Well, once we get into an era when we've got access to aircraft, boarding actions certainly become possible. Anyone recall the Crimson Skies boarding tactic? Load a bunch of guys onto the wings of an aircraft, fly slowly above the target, and have the boarders essentially jump off with mini-'chutes.
Whether it's at all intelligent to do so above a moving, shooting combat vessel rather than a slow zepplin is an entirely different question. But I can totally see somebody trying it at some point.
As to literal "point defense", Maxim guns should be available at this time (predating the discovery of electroid - if I'm not mistaken - in 1884). A point defense network of machine guns as an anti-aircraft and anti-torpedo measure sounds within the realm of possibility.