I'm looking at getting a VHF radio for the new boat, which is better? Fixed mount or handheld? I want to go 50-100 miles offshore for fishing and don't want to get stranded without any communication.

Fixed mount will have more range, since you can mount a proper antenna. If you plan on going 50-100 miles out you need a quality fixed mount at minimum. I do, and would suggest, that you carry a handheld with your emergency gear in the event you have to abandon ship.

Fixed mount. Get a good antenna as well. Bigger is better.

I've always had both. The handheld is useful as a backup, but also can be used when ashore too and someone else is still on the boat. Some areas of Catalina don't have cell service or is crappy.

Fixed mount and invest in an EPIRB