Any lingering doubt they had about completing their mission disappeared when the cub made eye contact with Lakanin. He could see the desperation and fear there. The conditions were making this rescue mission extremely difficult. The water had made the fur of the cubs extremely slippery.
A combination of wet fur and tired limbs made any attempt to pull or haul the cubs in over the side fruitless. They had to find another way, and they didn't have very long to do it in.