The Coast Guard Office of Investigations and Analysis has released Marine Safety Alert 04-23 to highlight the importance of proper maintenance and adherence to manufacturer’s recommendations for filling/inflating buoyancy chambers on some models of inflatable boats.

During a recent investigation of an incident that involved foreign cruise vessel operations in the Antarctic, a U.S. passenger was severely injured due to a Zodiac Milpro model FC 580/MK5 keel bladder failure while underway on a sightseeing excursion. In calm weather, the keel bladder suddenly ruptured, sending the passenger several feet into the air before landing on the deck. The passenger sustained serious injuries including a fractured femur. Another passenger was thrown overboard into the freezing water, risking hypothermia.

Coast Guard photos

An investigation showed that the keel bladder suffered a rupture due to excessive pressure in the tube. The recommended operating pressure by the manufacturer is 3.4 lbs. per square inch (p.s.i) or 240 millibar pressure (mb). An on-scene survey of multiple inflatables on board the cruise ship noted pressures up to and exceeding 9 p.s.i. (620 mb) in other keel bladders. The keel bladder is not protected by a safety relief valve, and the manufacturer recommends that they be inflated with a foot pump to reduce the chance of overpressurization. However, crewmembers were routinely using an air compressor to fill the buoyancy chambers (including the keel tube) prior to the incident. In addition, pressure levels were not being checked using a manometer as recommended by the manufacturer.

The Coast Guard strongly recommends that operators of cruise ships and other companies that use inflatable boats:

  • Review all manufacturer recommendations for inflatable boat filling and maintenance to verify those procedures are being followed prior to any boat operations including
    passenger excursions.
  • Use manufacturer recommended inflation devices (e.g., a foot pump) and appropriate pressure measurement tools to avoid overpressurization.
  • Verify that company policy addresses manufacturer recommendations and that crews are properly trained before operating and performing maintenance on inflatable boats.
  • Contact the manufacturer of your inflatable boats for any additional recommendations and/or training options they may offer.

This Safety Alert is provided for information purposes only and does not relieve any domestic or international safety, operational, or material requirement. Developed by Activities Europe and distributed by the Office of Investigations and Analysis. Please address questions to [email protected]