Wireless Wiki

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Making shore-based Wi-Fi Internet work well on a boat.

Tip: See also Wi-Fi (main article), Wi-Fi How To, Fast Fixes to Wi-Fi Problems, and Cellular on a Boat

Common Problems[]

In locations where shore-based Wi-Fi signals are strong, using them for Internet access on a boat is comparable to using Wi-Fi hotspots on land. However, the marine environment tends to exacerbate general Wi-Fi problems and create other problems of its own:

  • Boat hulls and sailboat masts can block radio signals, reducing range.
  • Movement of other boats can cause interruptions of Wi-Fi connections.
  • Location of a Wi-Fi antenna in a cabin below deck can further reduce range.
  • It may be difficult to get close enough to the Wi-Fi access point for sufficient signal, especially when anchored.
  • Boat movement can result in aiming problems with highly directional antennas (even when tied up).
  • Moisture in the marine environment can result in electronic failures.

Improving Wi-Fi[]

Higher Power[]

American Alligator

While it may seem that higher power Wi-Fi might help to improve your range, that's not necessarily true, since higher power only helps on transmit, not receive. Thus it's only likely to help if the other end of your connection is using higher power as well, which may not often be the case. In other words, what you may well wind up with is an alligator, big mouth but small ears. Also, unnecessarily high transmit power will tend to increase your interference with other Wi-Fi users, making you a bad neighbor. However, if the other end does have a powerful transmitter, at least you can have the same matching power level at your end. Improving your antenna will help both transmit and receive.

Better Antenna[]

Outdoor wireless access point with high-gain omnidirectional antenna.

Usually the best way to improve range is to use a better antenna (or reflector with a standard antenna), which helps both transmit and receive.

Better antennas work by being directional:

  • concentrating radio energy/sensitivity to/from the desired direction instead of wasting it in pointless directions, and
  • reducing interference from other radio sources not in the desired direction (path).

The improvement in antenna performance is referred to as gain, where a higher number indicates the amount of performance improvement expressed in dBi. It takes an increase of 6 dBi to double range; e.g., as compared to a typical 2 dBi antenna, an 8 dBi antenna has double the range.

However, a highly directional antenna can be problematic on a boat, since it must be kept aimed accurately at the remote end of the connection, which can be difficult on a boat floating in the water (even when tied up). The width (angle) of the directional pattern (both vertically and horizontally) can be used to see how accurately the antenna must be aimed.

The simplest and easiest improvement is to use a higher-gain omnidirectional antenna (4-8 dBi), thereby avoiding the need to aim the antenna horizontally (point it at the shore-based wireless access point). Such an antenna works by concentrating energy/sensitivity in the horizontal direction that would otherwise be wasted vertically (up and down). Beyond about 8 dBi the vertical beam angle becomes so narrow that vertical aiming can be problematic on a boat:

Antenna Gain
Example of
Vertical Beam Angle

4 dBi
6 dBi
8 dBi
10 dBi
12 dBi

Omni Antenna Patterns.svg

There is a fair amount of discussion here about beam width and why a boat must have an omni antenna with about 8 dBi or less gain. Let us do a practical test of this. Take your hand bearing compass out and site a location about 1000 feet from your boat. Then slowly turn six degrees and look at that point. Now imagine that distance turned vertically and that is the beam with of an omni antenna with a beam with of 6 degrees at 1000 feet. Repeat this for a point 2000 feet away, then 3000 feet away, then 6000 feet away. This test convinced me to experiment with high gain omni antennas from the practical perspective of a sailing boat. I am not disagreeing that at close proximity that a lower gain antenna is better. But as the distance increases the effective beam width increases. Years of actual experience aboard sailing boats confirms that higher dBi gain omni antennas work well on a boat at anchor as well as at a dock close to the shore side station. However, there is a limit. In the United States, the Federal Communications Commission (FCC) regulates the use of antennas through FCC Part 15.247, which defines power limitations for Wi-Fi devices. The key to applying these rules is to understand EIRP (Equivalent Isotropically Radiated Power), which represents the total effective transmit power of the radio, including gains that the antenna provides (and losses from the antenna cable). For antennas with gain greater than 6dBi, the FCC requires you to reduce the transmitter output power if the EIRP is already at the maximum of 36dBm (4W). This means that as antenna gain goes up, you must decrease the transmitter power. Higher gain antennas would mostly apply to point-to-point solutions having very long range requirements, which is not used for multipoint Wi-Fi hotspot access applications (point-to-multipoint). When using omni-directional antennas less than 6dBi gain, the FCC rules require EIRP to be limited to 1W EIRP or less.

