I've already written the greatest good that I think about waterproof cases iPad Case by Andres Industrie (¹). It remains for me the top of the protection in all weather conditions, at sea and ashore. Bulky and quite expensive, certainly, but added to the cost of an iPad will always remain 3 to 5 times cheaper than a chartplotter for navigation, therefore useless for anything else. iPad, itself, continue to serve you home, and prepare future trips.
I can not resist the urge to spread this video by Dominique Gauthier during our trip to the Balearic this summer. For iPadNav not only sell accessories, he tests it ! Used as test our many tablets taken on board for three weeks cruise, No worry !