Will a lot of different ways to propel a ship through the ocean what is considered to be the best?
From my limited knowledge on the topic it seems like small ships are fitted with Diesel engines and larger ships are gas turbines with lots of variations in between. With new ships going for all electric drive is it still better to have diesels and small gas turbines doing the low speed work and higher power turbines providing the dash speed. How high a priority does fuel economy possess in the fitting of engines. Are diesels best to provide a base load and gas turbines for increases speed best? Also is space taken up given a high priority in the list of what’s important. What should be done with the type 45 propulsion problems? A full rip out and replace job or just a fix what’s wrong. With energy weapons needing so much power it may be best to leave a big empty space on future ships for further fitting of what’s needed.
By: aditya - 22nd June 2016 at 20:09
Thank you for this very useful thread.
How does CODOG compare with CODAD and CODAG?
By: Jonesy - 21st June 2016 at 16:00
The more I look into it I get the feeling that no one has a perfect solution. Lots of ships all run with different mixes and combinations of power sources. The codes are enough to baffle most people. CODAG, COGLOG etc etc
There is no one ‘perfect’ solution. There is usually an ‘optimum’ solution for the given hull you want to propel. If you want to shunt 80,000 tons of VLCC along at 16knts effectively forever, economically, you want something low rpm with lots of power that runs efficiently so you end up accepting a big heavy low speed diesel. Could you power off turbines…yes with a consequent increase in fuel costs and a fair bit more empty space in the hull!. Could you do it off a steam plant….yes with less fuel costs than the turbines and a latency period building up pressure before you could put to sea….and the occaisional excitement of a boiler exploding.
Following the same theme if you want to outrun opposition torpedoes in a hostile littoral you’re not really going to be pleased if the designer pops up with space outlined for a low speed Wartsila diesel and a single shaft. If you want to do ASW and drag a passive array you might wish for an electric motor fitout that lets you shut off the noisy and high-vibration gas turbines….certainly the towed array operators will thank you for it.
If there is one or two layouts that are, perhaps, more optimal in more scenarios than any other you would probably point towards CODAD (COmbined Diesel And Diesel) for maximum cheap or CODAG (COmbined Diesel And Gas turbine) if you want cheapish and quickish!. Perhaps not so much ‘horses for courses’ rather ‘horsepower for courses’ maybe if you forgive the pun!.
By: F35b - 21st June 2016 at 12:53
The more I look into it I get the feeling that no one has a perfect solution. Lots of ships all run with different mixes and combinations of power sources. The codes are enough to baffle most people. CODAG, COGLOG etc etc
By: Yama - 21st June 2016 at 12:48
Diesels bulky but economical. Gas turbines compact and good acceleration but not very fuel-efficient. Steam turbines something in-between but very maintenance-intensive which is why they went out of style except in nuclear propulsion.
Electric transmission is bulky but reliable and makes handling the ship easier than mechanical gearing. As tonnage makes less up in ships’ cost these days, size constraints seem to have become less meaningful.
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June 21, 2016 at 12:16 pm