Antenna Location[]

Higher antenna locations tend to have less interference from obstructions (e.g., biminis, dodgers, booms, and other very close proximity boats) than lower locations since there are more obstructions on a boat closer to deck level, so in general, it's a good idea to locate the antenna as high as is practical. WiFi is line of sight, and the use of a medium gain antenna (4dBi-9dBi) will provide a fair amount of flexibility in accessing WiFi access points on shore regardless of the height of the antenna on the boat due to it's wide cone of transmission. Use of a higher gain antenna (12dBi - 15dBI) may cause you to have a need to adjust the height of your antenna based on the access point location since the cone of transmission is significantly smaller than on medium gain antennas. Height is important to get clear of nearby obstacles and for maximum range. VHF antennas are mounted at masthead for the same reasons.

Since signal loss in the cable between the radio unit and the antenna increases rapidly with the length of the cable, it's better to locate the radio unit next to the antenna, and use lossless cable to support the radio unit, either USB or Ethernet, both of which have advantages and disadvantages (as noted below).

Automatic Tracking[]

There are products than can be used to keep a directional antenna aimed at an access point as a boat swings or drifts with precision of better than one degree (e.g., Track-It-TV). However, they are relatively expensive, and they only track in the horizontal plane, so it's important that the vertical beam width take into account rolling and pitching of the boat. Usually a vertical beam angle of 10 degrees or so is adequate for all but the roughest conditions, but even beam angles of 20 degrees or more can still result in substantial improvement in gain over an omnidirectional antenna.

There are hobby projects to build an auto-aiming directional antenna capable of staying locked into the best signal while a boat rotates around an anchor line.

Temporary Setup[]

Setup as needed, packed away when not in use. Ideally the radio unit and antenna are located together as high as possible (e.g., outside on the top of the cabin), usually connected by cable:


Hawking HWU8DD Hi-Gain USB Wireless-G Dish Adapter


  • Plug and play (check manufacturer's specifications)
  • Low cost (desktop type devices).
  • Power provided by USB cable, directly from the computer so no additional cabling is required.
  • USB Devices are designed for portable applications with quick (i.e. boat moving from port to port) setup.
  • Can often be used onshore as well as on the boat.
  • Using a software based access point (ICS), you have the ability to connect multiple computers or devices that use only built in Wi-Fi (such as smart phones and tablets) with no additional hardware.
  • Some products integrate directly into the operating system making their use as simple as built in WiFi adapters.


  • Maximum length of a passive USB cable is 5 meters (about 16 feet), although that distance can be multiplied by means of one or more USB active extension cable(s), effectively a standard USB cable married to a one-port USB hub. (e.g., StarTech USB 2.0 Active Extension Cable USB2FAAEXT15).

    1 Watt USB Adapter with antenna

  • Requires software drivers to be installed before the WiFi unit can be used. (Check with manufacturer to assure compatibilty with your particular operating system as not all units will work on all operating systems.)
  • Potentially more complex connection sharing. USB Internet connection can be shared by means of Internet Connection Sharing (on both Windows and Mac OS's). If using Microsoft Windows 7, this has become simplified via "Virtual WiFi". Connection Sharing through your computer will require the sharing computer to be left on whenever connection sharing is needed with additional hardware and electricity requirements, since hosting computer must be left on, in order to allow these other devices to get online.
  • When running from a laptop battery, the power consumption of a high power Wi-Fi device will deplete the battery at a higher rate than if using the computer with no external devices attached (maximum USB port power is 500mA at 5v). The actual rate of power consumption by a USB device will be dependent on the device being used, so check manufacturer's specs for power draw.

Typical USB setup:


Buffalo Wireless-G High Power Ethernet Converter WLI-TX4-G54HP


  • Long cable (up to 300 feet or 100 meters) - installations at most advantageous locations becomes achievable (i.e. masthead).
  • No software drivers needed by computers. Firmware built into ethernet based devices control Wi-Fi access. This makes hotspot selection changes more flexible since any computer or device is capable of doing this via a browser. Some interfaces of these devices were designed for networking professionals so check with manufacturer for information about operation.
  • Ability to create private networks using switches, hubs and wireless routers. Ability to connect multiple computers or computers that do not have Ethernet or USB connections and use only built in Wi-Fi (i.e. phones, tablets, TVs, etc.).


  • Client bridges, repeaters, and routers all require a source of external power. Devices require either a power cable or PoE (Power over Ethernet). Check manufacturer spec.
  • Depending on supplier, configuration and management can be more difficult for average

    Wi-Fi for Boats Omni antenna and Wireless Ethernet Router.

    computer users. Check supplier specs.

