am I planning this correctly?

Just wanted a check from some of you guys that know infinitely more than myself. I am looking to power my two tower speakers (Wet Sounds Pro 60s) and a sub (Wet sounds XS 10 FA). I am looking at using a single 5 channel amplifier to do this (Phoenix Gold R9). I would bridge 2 channels per tower speaker and then the sub. The amp says that it bridged output would be RMS 150w x 2 + 250W x 1. that matches up exactly to my speaker specs.

Question is, if I bridge the two tower speakers that takes up 4 of the channels (if I understand correctly). Would I not be able to bridge the Sub? The Amp says that its bridged power is as I stated above. The unbridged power is 50w x 4 + 150w x 1. All of this in every configuration is at 4 ohms. Am I understanding this incorrectly or does this match up.

one addition, sorry: I am going to power the boat with a blue optima starting battery and one deep cycle battery for the amp etc. I would like to get a hold of the Oddysey batteries but can't find them around here. Thanks again