Round Uptakes

By Bob Cohen, Midshipman

    Poor Mr. Smith. He was the Chief Engineer of the only Knox-class frigate in the entire Pacific Fleet with round uptakes, and his career was pretty much over.

    The Knox-class, sometimes referred to as “McNamara’s Folly” after the whiz-kid Secretary of Defense whose automobile industry expertise was somehow implicated in their design, was an unusual class indeed. Although originally designated as Destroyer Escorts and later reclassified as Frigates, at well over four-hundred feet long and nearly four thousand tons displacement they were bigger than most destroyers of their era. While they were well-built, their singular quirk was a relative lack of redundancy – not exactly a minor shortcoming for a ship intended to do battle. One five-inch gun, one ASROC launcher, one helicopter… and one screw. The loss of any of these things could present a bit of a problem.

    The most recognizable feature of these ships was undoubtedly the ‘mack.’ Instead of having separate masts for the electronics and stacks for the engineering plant, the Knox-class had one enormous combined structure amidships. It looked, for lack of a better way to describe it, like a giant Dutch windmill without the blades. The huge, circular base gradually tapered as it climbed into the sky; there was a funny-looking big , flattened cylinder with rectangular exhaust uptakes plopped on top, then all the radars and antennas and stuff was piled on top of that. Having seen a Knox-class frigate, you’d never mistake it for anything else, nor mistake anything else for it.

    The ship’s engineering plant was an elegant design considering the inherent limitations. There were only two 1200-psi boilers. Since all boilers need to be taken off the line sooner or later for routine maintenance, all of these frigates were sometimes one-boiler ships. Of course, since all boilers occasionally get away from their handlers, no matter how skilled, these one-boiler ships were also potentially ‘hot, dark and quiet.’

    The designers incorporated a few interesting features to assist the crew in getting up steam in an emergency or casualty situation. The ship had a diesel generator which cranked out enough juice to go on the same electrical bus as the three steam-powered turbo generators, and that’s exactly what it would do if you lost steam. Many of the various pumps in the fire room, customarily steam-powered in other ships, were electrical on the Knox-class. That big diesel actually had a good chance of keeping the engineers’ house of cards from collapsing. If you lost everything, there was a bank of compressed nitrogen bottles to give an emergency burst of fuel-oil pressure, hopefully to make enough steam to start all over again. Still, there was an even greater-than-normal sense of urgency if you lost the plant on one of these frigates.

    Mr. Smith was tied up in Pearl Harbor one day in the late 1970s so it wasn’t really important whether he was steaming one boiler or two, but he definitely lost fires in one. A 1200-pound boiler looks like a big silver barn, and on one side, you’ve got all the burners. Despite the relative sophistication the basic teakettle analogy still applies – but instead of burners on a kitchen stove firing up, boiler burners are firing in – to cook that water into steam. Just like a stove burner though, if the fire goes out for whatever reason, the gas keeps going until someone realizes it and turns it off. Unless you actually saw the fires go out it was pretty much anyone’s guess as to exactly how much liquid fuel oil was sprayed into the firebox. And if the boiler had been steaming for any length of time, the firebox was hot.

    To be sure, that fuel oil didn’t just sit in a puddle in the bottom of Mr. Smith’s boiler. It immediately started to vaporize from the intense heat. In order to prevent the boiler from becoming an internal combustion engine there were specific ‘purging’ guidelines to be followed prior to attempting to light off again. Mr. Smith followed these guidelines since he really wasn’t in a hurry. After all, he was inport. Forced-draft blowers on max for the requisite amount of time, the nasty fuel vapor was expelled from the furnace, right out through the uptakes. Nice and easy. They made ready the burnerman’s torch. No rush. They lit it with somebody’s zippo, and at the Chief Engineer’s direction, the burnerman shoved the flaming torch into the little hole in the side of the barn. And the residual fuel oil puddled at the bottom of the 2 boiler, patiently vaporizing since they stopped the purge, reacted as one might expect upon its introduction to fire. They said you could hear the explosion on Molokai. Thankfully, no one was killed, but the blast bulged the frigate’s rectangular sheet-metal uptake turning into something much less angular.

    The Navy ripped Mr. Smith’s buttons from his choker whites and busted his sword for good measure. Then, they developed something known as a ‘Boiler Inspection Device.’ This seemingly high-tech gadget was really nothing more than a long periscope with a flashlight at the end. The plan was simple: in the event of a loss of fires, after the required blower purge the BID would be stuck into the boiler through the torch hole and a very thorough visual inspection of the boiler’s innards would be made prior to inserting the torch, just in case there were any other puddles of fuel not familiar with the Navy’s purge tables. This device, apparently very well-made of the finest stainless steel, was not well received. I asked a grumbling BT Chief why he was resisting such an obvious technical triumph, and he showed me the business end of the BID – a blazingly bright halogen lamp – which got blazingly hot after a few minutes of operation. “About as hot as the torch,” he muttered under his breath.


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