Schroeder said when boats are docked they need to plug in to recharge batteries. While docked they also use this power to run things on the boat like lights and even air conditioning in bigger boats, which means boat need to be properly grounded. Most boats are grounded to what's called underwater gear, meaning anything that's under the boat, so the prop of the motor or other equipment, he said. That way if a boat was ever hit by lightning, or the water was electrified, the electricity travels through the boat and into the water -- not the people on the boat.