|A Ralston Indicator circa 1950|
The calculations for maintaining our stability and trim were done by obtaining all the tankage figures for ballast and fuel tanks, then with pencil and paper the vessel Stability Book and Nories Nautical Tables working everything out. The whole exercise usually resulted in the vessel being "down-by-the-stern" so as to keep as much of the propeller in the water as possible. This was done to maximise the overall efficiency of the vessel as to fuel consumption and best speed which at 10 knots was somewhat of a joke but remember this was all in 1954.
Later on becoming an Officer and in a company that spent money on instrumentation we had a 'Ralston Indicator'. This was an ingenious instrument which frankly NAUTICAL LOG thoroughly enjoyed using. There is a picture above taken from my old Kemp & Young "Ship Stability" book. There was an engraved plate of the ship which could be lifted and balanced on gimbals and weights to place representing cargo, fuel, stores etc.,. A set of stability tables was inside the front lid and after doing all this placing of weights and reading of tables the stability condition of the vessel could be calculated.
And so we come to today over 55 years later where we still must calculate the stability condition of our vessel and it is even more important than ever to run her efficiently. With the use of computers we can calculate the whole thing in about the same time as it took to place one of those 'Ralston Indicator'weights in position with the tweezers provided. From FutureShip's ECO-Assistant comes easy to use software installed in any computer. The trim of a vessel influences her resistance and fuel consumption all of which depend on speed, displacement and water depth. Briefly by entering these into the ECO-Assistant application the calculation is made for the optimum dynamic trim for the specific operating condition.
|ECO-Assistant data screen|
An ECO-Assistant brochure may be downloaded from their website and they can be found at:
and at offices in Potsdam, Shanghai, China, Houston, TX
Please remember the 800 of our fellow seafarers held captive by pirates off Somalia, also ashore in wartorn and famine suffering Somalia.