You should know that large ships are different from small ones. When a large ship is sailing, the waves it creates on both sides can easily capsize nearby small boats. Normally, if you're rescuing someone at sea, a vessel absolutely will not start moving, because that wouldn't be a rescue but a killing.
Seeing that the ship had started, he immediately reached for the safety rope tied around him and tugged hard. After feeling the safety rope tighten, the panic at the bottom of his heart dissipated somewhat.
At that moment, he understood why Fabian had earlier moved towards their location—it was out of fear that the ship would simply sail away and leave him behind.
Samuel Jenkins, standing on the deck, sighed in relief when he saw the crew member had gotten Fabian into the life ring. He then immediately called to the others nearby to work together and pull on the safety rope, aiming to quickly haul the three in the water back onto the ship.
