I think its just stoking the boilers. When coal powered ships need to increase steam pressure they need to burn more fuel and until the fuel is properly burning coal produces huge amounts of smoke. This is why sometimes you see lots of smoke and other times really not too much depending on what they are doing, working up to full speed makes more smoke than keeping there.
Nick, I think you will have to make the steam pinnaces as she will look empty without them, and people will ask!
In general my understanding would be that they would land most of the lighter boats when going into action as there is no way they can survive and you are just taking splinters and a fire hazard with you. Its a little unclear and I have yet to find definitive proof either way. If you look at the high lift cutters on the mainmast they are too exposed to gun blast and in the way of the aft conning tower so would bet they would be landed before action, or possible cast adrift before action. This was frequently done in the days of sail, they would use a sea anchor to hold them and find them afterwards. If you won you can find them, if you lost it didn't matter!
Keep up the good work
Cheers
Geoff