Tom Gilbert of Jensen Beach, Florida, asks:
"I'm about to install Wi-Fi on my boat so I can use my laptop when I'm in the harbor. I think a 14-element YAGI, such as the RL/WAVRVMAR or the RL/14ele2.4wp, would be good units I can aim, set, and receive. However, other people tell me that an omnidirectional antenna is the answer. Which is the better mousetrap?"
Gordon West replies:
Usually there are many WiFi signals around a harbor. In fact, there may be so many signals that you'll want a directional beam antenna to get good reception. These units beam the transmit-and-receive energy in a concentrated pattern that extends out 5 degrees on either side of the antenna's centerline. If you have access to a yacht club's wireless facility, you should point the beam antenna at the white omnidirectional antenna that is probably located on the roof of the building. This will eliminate the interference coming from other systems using the same channel.
This YAGI, or beam antenna, can be either a dish or a half-dish parabola. I like the units made by MJF Enterprises (mjfenterprises.com). The specific unit I have in mind is the MJF-1800, which sells for about $25. If you want a smaller, flat-panel antenna, look at the MJF 1802, which goes for about $50. It is a good choice for mounting on a dock.
An omnidirectional antenna, on the other hand, has elements that are stacked vertically inside a radome and can receive signals from all directions. If you are moving up and down the coast, you should probably carry both types of antenna. The omnidirectional fiberglass Wi-Fi antenna SF-245W-R from NGC (natcommgroup.com) is just right for a small sailboat.