People are willing to use and iPhone that cost as much as a good handheld GPS and is about as waterproof as a sheet of notebook paper
It costs half as much as a GPS with charts, it costs 1/4 as much as a GPS with even remotely comparable charts. Also you can browse the internet, make a call, and listen to your tunes...And as for it being "waterproof", don't drop it in the water, simple as that. Or spend $30 for a waterproof case.
Technology, old farts, embrace it.