Need AMP advice...new system.

I need some advice on Sony X Plod amps. I've been searching on E bay, and there's way too many variations in watts and channels to understand what I need. This is what is being put in the boat:

Sony Xplod CDX 50, with XM
12" Sony Xplod Sub 1300 watt
two front and rear tower speaker, Sony Xplod 220 watt....880 watt total
two rear only tower speakers, 220 watt Sony Xplod
Four 6.5" interior speaker....Sony Xplod 270 watt, total of 1080 watts

So...1300 watt sub
and 2400 total watts of tower and interior speakers.

How many channels, and how many watts do I need in an amp or amps??

DC