When it comes to synonyms for the phrase "keeps aft," there are a few options to choose from. One option could be "stays towards the back," which has a similar meaning and conveys the same idea. Another synonym for "keeps aft" could be "remains astern," which also means to stay behind or towards the rear of a vessel. Finally, the phrase "retains aft" could also be used as a synonym for "keeps aft," as it implies the idea of holding a position towards the back of a ship or boat. Ultimately, any of these phrases could be used interchangeably to convey the same idea of staying towards the stern or back of a vessel.