Stay on the boat!
Tethers are a pain. When you need to move quickly, they foul or pull up short. If you fall over on the fore deck they will stop you at the first stanchion. If you are on the high side you can kiss it goodbye. On the low side, maybe you will be able to pull yourself back on board.Two seperate tethers is the only way to go. If single handing, you need to have an additional jack line running outside of your shrouds, along the sheer, so if you go over you can hook to this jack line - hopefully work your way aft and reboard. You need two seperate tethers to pull this off. Wear a scuba diver's knife on your ankle so you can, with one hand, cut what is needed should you go over.If you are single handing and go over, you probably are dead. Close to a shore, one may be better off falling in free of the boat and swimming to the beach. We on L Mich. lost a single hander two seasons ago. He was found tethered, over the side, to his boat when it washed ashore. You have to have a way to free yourself because, with autopilot, one can be dragged a long way. Reboarding a boat travelling 5 knots or more is probably impossible. Single handing really boils down to staying on the boat.