I remember one of the ships my father was on had pitchable propellers. you could reverse the pitch to reverse the ship.
I remember one of the ships my father was on had pitchable propellers. you could reverse the pitch to reverse the ship.
So, if they're driven off the crank, is there even any kind of in-and-out box so that you can idle in neutral?
The pitchable propellers make sense, assuming that they can be made reliable.
No in/out, no neutral. Stop the motor if you don't want the screw turning. Loose a propeller blade and Very Bad Things happen.
I'm trying to recall if I was ever on a ship with a variable pitch prop. I don't think so. I was on a real POS once, the MV Star of Texas. It had two V16 medium speed Diesels of around 10K HP each or so that broke down all the time. The propeller on that one went through a gear reduction box that joined the output of both engines and gave a standard prop speed of around 100 RPM, but I think to reverse, they still just ran them backwards. There was some way to disconnect the motor from the output gearbox so you could run one motor while the other was broke down, a frequent occurance. I don't think there was an actual clutch mechanism. I think you had to have the motors stopped to engage/disengage. I'm not sure about that SL7. That one had two screws and they could run one forward and one in reverse and spin it right around.
JetMech wrote:Dr. Hess wrote: Andy, Actually, a big Diesel engine is more fuel efficient than a boiler/turbine.I'll second that. The boiler-fed ship I was attached to guzzled fuel like you wouldn't believe.
As a former licensed stationary high pressure boiler engineer (I had a NJ high pressure blue seal boiler operator's license in a past career), I would suspect that ship had an out dated or poorly configured boiler. Not that boilers don't have thier fair share of problems too; long warm up periods and lots of tube cleaning needed if using heavy oils for fuel, ect.
HappyAndy wrote:JetMech wrote:As a former licensed stationary high pressure boiler engineer (I had a NJ high pressure blue seal boiler operator's license in a past career), I would suspect that ship had an out dated or poorly configured boiler.Dr. Hess wrote: Andy, Actually, a big Diesel engine is more fuel efficient than a boiler/turbine.I'll second that. The boiler-fed ship I was attached to guzzled fuel like you wouldn't believe.
She was 25 years old when I was attached to her (that sounds kinda bad!), and I don't know if/when the boilers were replaced, or much about how they were maintained.
All ships blow tubes at noon every day.
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