What is a key method to enhance survival chances without a life jacket?

Using floating debris to help stay afloat is indeed a key method to enhance survival chances without a life jacket. Floating debris can provide essential buoyancy, allowing individuals to conserve energy and stay above water for longer periods. This technique takes advantage of readily available materials that may be found in the water after an emergency, such as parts of the vessel or any other objects that can support a person's weight.

In contrast, swimming vigorously to reach shore may not be the best strategy, especially if the distance to shore is far or if the swimmer is already fatigued from the incident. Additionally, waiting for rescue on a vessel may not be a viable option if the vessel is sinking or if help is delayed, leaving individuals in a vulnerable situation. Signaling with a flashlight, while important for attracting attention, does not aid in staying afloat or improving survival chances in the immediate scenario of being in the water without a life jacket. Hence, utilizing floating debris offers a practical and effective solution to significantly enhance the probability of survival.