Ships of the Imperial Russian Navy: 1900

[KWorld]

Only other option I can think of, in the days of coal smoke and steam and before the torpedo bomber, is a low-profile torpedo vessel that's running slowly, but either one (sub or surface) is tough to arrange: you have to engage the enemy battle line and bring them to where you want them, so they run over the slow torpedo carriers.

Agreed.  Unless you control a strategic point which the enemy needs to approach.  Which is, of course, the essence of a tactically defensive but strategically offensive strategy, take something your enemy needs to take back and bleed him dry when he attempts it.

Even then, using subs or slow surface torpedo vessels will be problematic, outside of very constrained spaces like the Dardanelles or some Norwegian fiords.  A small turn by your opponent, made to (for instance) clear the smoke from the director, will take the battle line outside torpedo range of your vessel, and there's nothing the slow vessel can do about it. 

[Darman]

This is very true.  Its best if they are surprise weapons reserved for occassions where you are sure of hitting at least one target. 

[Delta Force]

I just realized that a torpedo battleship could be used not so much to actually hit other ships (although it is certainly possible with dozens of torpedoes being fired by a single ship) as to cause the enemy line to scatter, making it easier for torpedo boats to pounce on a larger ship. It might also cause the enemy line to turn into a minefield or (once more developed) submarine ambush.

Also, how hard would it be to disguise a torpedo broadside ship as another ship to avoid it becoming a shell magnet? Could it be made to look similar to a regular armored cruiser (similar dimensions and attacking with them so it's not blatantly obvious), perhaps with dummy turrets and guns that emit pyrotechnic smoke?

[KWorld]

I just realized that a torpedo battleship could be used not so much to actually hit other ships (although it is certainly possible with dozens of torpedoes being fired by a single ship) as to cause the enemy line to scatter, making it easier for torpedo boats to pounce on a larger ship. It might also cause the enemy line to turn into a minefield or (once more developed) submarine ambush.

Of course, but the ocean's a big place, and at this time period your position's something that's dead-reckoned, unless you're close enough to shore to get a triangulated position.  So getting this sort of ambush positioning right is .... difficult.

Also, how hard would it be to disguise a torpedo broadside ship as another ship to avoid it becoming a shell magnet? Could it be made to look similar to a regular armored cruiser (similar dimensions and attacking with them so it's not blatantly obvious), perhaps with dummy turrets and guns that emit pyrotechnic smoke?

Technically, that sort of visual camouflage would be possible.  It won't take long, though, for the enemy to figure out that there are more shots being fired at us than there are splashes around us.

[Darman]

I'm sure that a demonstration of the use of torpedoes in confined sea-lanes could be arranged.... the Ottomans would like to formally invite the russians to attempt to force the straits ;)