How the NATO study MASHIEN will reduce injuries at sea

Nordic Defence Sector has interviewed anaesthesiologist and researcher Johan Ullman, who leads the NATO project MASHIEN. The study examines how shock exposure aboard high-speed vessels affects crew combat effectiveness and health. The results are intended to form the basis for a common standard to prevent serious skeletal and brain injuries in operators.

Johan Ullman is a reserve officer and physician. As a flotilla medical officer in the 1st Surface Attack Flotilla in 1984, he observed the effects of shock exposure aboard high-speed vessels.

"I was tasked with conducting medical fitness assessments of conscripts from the torpedo boat divisions, and found to my dismay that 85 per cent had developed back pain from serving aboard during their military service. They said it made no difference whether you sat or stood, it was simply extremely painful when the boats slammed into the waves," Ullman told NDS.

That insight prompted him to begin researching the actual mechanics and nature of the exposure. Historically, measurements at sea have focused on vibration, which he argues is fundamentally incorrect when assessing the risk of serious injury.

"There was no real knowledge in this area. Most of those who have previously researched this have not understood the physics behind how much energy a shock contains and how extremely rapidly that energy is transferred to the human body," he says.

To understand the true risk of injury, the concept of "jerk" is central. It describes how rapidly acceleration changes. A powerful acceleration that builds up over time affects the entire body uniformly, whereas a sudden and severe shock has entirely different consequences.

"If acceleration goes from 0 to 10 g in ten milliseconds, it produces a far higher mechanical effect than if it takes 50 or 100 milliseconds. A jolt that goes straight to maximum immediately and then subsides affects the body's various organs in different ways. This is because the stopping time is so much shorter. It is this type of exposure that causes personnel to destroy their backs and necks," Ullman explains.

To map the problems and establish threshold values, he now leads a research group within the NATO Science and Technology Organisation (STO). NDS has previously published a piece by John-Mikal Størdal, head of the STO Collaboration Support Office (CSO). The study Ullman leads is named MASHIEN and involves a total of 34 researchers from 15 different countries. The project is funded primarily by the Swedish Armed Forces (Försvarsmakten) through research and technology development funding.

"Every person, every wave, and every hull slam is different. We need large amounts of data and must take measurements on the vessels out in real conditions. Two crew members per vessel wear accelerometers attached close to the iliac crest, measuring in three axes at 5,700 measurement points per second per vessel for analysis."

Ullman notes that a well-known problem in the naval environment is the under-reporting of symptoms. Personnel frequently avoid seeking medical attention at their unit out of fear of losing their flight or sea status and instead being assigned to a desk role. To obtain objective data, the technical measurements are now combined with daily, anonymous information collection from operators.

"Once a day, participants receive a notification on their mobile phone. They are asked to indicate whether they are in pain, where the pain is located, and to use a slider to rate the intensity on a scale, as well as whether they have been on a vessel and, if so, which vessel. By matching the reported pain with the measured exposure, we can correlate which specific shock levels lead to problems," says Ullman.

Previously, the focus was almost exclusively on musculoskeletal problems, but in recent years awareness has grown that the shocks also cause serious neurological and cognitive injuries. An internal survey directed at retired American operators found that 33 per cent had experienced loss of consciousness as a result of whole-body shocks aboard vessels.

"It is not only a matter of herniated discs and vertebral compression fractures, but now also of brain injuries. When the vessel slams into the water and the body is forced downwards, the head is flung forward with enormous force. The brain shakes inside the skull, and the rotation causes injuries similar to those seen in retired professional boxers or American football players, known as CTE (chronic traumatic encephalopathy)."

The severity of the cognitive injuries became major news when an American boat operator took his own life and the New York Times published an article about the case in 2024. The post-mortem examination revealed that his brain was deeply permeated by cumulative damage linked to his service.

"It began with him making poor judgements and being medically retired. It was incorrectly assumed to be a psychiatric condition. When the autopsy subsequently confirmed extreme CTE, it gained significant momentum in the United States. It led to Senate hearings and resulted in several American researchers joining our study," Ullman recounts. "Since then, a further dozen have come on board."

Within the study, 15 countries have agreed on a new method for measuring and quantifying shock exposure. The results will be used to provide operators with relevant real-time information, specific to each vessel type, indicating when exposure is approaching or reaching presumed harmful levels.

Concerns have been raised that stricter safety regulations could force speeds down and reduce operational capability, but this view is firmly rejected.

"This will not limit capability. On the contrary. There will be a display on each vessel indicating shock exposure in green, yellow, or red. The operator then receives direct, objective information and can adjust speed according to the task at hand. If it is necessary to move faster, for example under fire, that remains possible. In the long run, however, this reduces unnecessary and harmful exposure, and units maintain their combat effectiveness and operational capability," Ullman concludes.