M/S Finnarrow Ballast System Conversion

The roro-vessel FINNARROW was acquired by Finnlines at the end of 1997.

In order to adapt the vessel for quick loading and unloading required by the truck service, FINNARROW was converted to provide through-driving facilities from two decks, i.e. the main and upper deck, by retrofitting a bow ramp to the vessel.

A new ballast system was needed as the existing system had insufficient ballast capacity for quick loading.

The new system was designed by Deltamarin Ltd. The system consists of a ballast system for the bow and a system for the stern. The two ballast tanks in the bow have a total capacity of approximately 500 cubic meters, and the two stern ballast tanks a total capacity of approximately 1,000 cubic meters.

The system is fully computer controlled. The desired bow and stern draught is given as input to the computer which then controls the starting and opening of valves. When the desired draught has been achieved the pumps stop and the valves are closed automatically.

With the new system, the required ballast can be pumped in approximately 20 minutes.

All ballast system equipment was delivered by ACOMARIN Ltd Oy.

The system consists of the following components:

Nor-Control ballast system computer (modified existing system)
2 ballast pumps, 1200 cubic meters/h/pump
2 sea chest valves, DN500 butterfly, double flange
2 adjustable DN450 butterfly valves
12 DN450 butterfly valves, open/closed control
electro-hydraulic EHS actuators
complete instrumentation for pressure, level, measurements etc.

The electro-hydraulic actuators eliminate the need for external pipelines. Each actuator has its own small built-on power unit that houses all the hydraulic components such as bi-directional pump, a tank, safety and lock valves, and electric components such as position transmitters, limit switches, pressure switches, relays etc.

The system does not require a centralized power unit, nor magnetic valve cabinets or expensive hydraulic lines susceptible to leaks.

The FINNARROW was docked at the Helsinki Repair Yard on 27 May, and left the yard on 3 July immediately entering service.