This would actually be a significant unit for the early industrial era. Before the advent of submarines, torpedo boats were the bugaboo of the battleship captains. A small, fast, light boat with a couple of torpedoes could slip in under the battleship's big guns and sink it with a well-placed torpedo.
If you've ever wondered just why a battleship would need side batteries of 5-inch guns, they were to defend against torpedo boats. And the vessel we know as a "destroyer" was actually designed as a "torpedo boat destroyer" -- a more maneuverable yet well-armed vessel to protect the big ships from torpedo boats.
Could be interesting if you're designing a scenario with a lot of industrial-age action. Make them available with Combustion. Cheaper and faster than submarines, but they're less powerful on the attack and can't hide under water.