Ahoy there, Daniel! Indeed, Big Gun does allow torpedo-boats. MTBs (motor-torpedo boats), PT boats, and German Schnellbooten are all too small to be built in scale (I had a hard time with a twice-scale model, not for combat). However, destroyers and fast light cruisers fill the same role exceptionally well. Boats like the USS Atlanta, RM Capitani Romani, and DKM SP-1 Spahkreuzer all make amazing heavy "torpedo-boat" cruisers, with battleship-busting firepower and the speed and maneuverability to deliver their ordnance on target with incredible precision. To counteract that threat, we use smaller, faster, even more maneuverable "torpedo-boat destroyers" that can chase down and sink those large torpedo-boats. I personally sail the German destroyer Z-25, as fine a torpedo-boat destroyer as ever there was. Other ships like FN Le Fantasque and USS Gearing fill the same role. Check out some footage of Big Gun "torpedo-boat" cruisers in action Turn-of-the-century torpedo boats are definitely on the small side, even for a destroyer. Even an elite builder would struggle to successfully put one together. But if you pick up a Le Fantasque fiberglass hull kit from Strike Models and build a set of MJV-2 torpedo cannons, you can have a fighting boat ready for combat in just a few months of weekly weekend build sessions. If you have your heart set on an early-period boat, find yourself an experienced local combat shipbuilder and we can talk about a few early-period designs that I've been planning.
Here is a link to Clark von Tugboat's build thread of an Orfey class Imperial Russian destroyer. Othar This size vessel is very tricky as I can attest to in my attempts (as yet unsuccessful) to do a Clemson class destroyer, but with recent advances in battery and motor technology they are becoming more attainable.
Othar WILL be running in campaign at Nats. At least one run with a spurt gun. Note that the pump and controls will not be removed for Nats operations, just disconnected from the receiver (to be legal). Since I'm proposing a rule to make it legal, I want to prove in combat that it's doable to build and operate a 1/2 unit warship with a gun and a pump