Technical description
The FerryBox on board of a ship of opportunity consists of a water loop that gets its water from the outside, a data management system for control, data acquisition and storage and a telemetry unit for transmitting the data to shore.
Water Loop
FerryBox Hydraulic Scheme
The figure shows a schematic drawing of the German FerryBox system.
Water is pumped into the ship from an inlet in front of the ships cooling system. A debubbling unit removes air bubbles, which may enter the system during heavy seas. At the same time coarse sand particles which may be introduced in shallow harbours and which settle and tend to block the tubes are removed as well. Coupled to the debubbler is an internal water loop in which the seawater is circulated with a constant velocity of about 1 m/s. This already decreases the tendency for building bacterial slimes on sensors and tube surfaces. A small part of the water is filtered by a hollow-fibre cross-flow filter module for automatic nutrient analysis (this type of filter keeps the walls of the small hollow-fibres free of suspended sediments or bacterial films by applying high flow velocities, therefore avoiding bacterial contamination that could change the measured nutrient concentrations by microbial processes, e.g., nitrification, re-mineralisation.
For a reliable unmanned operation the system is supervised by an industrial programmable logic control which can shut-off the system in case of very severe errors and operates automatic cleaning cycles, e.g., in harbour.
Biofouling is prevented by cleaning of the sensors with tap water and rinsing with acidified water. Sometimes clogging of the water inlet in the ship interface causes problems by debris or fish. Since all flow rates are supervised by the system in such cases an automatic pressure back-flushing cycle is initiated which clears the inlet.
Measuring Parameters
Currently the FerryBox has sensors/analysers for the following parameters:
- water temperature,
- salinity,
- turbidity,
- oxygen,
- pH,
- chlorophyll-a fluorescence,
- nutrients (ammonium, nitrate/nitrite, phosphate, silicate),
- main algal groups (specific fluorescence)
- pCO2
- precise pH (0.001 pH)
- alkalinity
FerryBox Data System on board and on shore
FerryBox Data Management
The figure left shows a scheme of the FerryBox data system.
Data acquisition, data storage and data transfer to shore is controlled by an industrial standard PC. It is programmed in the programming language "LabView" (National Instruments).
Data are recorded from different sensors. Most sensors or analysers have a digital interface (RS 232). However, some sensors still have an analog output (see figure to the left).
Data can be transferred to shore and the system can be remotely operated by cellular phone GSM (internet access by GPRS or UMTS).
In Helmholtz-Zentrum Geesthacht all data are stored in an ORACLE data base that can be accessed from the internet.
User Control on Board of the ship
Screen dump of the display on board
One of the advantages of using "LabView" is the user-friendly interface for control of all systems on board the ship.
The left figure shows a screen dump of the computer display on board.
Since this screen is transferred to the land station in a one-to-one manner, the user on shore sees the same display as on board and can as well control all systems just by "clicking on the right button".
