I agree 100%.
I find value in a multi-tasker and the Ipad is that hands down. Email, weather, charts, entertainment, real GPS (not cell phone gps), etc, etc,,,,,,,
You can get a grib file reader for between $2 and $20 depending on how many bells and whistles you want, which can download weather forcasts and keep them on the Ipad while offline. You will need to be within range of a cell signal when you download, but they do travel much further over water than land.
The only ongoing expense is a data plan and I would recommend the lowest plan available, unless you can't resist downloading music, videos or whatever else eats up bandwidth. To date, I have the lowest plan and use my Ipad on the 3G network very frequently and have yet to eat up more than 30% of my allocation.
Finally, get a waterproof case for another $20.