Turn the boat around and carefully pull alongside the victim, approaching the victim from downwind. Stop the engine. Pull the victim onboard over the stern, keeping the weight in the boat balanced. Use the ladder or swim platform on larger boats. Climb up the outboard if the weight in your boat is distributed correctly.
Small boats require more planning.
If you cannot reboard, stay with the boat and wait for rescue . Hanging on to the boat will save you from using energy. With luck there are boaters nearby who can assist you. If you filed a float plan, someone will notice when you are missing. Remember, most accidents are preventable.