Yes, you can jump start a boat with a car. The process is similar to jump starting a car, and you will need jumper cables and another vehicle with a working battery. First, ensure that both the boat and the car are turned off. Then, attach the positive (red) cable to the positive terminal of the dead battery on the boat. Next, attach the other end of the positive cable to the positive terminal of the working battery on the car. Now do the same for the negative (black) cables, attaching one end to the negative terminal ofthe dead battery onthe boat, andthe otherendto either an earthing pointon themetalof theatomotivechassisor directlyto thenegativeterminalonofthecar'sbattery. Finally,startupthatt engineandletits idlefor awhilebeforetryingtocraneupthesails!