Running upside down

The Nh 1816 is fitted out with MTU engines that keep running even if the ship overturns and re-rights itself. According to MTU, it is an application that is unique almost anywhere in the world.

Powering to safety

The Nh 1816, if she proves her worth, will replace the Koos van Messel and her Arie-Visser class sister ships in the KNRM. She is the first vessel of her type in the KNRM to be built by the Damen shipyard and powered by MTU engines. Two 8 cylinder Series 2000 diesels, each producing 895 kW of power, propel the 19-m vessel via twin waterjets at speeds up to 33 knots (61 km per hour). The engines are housed in two separate, watertight engine rooms. But the really clever trick is that they carry on running even if the boat capsizes and completes a full turn around its longitudinal axis. On the Nh 1816, all the computer systems are watertight too.

Crane capsize
On one occasion the crew, as part of a training exercise capsized the vessel using a crane. The engines did not keep running on that occasion because the ship turned over too slowly. They are switched off to protect them if the overturn maneuver takes longer than 30 seconds. But then they can be restarted straight afterward without any trouble. If it was really stormy out at sea and the waves were a lot higher than the lifeboat, the Nh 1816 would overturn and right itself in just a few seconds. So then the engines keep running the whole time.

To make short duration upside-down running possible, MTU designers specially configured the crankcase venting system and the engine oil galleries so that the oil cannot run into the intake system if the engine completes a 360° rotation. MTU has previous experience of producing engines with overturn capacity for Britain’s voluntary lifesaving service, the RNLI. The company is also able to demonstrate it on the test stand at MTU Benelux.

By Jake Frith