One type of vessel that has intrigued me is the massive yakatabune, boats used for pleasure gatherings on the river. They have a solid superstructure with heavy supporting posts and cross timbers, usually decorated with lanterns bearing the names of the restaurants that had dispatched them, and are often shown with smaller craft alongside used to ferry patrons or cook the food. … What is unusual, though, is the notch at the tip of the stempost. These vessels almost always have an extra protrusion at the end.
If the mystery ended there I could chalk it up to simply the convention for the yakatabune – perhaps just aesthetic, perhaps for whatever reason just an additional visual cue to the boat’s purpose. On a model of a similar ship in Tokyo’s maritime museum (Fune no Kagakukan), though, the stempost is apparently made of two separate pieces of wood scarfed together with a notch exactly like the tip of the stemposts in the prints. It is as though the boats shown in the prints had removed that extra piece of wood, leaving the uneven notch exposed. … If anyone has any thoughts or suggestions to help solve this mystery, I would be most grateful to hear them!
Go to her project journal for the proper illustrations (the ones here are just some that I found on Flickr) and more detail.
My theory? I think the stem, because of its size, was removable. So when it might block the view of patrons, as in a fireworks-viewing trip, it was taken off the vessel, but when it was a pleasure cruise in which the patrons were more focused on the activity inside, it was left on for elegance.