Finnjet is with it's 110.000 HP (around 81.000 kW) the best powered ferry of the world. (including all auxiliary diesels) She is able to reach 33 knots in just as low as 3 Minutes. And 1:30 is already enough to reach 21 Knots. Other vessels like Silja Festival or Serenade/Symphony need for this speed 5 minutes. Since 1977 the maximum speed has changed several times. Interesting enough to open a special page for Finnjet's speed!
In 1977 Finnjet's absolute maximum in speed was 31 knots. Anyway this speed was not needed for holding the normal timetable. So the maximum service speed so was 30,5 knots. As the turbines quite uneconomic in the Off season, Finnjet got 2 Dieselengines in 1981 which supply electricity for 2 electric motors located in the turbine hall. The whole Dieselconstruction is in deed quite heavy; Finnjet got ca. 500t more weight. Of corse this had consequences for the draft of the ship and so also for the speed. 31 knots couldn't be reached anymore easily. That was anyway no problem, as the need of the 31 knots was anyway just in the case of being late. In 1994 one of the last remaining problems was solved: 2 new gearings made it possible to use the engines much more customizable. Insted of the limit of 1 engine per axle now all engines could be used at once. Through the new gearings it's also possible to use combinations like 2 Diesels and one Turbine etc., which made fuel savings as high as 3000 tons per year. Furthermore Finnjet reached with all engines a bit more than 33 knots in the first testdrive, which means Finnjet could expand it's record as the worlds fastest conventional ferry! Anyway there are people saying Finnjet is only able to reach 33 knots when it's "empty", so unload. Also (this was already 1977) Finnjet needs almost 100m below the keel to be able to reach it's max. speed. (see diagram on the right) In 2001 Finnjet got a new bottom paint, that should have smoothed the shallow water effect, as same as modifications at Propellers and Turbines. This has again highered Finnjet's maximum speed to ca. 33,5 Knots and cut the fuel flow by 400 tons in just 2 months!
Finnjet's Maximum speeds in detail:
|Combinations||Maximum Speed||Maximum power (together; for both propellers)|
|1 Diesel||12 knots||7200 kW|
|2 Diesels||18,5 knots||14400 kW|
|1 Turbine||21,5 knots||27500 kW|
|1 Diesel 1 Turbine||23 knots||34700 kW|
|2 Diesel 1 Turbine||25 knots||41900 kW (37200kW*)|
|2 Turbines||31 knots||55000 kW|
|2 Turbines 1 Diesel||32,9 knots||62200 kW (57500kW*)|
|2 Turbines 2 Diesels||33,4 knots||69400 kW (60000 kW*)|
* Currently Finnjet has 2 Renck-Tacke gearings (Built 1994) with a maximum transferable power of 60000kW. With these gearings Finnjet is not able to use it's complete power (69400kW) at once. When both turbines are running at 100%, the electric motors can only take a small part of 2500 kW per gearing. Otherwise the gearing would be overstressed and soon destroyed... So, if Finnjet would get new gearings with a maximum transferable power of 70000 kW, Finnjet would have a higher Max. Speed. But as a changing out of the gearings is far from worthwhile (no savings would be expected) but just highering the maximum speed, it is not very realistic Finnjet will ever be able to use it's total power at once.
Sources: Text and table: FINNJETweb | Diagram: Infobrouchure "Finnjet - A new concept for fast ferryships" | Data is collected from several ferrymagazines and -books.
© Mathias Saken 2001-2004