morse code being carried by continuous wave (CW) signals, packets of data fly on microwaves, bringing the Internet and other digital wonders to cruisers within reach of an electronic hotspot. In much the same way that ham radio caught the interest of serious long-term cruisers several decades ago, Wi-Fi has become a preferred link to land and a useful means of tracking weather, gathering technical information and just plain staying in touch.

Wi-Fi (wireless fidelity) is a brand name of the Wi-Fi Alliance, a consortium of high tech companies who have sought to improve local area network (LAN) operation via a wireless form of communication using the 802.11b protocol developed by the Institute of Electrical and Electronics Engineers (IEEE). Wi-Fi relays data signals via 2.4-GHz line-of-sight microwave-band radio. The system has gained worldwide acceptance and those using laptops with built-in Wi-Fi capability can sit in a coffee shop in their hometown or in an airport in Timbuktu and get online with no wires attached.
Wi-Fi operation
The hotspot, or range of the signal, varies from a room size area to a footprint of a square mile or more. Because Wi-Fi operation is a handshaking or send/receive self-checking protocol, transmit power is only half of the consideration when it comes to operational range. The ability to receive and decode weak signals is the other half of the equation. Antenna height and gain are big issues, and for sailors, this may not mean masthead height but it does mean a height well above the deck. Antenna gain is important but it’s one of those situations where too much of a good thing is actually a disadvantage. The double-sided sword when it comes to antenna gain is the issue of directionality. In short, the more range-increasing gain an antenna provides, the more directional its focus. The best compromise for boaters is about 8 to 10 dBi of gain that is either omni-directional in shape or enhances the signals received from the horizontal plane. Directional antennas can cope with 10 degrees of pitch roll or yaw — more than that will significantly impact the antenna’s signal detection capability.

Signal-to-noise ratio is another vital factor, and competing with Wi-Fi on or near the 2.4-GHz band are things like cordless phones, baby monitors, microwave ovens, security cameras and the world of amateur radio. Ham operators incidentally, are the licensed primary operators on this band space, and Wi-Fi users are considered unlicensed users, and in the eyes of the FCC have no right to complain about the up to 100-watt transmissions used by ham operators that can disrupt local Wi-Fi operation. Interference is not a huge problem, but it does have a noticeable impact on why one setup works well at one time and in one place and not in another.

Rather than bogging down in engineer-speak, we’ll take a modular look at how the system operates and what’s needed to improve your ability to find hotspots and tap into one of communication’s fastest growing sideshows. Most laptops and desktop computers sold today come with a platform such as Intel’s Centrino, a technology that utilizes a 2.4-GHz radio transceiver to connect the laptop automatically with a wireless access point or wireless router. This replaces the Ethernet cable that allows a personal computer to be directly connected to a network or linked to the web via a phone line, DSL or cable. Wi-Fi links up via a radio frequency (RF) signal. Relay nodes can be used to enhance the range of the signal handling and expand the footprint of the hotspot. Unfortunately, each relay hop that decodes and rebroadcasts the signal, adds to the problem of latency. In essence, the speed of light is actually too slow, and just as in some overseas phone conversations, where parties find a slight lapse between the talk and listen mode, Wi-Fi signals suffer a similar fate. Their circuitous passage through electronic circuits and switch labyrinths embedded in chips add up to these small time delays.

The simplest approach to Wi-Fi afloat unfortunately affords the least range. It involves the use of a conventional laptop equipped with a built-in Wi-Fi feature that works just fine in airports, hotels and Internet cafes. The all but vestigial built-in antenna has little gain and unless the hotspot is close by and figuratively lives up to its name, the signal will be lost.

The easiest to implement but only marginally effective first step to increasing range is to carry your laptop up on deck and see if the few feet of vertical rise and decrease in surrounding structure improves performance.
Remote antenna
Purchasing a remote antenna and more powerful signal booster will definitely increase the range of Wi-Fi reception. However, alternator RF noise, inverter ripple, radar and other sources of on board interference can cause problems and determining which impacts can be momentarily shut off to eliminate the interference makes sense. Some Wi-Fi users get away with remote inside-the-cabin boosters. Such devices are designed to sit on a shelf increasing the size of the antenna and power of the signal. These boosters can be purchased for under $100 and often answer the needs of many live-aboards who are not too far from the facility’s node.

