While, I could use a mobile device, and IT seems enthusiatic, but I prefer a fit for purpose and dedicated tool like the Velocitek on the boat. Battery life is better, it's waterproof by design, the screen is easier to read, it's less likely to be munted when the crew (surely not) knees it or goes ballistic with a winch handle, and I know it's always going to be on the boat. There's a lot going on in the cockpit and the last thing I need is to worry about a fragile iphone or tablet sliding around on the floor or the deck because the genny sheet flipped it from its cradle.