Typical Ethernet setup:

  • Coastal Marine WiFi includes waterproof enclosure for the Bullet, custom dual PoE injector for single power connection, and preconfigured AP router to provide a hotspot on your boat. Uses standard 1"-14 mounting, and includes Android/iOS apps
  • Bitstorm BAD BOY Xtreme N and Xtreme MJ, Unleashed N Built-in router. Lots of general Wi-Fi information on their site. (Rail mounted shown at right)

Hybrid Solutions[]

There are a new set of solutions that are coming to the market that combine the benefits of both USB and Ethernet based systems into an extremely easy to use package and provide a full onboard network for your boat as well as give you long range connectivity to shore-side access points.


  • Single hardware and cable installation, no Ethernet or USB cables to use.
  • No software to install, connect 12V power and connect over WiFi.
  • One user interface to manage both local network and connection to remote access point.
  • Power supplied by standard 12V power cable. Typical draw is < 500ma.
  • Unlimited cable length, allows unlimited mounting possibilities.
  • Built in Access Point allows all devices to share the WiFi connection simultaneously.
  • Management of the device can be performed by any WiFi enabled device with a web browser (ie PC, Mac, iPhone, iPad, etc)


  • Depending on supplier, configuration and management can be more difficult for average computer users. Check supplier specs
  • If the private Wi-Fi hotspot to connect your devices onboard is built into the same box as the Wi-Fi transceiver, there is a trade off: If the long range Wi-Fi transceiver is located high for best reception, the private hotspot is up there as well, not down where the devices connecting with it are. If the transceiver is left low to facilitate connection with devices, the transceiver may not get the best possible connection. However, with high power equipment like The Wirie AP+, the private hotspot is accessible regardless of mounting location.
  • Where the local AP is located away from the antenna and WiFi radio, ethernet cables have to be installed, which may or may not be a problem.

Typical Hybrid setup:

  • The Wirie AP+ - Long Distance, Easy to Use, Simple Installation, Affordable - Marine Grade, for Boats and RVs. Built in access point, 12V power source. Upgradeable to support 2G, 3G, and 4G.

Lightning/Surge Protection: This may protect your investment although lightning suppressors may cost as much as the Wi-Fi equipment itself.

Permanent Installation[]

[[Image:CA World WiFi 250mW Outdoor WiFi transmitter -

WL24005 Outdoor AP/Client

.jpg|thumb|CA World WiFi WL24005]]

Any permanent mount solution mounted above deck level will give far more range and signal quality than regular Wi-Fi at deck or cabin level.


  • Install marine-grade waterproof high-gain omnidirectional antenna. Non vented sealed type antenna recommended as any water ingress into the antenna will reduce the life of the antenna. Avoid the use of dish or directional antennas.
  • Install weatherized Ethernet device (e.g., Bitstorm BAD BOY Xtreme, Ubiquiti Bullet, SENAO SL-2611CB5 EXT or SOC-3220) as close to antenna as possible in order to eliminate signal loss in antenna cable. (See picture at right for an example mounting using the Ubiquiti Bullet 2HP.)

    Masthead mounted Bitstorm Xtreme resulting in no signal loss due to cabling.

  • Run outdoor rated CAT5 cable from Ethernet device.
  • Devices are powered via Power Over Ethernet (power requirements vary by manufacturer). Some devices operate directly from 12Vdc.
  • At cabin end of Ethernet cable, attach:
  • Your computer
  • Hub or switch for wired network connections
  • Wi-Fi access point for private Wi-Fi rebroadcasting (e.g. Bitstorm BAD BOY Unleashed N )
  • Bluetooth access point (e.g., ANYCOM AP-2002) (for Bluetooth network connections)


  • Install marine quality USB device with non-vented omnidirectional antenna mounted next to the WiFi adapter. (e.g. The Wirie)
  • Run the USB cable into your boat from the WiFi system.
  • Extend the USB cable as needed to location inside your boat. Use Active USB extension cables to extend the length.
  • Install software for the WiFi adapter on any computer you want to use with the WiFi adapter.
  • If desired, set up Internet Connection Sharing on a single computer to allow multiple computers/devices to access the USB WiFi device simultaneously.

Hybrid Solution:

  • Install marine-grade waterproof high-gain omnidirectional antenna mounted with a Hybrid WiFi Adapter/Access point (e.g., The Wirie AP) .
  • Antenna should be non vented type as any water ingress into the antenna will reduce the life of the antenna. Avoid the use of dish or directional antennas.
  • Run marine grade DC Electrical Cable to a 12V power source.
  • Connect to your local HotSpot over WiFi to manage both your local network and the shoreside connection.
  • Allows all your computers and devices (phones, tablets) to share the internet connection and manage the connections to shore.