Another option that’s especially appealing to those with a PCMCIA slot in their computer but no built-in Wi-Fi, is the purchase of a Wi-Fi card that fits this slot and also provides a plug-in point for an external antenna. The card, jumper and antenna can be found for around $200 from online RadioLabs and other sources, but the low power signal needs to be ducted through thick low loss cable in order to achieve the best results.

A better solution for some is to purchase an antenna with a built-in card. These devices directly link the antenna to the circuitry and can be connected to a computer with a lightweight Ethernet cable rather than thick low loss cable such as LMR-400, 600 or 900.

The top of the line solution is to mount a client bridge as near the antenna as possible and again feed the computer via an Ethernet cable. Some chose to add a wireless LAN to their boat but this extra layer of RF circuitry can really be asking for interference trouble. Alternators, inverters, DC motors and a wide array of appliances send out spurious RF noise, and the weak Wi-Fi signal is often the first to suffer. Hard wiring the link from the antenna to your computer using Ethernet usually affords a reliable, quality signal and better Wi-Fi operation.

Those ready to spend $500 plus for a top of the line client bridge, and $300 or so more for a Shakespeare 5248 Galaxy antenna, cable and connectors can often stretch a hotspot two to five miles from its origin, as long as you can place the antenna and bridge 10 or 15 feet above water level. Wi-Fi operates at microwave wavelength, and in addition to omni-directional and modestly directional vertical antennas, there are gizmos that afford much higher gain. These include grid, parabolic and Yagi-style antennas that have dBi ratings from 12 to over 30. Keep in mind that every 6 dBi of gain doubles the range. Unfortunately, these antennas are so directional that any pitch roll or yaw can turn a super signal into nothing at all. This is why the mid-range gain Wi-Fi marine antennas are about 8 dBi and remain the best for Wi-Fi afloat.

Moving the antenna out of the cabin improves Wi-Fi performance but also exposes the hardware to a chloride ion-rich environment eager to cause corrosion. As with all marine electronics, moisture protection and the use of the right cable are vital steps in the process. When a client bridge needs to be mounted close to the antenna and will be powered via Ethernet cable, protection from the elements becomes paramount. Many are sealed and can be mounted outside, but common sense should prevail and the less exposure to direct salt spray the better. Dedicated marine units provided by Syrens on board Wi-Fi, Port Network and RadioLabs are well-designed systems that can, under optimum conditions, reach hotspots five or more miles away.
Signal availability
The good news is that Wi-Fi is a worldwide protocol and the hardware has been designed with international use in mind. In the U.S., Wi-Fi users have access to channels 1-11, but when operating, adjacent channels are used, resulting in three actual channel alternatives (1,6,11). European Wi-Fi works on channels 1-13 and they pick up an extra operational cluster (1,5,9,13). Italy requires Wi-Fi users to register with a governmental agency, but most nations allow unlicensed access free of operational restrictions. Travelers can find free as well as for-a-fee hotspots in most developed coastal areas around the world. Marinas are moving from hardwire Internet access in favor of Wi-Fi. Those cruising the Med, Mexico and even Tahiti will find anchorages where a node is nearby.

There is plenty of debate over bootlegging on private wireless networks that haven’t been protected by a password. Many see this as a free drink at the communal oasis, while others view the practice as picking up a newspaper without dropping coins in the till. In addition to making your own decision about how much free riding should be done on someone else’s hardware, comes the question about how much microwave energy do you really want flying around your cabin. Health disclaimers and articles about RF propagation and its effect on the human body are becoming more and more prevalent. A reasonable approach seems to be the use of an antenna to Ethernet cable to computer rather than an on board LAN. This will yield better Wi-Fi signal quality and less exposure to RF energy.

Staying connected in a wireless world is easier than ever, and Wi-Fi can be a valuable link for coastal voyagers who cruise from one hotspot to the next. 

By Ocean Navigator