According to Minta Durfee, Roscoe Arbuckle's first wife (& also his wife in the film), the boat filling with water was Arbuckle's idea and was intended to be a practical joke on Charlie because of his aversion to it. In Kevin Brownlow's The Parade's Gone By, Minta is quoted as saying: "Charlie hated water...And later on, he and my husband did one of the most difficult things an actor can do: in the last scene they lay in a boat, pretending to be dead drunk, while it slowly sank in the middle of Echo Park Lake. For a man who hates water, that was pretty good.”
Charlie must have been a good sport because he appears to be unable to keep a straight face as they disappear beneath the surface.
However I find the notion that Charlie was afraid of water interesting because he enjoyed swimming most of his life and gets wet in several other films including A Film Johnnie, The Masquerader (which was released only a couple of weeks before this film), Shanghaied, A Night In The Show, The Cure, The Adventurer, City Lights, Modern Times, etc. Perhaps he didn't like to be surprised by water, which is understandable.
This post was previously published on January 3rd, 2013.