WiFi was never intended to provide wide area coverage to ports and marinas. It is intended for local conectivity in your home or small office. The fact that it works at all in these hotspot marinas is a miracle in itself.
The biggest problem with WiFi is interference from adjacent Wifi networks.
The frequency channels assigned to WiFi are actually overlapping, so if you have several WiFi systems in an area, they could all be interfering with each other to some degree. Channels 1, 6 and 11 are non-overlapping and generally the preferred channels to use. If you see other channels in use in your area, some systems will be degraded.
Howard [ Just Imagine ] 22-Mar-2008
Linksys WAP as High Gain Wifi Receiver (Internet)
Linksys WAP with DD-WRT software
The early Linksys Wireless access points (WAP) came out with Linux software, and Linux software is provided under the free GNU license
which means it can be distributed freely at no cost.
So, this allowed some clever people to make some modifications to the software that enables the WAP to be used in ways that were not first intended.
It can be used as a receiver(client) using external antennas or as a relay using a receive antenna and a transmit antenna. So you could have a high gain antenna panel receiving the distant signal and then a smaller antenna retransmitting to your laptop(s) on the boat. Or you can simply plug the ethernet or USB cable into the laptop.
The high gain antenna and the receiver (WRT54) could be installed several feet above the deck and an ethernet cable run down to your laptop.
There are several versions of Linksys Wireless Access points and some of the more recent ones do not have the memory capacity to run the special software. I believe the WRT-54L is the most recent version that is specially engineered with more memory for this purpose, but bear in mind that this is all very experimental and you could end up with a dead (the guru's call it "bricked") $60 WAP that cannot be revived.
There is a wealth of information out there on the internet and free software. Just search on DD-WRT and research it carefully. One link is www.dd-wrt.com
.Howard [ Just Imagine ] 22-Mar-2008
The Cantenna (Internet)
The Cantenna is a higher gain, directional Wifi antenna that one can construct out of the right shaped empty tin can with some high quality connectors and cables.
To use this you need to have a PCMCIA Wifi card that has an antenna connection, like the ORiNOCO or Buffalo cards.
You can find more information on constructing your own here
I purchased mine off the internet for about $20 complete with tripod and cable from eBay.
The cantenna certainly does seem to make a difference. My connection with the cantenna stayed up while others around me failed.
The cantenna is directional which means you have to point it directly at the source of WiFi access which makes it a little difficult to set up and a problem when swinging at anchor. If you are going to be stationary in a marina for a while, it is definite advantage especially when you are competing for bandwidth among other cruisers using the system, and if there are other WiFi systems on nearby frequencies conflicting.
I think that the biggest advantage of the Cantenna is that it cuts out interfering signals coming from other networks and boats around the marina.Howard [ Just Imagine ] 22-Mar-2008