This is proving to be a very interesting discussion. I have two steam tugs, one has the full cheddar automatic boiler control system (ABC) the second tug has no controls other than a sight glass and safety valve. The ABC works well using the pressure/temp sensor to control the gas supply (full flame or pilot flame), the optical sensor on the sight glass controls a by pass valve so the engine driven pumps are either filling the boiler or pumping water round a loop to and from the onboard tanks. There is also a low water warning for the on board tanks. The second tug is new to me and certainly makes me nervous in its use - it has a disposable gas tank so the gas will not run out before the water so I use the cheap stop watch method and bring it in after about 12 mins. I wish to add controls so am looking first to add a servo controlled gas shut off so in the event of unforeseen circumstances the gas can be shut off, next gas control, either mechanical or electrical to manage the flame so as to use both steam and gas more efficiently to achieve longer running times. A few months I also began investigating the use of cross over tech from drones, and see great possibilities for the use of cameras, gps and other telemetry. But first need to address the basic issues of making sure I do not end up with a stranded boat that has an uncontrolled flame in the boiler.