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Berlin's oldest passenger ferry goes electric
Posted: Wed May 22, 2024 9:59 am
by dan_b
Re: Berlin's oldest passenger ferry goes electric
Posted: Wed May 22, 2024 1:38 pm
by AlBargey
Wish they showed some decent pictures of the install!
But how can a 100t steamer burn 150l diesel an hour in it's engines!? - I can imagine that will pay off fairly quickly even with Torqueedo's over priced offerings.
Crossing the channel with our 1950's 2 stroke Detroit diesel pushing our 120t or so barge we only managed 40l hour, for 15 hours, and I was shocked with that!
Re: Berlin's oldest passenger ferry goes electric
Posted: Wed May 22, 2024 4:11 pm
by John_S
I expect it has a lot to do with speed.
Both the ferry and your barge will be limited by their speed length ratio. Generally, for displacement, ie non-planing hulls,
max hull speed = approx 1.3 * (waterline length)^0.5
where hull speed is in knots and waterline length is in feet.
The constant, 1.3, can vary between about 1.2 and 1.4 depending on the prismatic coefficient of the hull.
It is likely that the ferry was over powered and the coxswains went at wide open throttle a lot of the time, thus burning diesel unnecessarily. Coxswains don't pay the fuel bill. By contrast, you, as an owner operator, would probably go at a bit under max hull speed and save considerably on fuel.
A rough rule of thumb is that 0.2l of diesel produces 1hp. Thus 150l of diesel is equivalent to twin 375hp engines, or approx twin 250kW engines. These figures are approx and rounded, in particular, I have not taken into account engine hp or shaft hp, after gearbox losses. The new engines are twin, 50kW engines which is about 20% of the estimated power of the old engines.
Also, I am not sure if the vessel was repowered from diesel engines or from steam engines with diesel burners which are much less efficient than diesel engines and thus 150l would be equivalent to a lower horsepower.
John