Prepare To Snorkel!!

Stack Blown!! No Flameout!!

“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!”

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Author: Lanny

Known as the 'King of Run-on Sentences", Bill "Lanny" Lanahan served aboard the Sailfish as an Engineman from November 1971 until June, 1975. After 7 years in the Navy, Lanny spent 15 years as a Caterpillar Marine Analyst before accepting a position with the Department of the Interior working for the US Fish & Wildlife Service. Lanny retired in 2012 and currently resides at his "Mini-Wildlife Refuge" located in Middle Georgia with his wife Connie and his dog Griffin.

6 thoughts on “Prepare To Snorkel!!

  1. Rick Williams says:

    Remember well that damn snorkel induction solenoid valve by the stairs to the con on the overhead in control. Every time the sea water especially in rough seas would hit that solenoid on the induction and slam it shut and draw a vacuum through the boat sucking every brain cell towards the engine rooms. I use to hate that solenoid valve when it would stick and start chattering vacuum on, vacuum off, vacuum on, vacuum off as fast as that valve could cycle. Being an A-Ganger to this day I still for the life of me don’t know why we never changed it out, did rebuild it several times to no avail.

    1. Reggie Roe says:

      Rick,we didn’t have ant stairs by conn, it was a ladder. Maybe that should have been a qual question.
      I remember sitting on locker seat by the emergency helm and looking down the passageway aft and telling the diving officer the smoke is by sonar.

  2. Reggie Roe says:

    I remember sitting in the mess deck talk with the chief corpsman, Ronnie Slack comes and says to “Doc something’s wrong with my dick. Doc says let me see. Ronnie unzips and pulls out a blood chicken leg. The look on Doc’s face was priceless. Funniest gag I ever saw.

    1. Lanny says:

      Good memory Reggie! Certainly a story worth writing about here on the blog. I do have it posted on me and Ronnie Slack’s “Politically Incorrect” blog at:, but it might need a bit of tweaking before hitting this site.

      Update: Done! Thanks for bringing that one up Reggie!


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