Cruisers & Sailing Forums - View Single Post - Long-Distance WiFi Device

Gashmore · 20-03-2009, 05:05

That Hawking corner antenna would work for a marina queen but is pretty well useless if the boat actually goes somewhere. There are two ways to increase gain with an antenna. Make it directional or flatten the doughnut. Making it directional is not the way to do it in a mobile installation. (Also there is no mention of "outdoor" or "weather resistant" much less "marine" in the Hawking literature. )

Beam width is the angle between the points either side of the axis of maximum signal where the signal drops by half (3db). The typical 8.5db omnidirectional marine antenna has a vertical beam width of about 15 degrees so when the boat heels by 7.5 degrees the signal drops by half. That is acceptable for a mono at anchor. A 12db omni has a beam width of about 7 degrees so a cat being more stable can use the higher gain.

That said a drop of 3 or 4 db will hardly be noticeable unless you are really trying to push out to the maximum range.

Given those limits there are 3 ways to increase range:
#1 get the antenna higher.
#2 increase the power of the access point/router
#3 use the shortest possible length of low loss coaxial cable.

There have been improvements in equipment over the last few years but I have found the most cost effective and simplest permanent installation that gives extended range wifi to any laptop on the boat (and any other boat within about 200' for that matter) is still the Engenius EOC-3220 EXT mounted at the masthead and configured as a repeater with a short length of LMR-200 coax to an 8.5db (mono hull) or 12db (cat) omnidirectional antenna mounted on the crane at least 6" away from the VHF antenna.

That will give theoretically you a range of about 3 miles at 12mbps to a properly installed commercial marine access point and about 1500 yards to a typical residential access point. (It will, however add about 3 pounds at the masthead reducing righting moment by a couple hunderd pounds.)

Control is provided by a gel filled direct burial CAT5 cable run down the mast to a computer at the nav station. Once a shore side connection is made the CAT5 can be unplugged and the wifi adapter turned on.

The other way to set it up would be as a bridge to a wired or wireless local network. This will give slightly more apparent speed and much more flexibility but at the expense of considerably more complexity.

20-03-2009, 05:05	#53
Gashmore Registered User Join Date: Jul 2008 Posts: 94	That Hawking corner antenna would work for a marina queen but is pretty well useless if the boat actually goes somewhere. There are two ways to increase gain with an antenna. Make it directional or flatten the doughnut. Making it directional is not the way to do it in a mobile installation. (Also there is no mention of "outdoor" or "weather resistant" much less "marine" in the Hawking literature. ) Beam width is the angle between the points either side of the axis of maximum signal where the signal drops by half (3db). The typical 8.5db omnidirectional marine antenna has a vertical beam width of about 15 degrees so when the boat heels by 7.5 degrees the signal drops by half. That is acceptable for a mono at anchor. A 12db omni has a beam width of about 7 degrees so a cat being more stable can use the higher gain. That said a drop of 3 or 4 db will hardly be noticeable unless you are really trying to push out to the maximum range. Given those limits there are 3 ways to increase range: #1 get the antenna higher. #2 increase the power of the access point/router #3 use the shortest possible length of low loss coaxial cable. There have been improvements in equipment over the last few years but I have found the most cost effective and simplest permanent installation that gives extended range wifi to any laptop on the boat (and any other boat within about 200' for that matter) is still the Engenius EOC-3220 EXT mounted at the masthead and configured as a repeater with a short length of LMR-200 coax to an 8.5db (mono hull) or 12db (cat) omnidirectional antenna mounted on the crane at least 6" away from the VHF antenna. That will give theoretically you a range of about 3 miles at 12mbps to a properly installed commercial marine access point and about 1500 yards to a typical residential access point. (It will, however add about 3 pounds at the masthead reducing righting moment by a couple hunderd pounds.) Control is provided by a gel filled direct burial CAT5 cable run down the mast to a computer at the nav station. Once a shore side connection is made the CAT5 can be unplugged and the wifi adapter turned on. The other way to set it up would be as a bridge to a wired or wireless local network. This will give slightly more apparent speed and much more flexibility but at the expense of considerably more complexity.