Multi switcher, not a common item, so they tend to hide beneath the radar a bit. There is one here
http://www.electriflite.co.uk/store/...p/tr-rcs7.html that might do the job/explain things. If you google for rc switchers, most of the information is for DIY ones, probably because of the small commerial market for them.
Works well, but the instructions do need reading. Have a look round that site, as Dave is a long time modeler, there is plenty of good information in fairly plain English on there.
The water being pumped on 12"/foot ships is usually cooling water for whatever is running, any small pump should do. Again, since it is a small market, you might have to do your own electronicery to get it working as you want it. Fire cannons basically need a screen washer pump and a switcher with big enough contacts to do the job, or a relay worked by one of the channels of the multi switcher.