I have tried the laptop, and I don't know whether it was the laptop or the environment, but it only lasted two day sails.
My plotting tool of choice is my iPad, using Navionics software. The iPad App is about $70 and all the maps are free once you have the app. To keep the iPad protected, it lives in a dry case designed for keeping maps dry from Whitworths at about $40.
This is then installed in the swing away panel as per
There are drawbacks, the screen does go out at a pre-determined interval to save battery power, but you can run it via your house battery which will keep it on. The cover I have isn't that great in full sun, so I'll be looking for another soon.
As well as the Navionics system, if you have a 3G WiFi iPad, you can surf the web and post to Tophatyachts.org whilst sailing, or download a movie to watch when you moor up for the evening. It also carries quite a lot of music and can be hooked into a stereo system if that is your desire.
I also carry the official paper charts, however haven't used them, because I've not travelled that far yet.
Having said all that, if you didn't have an iPad, a dedicated plotter would be a better alternative, depending on budget etc.
Michael