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Air-Locked Diesels?

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Following Up on Megayacht Yogi Sinking - by Capt. Bill Pike

Then there’s the controversy over the reason for the starboard engine’s overheating, the event that seems to have triggered a chain of events ultimately leading to Yogi’s demise. Without bothering to explain why, the French report simply dismisses what Yogi’s captain reportedly told a Proteksan-Turquoise representative during a brief cell-phone conversation immediately following the rescue—that the cause of the overheating of the starboard engine was most likely “air that blocked the cooling water to the sea strainer,” a problem that predictably results from excessive pitching and rolling at rousing speeds in heavy seas. 

Instead, the report suggests that Yogi’s sea strainers (which apparently had been working nicely since her launch almost a year before) began restricting water flow on the night before the sinking due to improperly designed strainer baskets, a theory apparently endorsed by the crew during interviews that took place in France well after both the sinking and the captain’s cell-phone call.

“I strongly disagree with this,” says Richard Boggs, a U.S. Merchant Marine Unlimited Chief Engineer with a strong background in maritime education and safety training. “My take on this thing is just what the captain reportedly told the builder to begin with—the vessel’s rolling allowed air to enter the main-engine raw-water cooling system and ‘air-locked’ one or both systems. They had to shut down one engine because of an exhaust connection failure that was most likely caused by an air-lock and the other engine shut down automatically due to high temperature, almost certainly caused by an air-lock. Things went downhill from there.”

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