I hooked up my new Ubiquiti Bullet2HP to a 12v source and I am making this post using it right now. Really nice.
Of course, I'm very close to my own wireless access point at home, in fact there's no antenna connected to the Bullet. I'm using a 12v spotlight battery for power. When I get to our boat, I'm going to hook it up to the mystery antenna at the top of my mast. Once that's accomplished, you can be sure I'll have my pick of wireless networks to use.
To hook this up, I got a piece of normal Cat5 cable and carefully stripped off the outer plastic shell, revealing 4 pairs of wires. I hooked +12 volts to the blue pair (solid blue and blue striped), and ground to the brown pair (solid brown and brown striped). The Bullet immediately powered up with the "on" LED lit up. The other 2 pairs of wires remained connected to the plug at the end of the cable. I plugged that plug into my laptop. Then I followed these instructions: http://www.ubnt.com/downloads/Nano_Quick_Set-up.pdf
The instructions are for another product, but they are close enough to figure out what to do.
If you aren't comfortable stripping wire (or stripping striped wire), you can get a Power Over Ethernet (POE) device, that breaks-out a power connection for you. There's a simple one that costs about $6 that I saw online, that would be suitable for use on a sailboat. Other POE "injectors" may be starting with 110volts, where you don't have to.
Once you have it setup, you can have it automatically find wireless networks, or you can set it so you can choose which wireless network you want to connect to. The former may connect you to a less-than-optimal network (perhaps a strong signal coming from another boat that is also simply a repeater), while the latter method would have to be done at each new anchorage. I went with the former, but I can easily change it through the web interface that the little device has built into it.
Here's the setup:
When I do install it, I plan to wrap it in electrical tape like the installer did for this one. Actually, I'll wrap the tape lower, since a few (actually, ten) Bullets had leaks under the clear cover that's over the LEDs -- bad glue that they've since fixed. To help it last a long time, I'll probably use electrical tape down to right below the LEDs. White tape would also look better too.
You'll need to get a WiFi (2.4 GHz) antenna with a female "N" type connector. The Bullet attaches right to the antenna at the top of your mast - no antenna cable. You have a Cat5 cable carry the signal (and power) to the unit. This eliminates the signal loss that you usually get from running a coax cable up to the mast. Here's an example:
When you unscrew the lower cover, you can see where the Cat 5 cable attaches. The lower cover has a hole for the cable that has white plastic O-ring. I tore it while removing it, so be careful when taking that grommet off the unit and sliding it over the Cat 5 cable. I plan to tape it up pretty thoroughly with electrical tape, so no harm done.
Choose an antenna that's right for the amount of pitching and heeling/rocking you will be doing when you surf the Internet. Unless you are at a dock or otherwise facing a specific direction all the time, you'll want to get an omnidirectional antenna. These antennas are available in increased gain, but the higher the gain, the narrower the vertical width of the beam. So heeling and pitching will affect a 12db gain antenna much more than a 6db gain antenna. From some cursory research, 6db to 10db ought to work. Since I plan on using the Internet mostly at anchor, if I didn't already have an antenna, I'd go for an even higher-gain omnidirectional antenna, maybe even 15 db or more. The higher the gain the longer the antenna gets, it seems. A 15db omnidirectional antenna will probably be 70 to 90 cm long and pull in signals from pretty far away. We'll see what range I get with my set up, using an unknown antenna that came with our boat.
At home, with no antenna, I pulled in my own wireless network. By holding a 6 inch wire onto the antenna plug, I could see 3 wireless networks. I can only imagine what I see once I get a real antenna connected.
Finally, I may hook a Linksys wireless router to the Bullet, so that I have WiFi in our boat. From what I understand, the Bullet can be setup as a repeater and serve your wireless laptops on your the boat, but I may use a separate device anyway (something about throughput). But initially I'll use a wire to my Bullet. I can get it setup that way quicker and I will be burning less amps (8 Amps, I think).
There is a forum for this product. Some useful threads are there. (Careful, one of the threads linked to an antenna with a female "type N" connector. You will need a male connector.)
marine wifi?? - Ubiquiti Networks Forum
Best Marine Antenna for B2HP Bullet - Ubiquiti Networks Forum
For the techie types - and if you made it this far then you are one - here's the datasheet: http://www.ubnt.com/downloads/b2hp_datasheet.pdf
Here are some places to buy it: bullet2hp - Google Product Search
Note that you choose how powerful you want it to be. I got the 800 mW one by accident because I didn't pay close enough attention. I'd go for the 1000 mW one. It costs a bit extra, but considering the effort to get everything in place and buy an antenna, it's worth it.
***EDIT: I'm not affiliated with Ubiquiti, not related to anyone there, don't even know anyone there. I saw the product mentioned in another WiFi thread and thought I'd try it out.***