Someone was looking for rugged mobile laptops for their boats not long ago.

I stumbled, as I do a lot, onto this article about ruggedized mobile TABLET
PC's you may find more interesting than the foldup laptop for NAV and
control applications.

http://www.wirelessworkforceonline.c...hResults.aspx?
keyword=mobiletabletpc&TabIndex=0&image1.x=28&imag e1.y=17

These tablets are designed for workforce use, such as sales force on the
road, warehouse uses, etc.

Some with touchscreens instead of the usual touchpad or mouse, would be
great for waypointing directly in the charts themselves.

If you're looking for on-the-cheap, don't even click it. Nothing is free.