Hans, a waterproof phone is no good if its simply going to sink to the bottom of the river or the bay.

I tether my phone to a foot long foam roll "floatie", and it has saved my a$$ twice.

I used to just hang it on the rod holder atop my main motor, but more recently I slip the phone inside my Grunden bibs and let the floatie hang on the outside. When the phone rings, I just grab the floatie and the phone slide out with struggling with zippered pockets when hands are cold and wet.