Same footprint; no problem, that is a single din receiver. It will fit right in the existing slot and may come with a trim piece to give it a clean look.
Wire right up; very unlikely. Your new head unit will come with a wiring harness to plug into the back of the unit. There will be wires leading into the new plug that you will need to connect to your existing wiring. You will need to know the wire colors for the positive and negative inputs for your existing speakers, and connect them to plug for the new head unit.
Crutchfield provides excellent customer service and can talk you through an installation. I'm glad to assist also.
2006 Bayliner BR205
A1 Gen 2 1.47
5.0 carb engine