Recent Posts

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1
Hello Mr. Tore,


I updated pages 426, 427, 428, and added the index back to Skizzenbuch. The latest version of Skizzenbuch is in the Dropbox folder...


Regards,
Don_
2
Hello Mr. Tore,


I was wondering (I know that could be dangerous) about conserving fuel... Running on 1 diesel engine and free tailing the opposite propeller looks to be the most economic way, but the rudder would be needed to maintain the course. Then again, they could be driving with 1 Diesel engine and using its e-motor as a generator to power the opposite e-motor to drive its propeller drive shaft; possible the rudder may be in use as well... Since the driving Diesel engine is getting resistance from its e-motor acting as a generator; does this mode cause more fuel use?


I believe both options are viable... Do you remember using one or both options, and which is the most economic?


Regards,
Don_
3
I guess pictures of the diesel engines of the different boats are rare and hard to find.
4
Further to my answer above I realize my image was not very clear so here is a photo of the real thing.
5
Hi!

It`s a good question of which I have no concise reply. On the VIIC 41 like  U-995 they did away with quite a lot of weigths as the greater diving depth caused a lot of weight increase hence they removed some equipment including the reversing mechanism, but ordinary VIICs in our fleet had non reversible engines as well as KNM Kaura ex U 995. So we can`t assume this is the reason when looking for the boats with reversible diesels. If somebody should feel for making a research a very visible sign that the engine is a direct reversible type is the reversing cylinder up front of the engine as can be seen on my image below may we could trace the boats based on engine photos.
Tore
6
Hi Tore, do you know when they gave up the direct reversible diesel engines? (which boats were the last ones?)
7
Hello Mr. Tore,


Thank you for the information on the startup sequence, and I was very amused about the shrimp factory story.  Things like that do happen in real life!


Regards,
Don_
8
Don
In addition to the above it was very convenient for the engineroom crew to have a tailclutch f.i. when having an engine repair and we wanted to have a testrun. With a propeller engaged you had to ask the officer on watch to double up the moorings prior to the test, with a tailclutch we were our "own masters" and could just disengage the propeller.
9
Don.
Most of the marine diesels in world are starting with a fixed blade propeller directly attached to the engine. Having a tailclutch is an exception rather than a rule. A direct reversible diesel as installed on the older VIICs had a manoeuvre sequence as follows: Starting with propeller engaged driving vessel ahead, manoeuvre astern, stopping the dieselengine, reversing the engine by axially shifting camshaft, starting the engine running astern, all manoeuvres carried out with the propeller engaged. This is standard manoeuvre for most of the marine diesels with fixed blade propellers, nothing special.
 Starting the diesel engine with the propeller engaged and submarine moored alongside might have a consequence, like one of my first battery charging alongside. We were alongside in a remote harbour way up north of Norway, we were moored at a wooden quay right in front of a shrimp peeling factory, built on wooden poles. I was on the bridge asking the engineer in charge if everything was ready for charging, got confirmation OK and ordered start the engine. Good old Kaura ex U995 made a jump ahead broke the moorings and ended up underneath the shrimpfactory while all the ladies working there ran screaming out of the shaken factory. The engineer in charge had forgotten the tailclutch.
10
Hello Mr. Tore,


If the main clutch is engaged and you are starting the Diesel engine, then you are adding the additional resistance of the prop/seawater which would be driving the U-Boat during startup. Is this not an extreme amount of load during startup? I don't doubt your answer, but I just want to verify the startup procedure...


Regards,
Don_
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