Sinkers and Sounders and Free Surface Effect, oh my

[from the vaults, 2007]

April 11

EOIT (Engineer Officer in Training) LTJG Josh Depietro says fueling the Munro is like playing chess, or maybe like driving with someone else’s hands over your eyes.

LT Todd Raybon and LTJG Josh Dipietro

We have 22 storage tanks holding 200,000 gallons, with three service tanks. We have other tanks, too, like a 3000-gallon overflow tank, a tank for helo gas, and a tank for fuel to the turbine that backs up our generators. Josh is our fueling officer. He works for EO LT Todd Raybon.

The fuel goes from the storage tank to the service tank to the engine with stops for filtering along the way. All 21 tanks are connected in many different ways, and we will be filling one large tank while we have three other small tanks set up to catch any overfill and then fill up themselves.

There are gauges that tell us when the tanks are full, but the only way to be really sure is to take soundings, drop a sinker attached to a metal tape into each tank. The tape is coated with a pink paste, and when it’s hauled back up, where it stops being wet is how full the tank is. See photos of sinker, sounding and sounder.

sounder sounding sinker

“These boats were all about hydrodynamics and endurance when they were designed,” Josh says, and they just stuck fuel tanks inside the hull where they would fit. It took Josh two full years on the Munro to get the fueling process down, and now he’s teaching it to ENS Gary Kim before off he goes to MIT for his graduate degree. See photo of Gary standing watch down in main control.

ENS Gary Kim on watch

Liquids in balance are the essence of stability for the ship. If you have a tank improperly loaded, the liquid inside can slosh around. This produces what is called a free surface effect which can capsize the ship. Read Blindfold Game, where I do just that.

So every day the EO sends the Captain a “Liquid Load Status Sheet,” where our 22 fuel tanks are listed by tag number and show fuel in feet and inches (from the soundings) and gallons (gauges). Also listed is status for aviation fuel and water. Also listed is how much water we made that day, our fuel consumption (days underway, total gallons burnt, daily average, and percentage used today). There is also a List & Trim page, which measures our current draft up and down the hull, the ship’s system weight and center, and its hydrostatic properties, all of which are affected by how much liquid we have on board and where it’s stowed.

The FOWK, or Fuel Oil and Water King, minds Munro’s liquids on a daily basis. It’s my favorite job title so far on board Munro, I think it’s better than Captain. Our FOWK is MK1 Don Thorpe. The aforementioned sounders work for him.

We survive out here on fuel. It runs our engines, it makes the electricity which lets us cook and flush the toilets, it burns our garbage. It’s the lifeblood of the ship.

Click here to order a copy.


Dana View All →

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6 Comments Leave a comment

  1. Thanks Dana! FA Ryan Foster (my son) was the sounder in the picture you posted. It was great to see his smiling face. What a blessing your blogsite is. There are 10-20 friends and family of Ryan that log on and read everyday. When asked what he is up to I just refer people to the site. Thanks for the insight and adventure into the Munro and it’s crew.

  2. It’s not a one-sided pleasure, Joni, believe me, I am having the time of my life. If I were eighteen again I’d be hammering on the door of the CG recruiter’s office. And thank you!

  3. Just finished Prepared for Rage, and thoroughly enjoyed it. Looking forward to the next Kate Shugak too.

    Just two comments on PFR – there’s a small anachronism in that Shuttle launches of communications satellites were discontinued following Challenger. Perhaps a bit more serious, the Shuttle launch would have been held until the freighter was removed from the security area – you just sort of dropped the freighter once Isa and his men were aboard Mun 1.

    Anyway, still a good story, and richer for the detail and your obvious admiration for the Coasties, which I share.

  4. Thanks for the comments, Pete. Glad you enjoyed the book even if it did have goobers. Which, let’s face it, all of them do whether sharp-eyed fans find them or not!

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