Abstract: A method and apparatus for reducing heat stress in firefighters supplies pressurized cooling water at a first pressure from a hose connected to a fire main for fighting fires onboard a ship. A manifold block switches parts of the pressurized cooling water at the first pressure through on/off valves and reduces pressure of the parts of the pressurized cooling water at the first pressure to a second pressure in flow regulators. The parts of the pressurized cooling water at the second pressure are fed through feeder hoses connected to the flow regulators and are conducted from the feeder hoses through tube suits each worn by a firefighter. Heat stress is reduced for each firefighter in each tube suit by the conducted parts of pressurized cooling water at the second pressure. The feeder hoses provide cooling water through each tube suit while the firefighters fight fires and during rest periods.