[Mixtape]

This is doubled by the fact that lots of boaters will try to keep their phone as far from the water as possible for safety's sake. In practice, using your phone is better than using nothing at all, but a dedicated waterproof device that you can clip onto your clothes and forget about is by far the better option.

[tempestn]

Most phones these days are pretty water resistant, so you could just keep it in your pocket.

[mcv]

More importantly, if you fall overboard, the value of your phone is probably the least of your worries.