Wind speed not factored in to El Faro stability metric

Hurricane Joaquin's winds were more than twice what El Faro's stability is calculated with, but building in a higher threshold may not have made a difference.

Herbert Engineering President Spencer Schilling says they figure out a ship’s GM- a stability metric- based on factors including cargo loading plan, ship size, center of gravity, and more. Based on the ship size, they factor in a wind pressure, which in El Faro’s case equated to 50-55 knots.

Joaquin was a Category 4 when it ran in to the ship last October- meaning winds around 113-136 knots or 130-156 miles per hour.

“It might be useful information to know what kind of impact a certain wind speed has on its [the ship’s] heel, but it’s not related to stability,” Schilling says.

Schilling says, from a physics perspective, the most important information in regards to this metric is what they already measure. While you can figure out the wind speed based on the wind pressure that’s used in the calculation, the wind pressure itself is plugged in to correlate to the ship’s size- not the conditions.

“Have you done any calculations to estimate the effect on the vessel experiencing those kinds of winds on the angle of heel and required GM,” asked NTSB Investigator-In-Charge Tom Roth-Roffy.

Schilling says Herbert Engineering does not.

“In our mind, it didn’t seem much purpose in using the criteria to evaluate the effect on required GM with wind speed,” he says.

Schilling acknowledged that, if wind speed were increased, the required GM would increase, but again added that’s not the best way to calculate that. Further, he says Captains are trained to steer to mitigate the effects of the wind.

“There’s no rule that can be put in place that’s going to ensure a vessel is going to survive every condition it’s possibly going to encounter, and that’s where the complimentary part of any stability rule or ship operating rule is prudent seamanship and avoidance of heavy weather,” he says.

Herbert-ABS Software Solutions VP and Head of Development for CargoMax Michael Newton told the Coast Guard Marine Board of Investigation that he believes they would be able to add wind velocity in to the software.

He says, overall, the company is more sensitive now to how they're pushing out updates in the software. Investigators learned El Faro was using a version of CargoMax that was more updated than the one their surveyor, the American Bureau of Shipping, had approved. Newton says he didn't feel it was necessary to take the update to the surveyor to be re-approved.

FULL COVERAGE: El Faro sinking

Herbert Engineering has been involved in several redesigns on El Faro and with updating the manuals that come as a result. On average, the company updates a couple of "Trim and Stability" books every year for various ships, although Schilling says they're in the process of a massive review project covering several hundred manuals in the next few years. These booklets give basic guidelines on ship stability based on its specific design.

Schilling says a few of the redesigns they’ve done actually didn’t lead to a new set of tests, because they can rely on information from El Faro’s sister ships. There are differences, though. For example, some drawings dealing with El Faro before she had fructose tanks installed had a whited out space where her sister, the El Yunque, had fructose tanks. Schilling says that led to a discrepancy with affiliated cargo numbers, because they didn’t add the space back in as potential cargo space. That space was ultimately blocked off again in 2014, when El Faro had fructose tanks installed.

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