Managing a Wireless Ethernet Bridge[]

Wi-Fi at top of sailboat mast

When using a wireless Ethernet [client] bridge, IP addresses of networked clients on the boat (wired or wireless) are normally assigned by a shore-based DHCP server.

The problem is that the wireless Ethernet [client] bridge will typically have a fixed IP address for management that won't necessarily be on the same subnet as IP addresses set by shore-based DHCP servers, preventing networked clients from directly managing the wireless Ethernet [client] bridge.

Possible solutions to this problem:


  1. Use a client (ethernet adapter) that incorporates router functionality to create your own LAN (example Bitstorm BAD BOY Xtreme N and Xtreme MJ). By adding a wireless hotspot (i.e. Bitstorm Unleashed N), you can share the single internet connection simultaneously with several computers. Another advantage is that even though multiple devices and connect and share the internet connection simultaneously, only a single connection to the Wi-Fi access point is used. This is a big cost saving when connecting with hotspots that charge per connection.

More Complex:

  1. Use two network adapters {wired or wireless) on a given networked client:
  2. One configured by (shore-based) DHCP for Internet access
  3. The other configured manually just for managing the wireless Ethernet [client] bridge
  4. Use a multi-homed Ethernet adapter with both a static address and a DHCP address

Wired versus Wireless Clients[]

Boat Wi-Fi Wired vs Wireless.svg

Note: In order to maximize throughput, a private boat Wi-Fi access point should ideally be on a different minimally-overlapping channel (1, 6, 11 in the USA) from the shore access point.


Many standalone low-end networking devices that use separate "wall wart" type power supplies are able to tolerate a relatively wide range of input voltage, and can be run directly from 12 VDC boat power with an appropriate adapter cable. Check manufacturer input voltage specs if possible.

One advantage of the Ubiquiti systems (the Bullet 2HP or the Nanostation 2HP) is that they run on power over ethernet which can be "injected" using a passive PoE injector (like $5) wired straight into 12VDC. Getting an injector with separate power and lan leds is a good idea, since you can figure out the polarity without having your device plugged in.

LAN on a boat[]

  • When the boat has its own wireless access point (or wired hub or switch), and multiple network devices that get their IP addresses from a remote DHCP server, then all those IP addresses will be on the same subnet, and are thus part of a local area network (LAN). It won't necessarily be a private LAN -- unless the remote wireless access point implements wireless-to-wireless isolation (which many or may not be implemented), and boats may be on the same LAN, and you should take precautions accordingly -- see Secure Internet access in a public hotspot. This kind of LAN will be operational only when connected to remote Wi-Fi.
  • To have a private LAN, and one that works even when not connected to remote Wi-Fi, then use a Wi-Fi receiver that incorporates router functionality like Bitstorm Bad Boy Xtreme N and Xtreme MJ.
  • Another solution is using a product like The Wirie AP+ that has a built in local WiFi network to provide the LAN, built into a single product, so only a single piece of hardware must be installed to provide both remote WiFi connection, and a local onboard network.
  • If using an Ethernet (client) bridge, access the LAN management port of the wireless by:
  • Good method: If supported by your local wireless router, configure a manual route from LAN to WAN for a (RFC 1918) private IP address on the LAN management port. (The wireless router shouldn't forward private addresses without a manual route.)
  • Crude method: Set a fake non-conflicting public IP address on the LAN management port of the wireless Ethernet (client) bridge, which your local wireless router will automatically forward to its WAN port (since it's not a local or private address).

Relaying and Mesh Networks[]

When some boats are too distant from a shore access point for a direct Wi-Fi connection, it may be possible to setup nearer boats to repeat or relay the Wi-Fi signal to more distant boats. See Wireless Distribution System.

International Use[]

Wi-Fi channels are standardized, but vary slightly in different parts of the world. Many Wi-Fi devices will work properly anywhere in the world, either by means of a configuration option (preferable), or by means of different firmware loads (clumsy). See Wi-Fi Channels. Check whether a suppliers has included a simple method to conform to the Wi-Fi requirements of different countries. For example: The Wirie AP+ and Bitstorm Bad Boy Xtreme N and Xtreme MJ provide this as part of their management application and configures it to operate within the legal requirements for the selected country.

External Links[]

  • The Wirie AP+ - Long Distance, Easy to Use, Simple Installation, Affordable - Marine Grade, for Boats and RVs. Now supporting 2G, 3G, and 4G data connections AND long range WiFi.
  • Wi-Fi for Boats - You Can't Connect To A Station You Can't Hear
    Use our 15 dbi High Gain Omni Antenna to hear the weak signals.
    "It works beautifully!" Bill Campbell, S/V Alcheringa II