Answer: By Bike
Step-by-step explanation:
In the book, The Cay by Theodore Taylor, Phillip and his mother are attempting to go back to the US aboard the S S Hato when a German torpedo sinks the ship causing a shipwreck on a derserted island for Phillip where he met Timothy.
The book exains Tankers in aittle detail and mentions that Tankers were so big that to move around one needed a bike to do so.