“I’ll never forget the sounds, smells, and vacuums that took place during a good snorkel run, but what will always stick with me was being the Throttleman on watch and having the responsibility for making sure there wasn’t a ‘Flame-Out’ when firing up one of the main engines and blowing the stack!!”
The one thing that always got my adrenaline pumping was when the order to “Prepare to Snorkel” was given. The greatest fear of any Throttleman when on watch in either of the two engine rooms on Sailfish was the possibility of having to deal with an engine ‘Flame Out’ and the possibility of salt water entering the main engine through the exhaust piping and actually flooding the engine.
Since snorkel air induction pipes were drained inboard of any water on Sailfish, the only other pipe that we were concerned with in the engine rooms was the snorkel exhaust pipe. In order to clear the snorkel exhaust pipe, one of the main engines – typically one of the more reliable and stronger ones – would be used to perform the duty of ‘Blowing the stack’.
The process on Sailfish was a coordinated effort between the Engine Room Throttleman and his Oiler. The Throttleman was responsible for starting the main while the oiler was responsible for manually opening the engine exhaust valve when the Throttleman gave the nod – typically at the point when the main just started to fire up. The next step was for the Thottleman to open the snorkel exhaust valve which was done by toggling a switch on the Engine Room Control Board. Opening that particular valve was done when the running engine reached a specific level of exhaust ‘Back pressure’. If performed correctly, the engine exhaust gas pressure would overcome the water pressure within the snorkel exhaust pipe and ‘blow’ the water out of the pipe which was typically at or just under the waters surface.
If done incorrectly and the main engine stalls and dies – typically a result of opening the snorkel exhaust valve before sufficient back pressure was achieved – it was referred to as a ‘Flame-Out’ – something NO Throttleman (or ANYONE in the Engineman Gang) wanted to deal with – especially face to face with the Chief Engineman and the Engineering Officer since it typically resulted in a thorough internal engine inspection.
Also, if too much engine back pressure is built before opening the snorkel exhaust valve, the engine exhaust manifold relief valves on the side of the engine would blow open and fill the engine room with exhaust smoke causing a ‘Smoke-Out’ – another dreaded embarrassment but not as severe as a ‘Flame-Out’.
I’ll never forget the sounds the main engine would make when blowing the stack. If all went as it should, you could hear the engine load up and labor a bit just before the stack was blown, and then a second or two later settle down to a gentle 800 – 850 RPM no load speed before shifting engine controls over to the Controllermen in the Maneuvering Room in order to commence a battery charge.
“What a RUSH!”