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KNRM Improves Crew Safety with Modern Shock Mitigation

Lifesaving organization refits 44 vessels with cost-effective approach
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KNRM Improves Crew Safety with Modern Shock Mitigation

If you’re Dutch, the Koninklijke Nederlandse Redding Maatschappij, or KNRM, might be a household name. For the rest of the world, the KNRM is also known as the Royal Dutch Rescue Society, and the organization dates back to 1824 when Dutch warship “De Vrede” was stranded along the Dutch coast. While ten people were rescued successfully, six of the rescuers were lost, and the indignation of the residents of Amsterdam and Rotterdam led to fundraising campaigns to establish two professional rescue organizations, now jointly known as the KNRM.

Since that fateful day, the KNRM has grown into a trusted lifesaving organization, comparable to the Royal National Lifeboat Institution in the United Kingdom and the German Maritime Search and Rescue Service. Entirely financed by private donations, the KNRM maintains over 70 vessels ranging from small boats to 21-meter Rigid Hull Inflatable Boats (RHIBs) and employs over 1300 volunteers at rescue stations staffed around the clock.

Rescue vessels are traditionally staffed by volunteers, called boarders, who don’t hesitate to head out in extreme weather conditions. It is critical that the volunteers arriving on the scene of a rescue show up fit for duty, however, nothing fatigues the human body faster than bracing for, then enduring constant wave impacts on a high-speed boat. For this reason, professional shock mitigation seating systems are an integral component within the KNRM fleet of lifesaving vessels. 

The Valentijn and Arie Visser class lifeboats had been outfitted with suspension seating upon their original commissioning as early as 1990, so KNRM planned a fleet modernization program in 2019 to ensure that the boat crews had the most technologically advanced equipment available.

Hans van der Molen, a technical specialist for the KNRM, suspected that the original, once-cutting-edge suspension seating on the lifeboats were now becoming dated technology as the shock mitigation industry advanced. 

The seats originally installed on the lifeboats specified 3 to 5 inches (80 to 120 mm) of suspension travel, but for the rough conditions that the KNRM volunteers encounter daily, it was evident that longer suspension travel was required to mitigate the risk of injury. The suspension travel that the seat reportedly offered was showing increasing probability of ‘bottoming out,’ or striking the bottom of the seat travel, which can cause immediate pain and injury to the seat occupant.

Van Der Molen set out to identify new suspension seating systems that had to both improve crew safety and fit within KNRM’s budget parameters. The challenge was that the crews had to accept the seating as comfortable enough to sit on.

Van der Molen designed a test process to determine which shock mitigating seats in the industry performed to the highest standards. The KNRM team built a test platform called a ‘sled,’ a bare-bones boat hull with nothing on it but seats bolted to the deck. A crane dropped the sled into the water at 1 to 2 meters high to measure the acceleration at the deck and on the seats. The team tested several impact mitigating seats from a range of manufacturers with this method. From this data, the research team calculated a mitigation ratio, or the difference between accelerations of the deck and seat, for each set of seats to demonstrate an apples-to-apples comparison of seat performance. The results from the testing showed that the existing suspension seats did not isolate shocks as required by KNRM. 

To stay within the project budget while still providing the crews with updated technology the team decided to replace only the suspension module underneath the seat, leaving the seat buckets intact. The original suspension modules were swapped out with SHOXS X8 shock mitigating seat mounts which provide a full 8 inches of travel, enough to withstand the roughest conditions the rescue crews would experience.

This effectively upgraded the entire lifeboat fleet without a major cost outlay, or going through the process of sourcing new seats that the crew would accept. 

Van der Molen reports that the boat crews now feel “less contact” with the boat, meaning the energy from each impact is being absorbed through the pedestal and not through the seat or their body. That, coupled with a controlled and damped rebound, makes the ride exponentially better from both a comfort and, most importantly, safety stance.