Radio Help!

Just got the boat out of storage and had it winterized. When I turned the radio on w/out the engine running, its fine. But when I turn the engine on, you hear the engine noise come through the tower speakers. The Boat shop hooked my wires back up to the batteries. Does anybody know if any certain wires should not touch around the battery. It's a simple system. The radio powers the stock boat speakers, and one amp powers the sub & tower speakers. Any help is appreciated. Thanks