The antonyms for the phrase "went aboard ship" are numerous, depending on the context. Let's first break it down to its basic parts. "Went" is the past tense of "go," so antonyms could include "stay," "remain," or "stand still." "Aboard" means on board or inside, so antonyms could be "off board" or "outside." Lastly, "ship" could be replaced with any type of transportation, such as "plane," "car," or "train." Therefore, antonyms could be "left the ship," "got off the ship," "didn't board the ship," or "stayed outside the ship.