Wiring help

[bcreese]

Hi guys,

I had it all planned out how I was going to wire up my 1-72nd scale type 45, but now doubt has set in! This is what I have.
2 x torpedo 800 motors
2 x esc viper 25
2 x 12v 7ah batteries
2 x props and shafts
1 x steering servo
1 x 5 ch radio

I was going to wire the batteries in parallel, but the model shop said they wouldn't recommend it because one battery can charge the other and they could over heat, so now I'm stumped!:-( Also because of the size of the boat I was think of adding a 3rd 12v battery for ballast and extra running time. Any help would be appreciated or a wiring diagram.

Thanks,
Ben