I'm not sure what the etiquette is here, so mods - delete my post if it's inappropriate.
The problem you mention is a big issue with boaters - how do you easily get shore based wireless access while also getting wireless access inside your boat. The answer to the question is that there are a few very expensive ($1,500+) devices which offer both access point capabilities inside the boat, and connectivity to shore. The alternative is to buy something like an Engenius for shore based access, hook it up to a wireless router on the inside of the boat (which are USUALLY, but not always AC powered) and that will give you what you want. You still have to deal with a big thick cable going up the mast for your antenna, or hanging something off your halyard. You will usually get signal loss if you have to run a long cable.
Anyway (and here's the part the mods may have to delete) - a friend of mine and I (we both own IT companies and met cruising) got sick of having lots of cables, high power draw, signal loss, multiple devices, etc. for the problem you describe. Instead of complaining, we're in the process of building a product. It's not available yet (we expect in 2-3 months it will be ready), but it will be a small, low power device that combines the access point and the shore system in one unit and lets you create a wireless cone of access on your boat that's always on. This will allow us to support phase two, which will be NMEA integration and an iPhone/Touch application for things like an anchor alarm, instruments, etc. Phase two is a ways down the road. Anyway - no product announcement yet, and when we have it we'll look at the costs of sponsoring Sailnet and doing things the right way.
In the meantime - mods (if you're listening) - would it be OK to post a thread asking people what they want to see in a wireless device? It's an opportunity for us to build it in to this unit and make something pretty cool for the cruising community. Or, if you need to, delete this post