[GTO]

Mod Note: Thanks for sharing! Thread moved to the Commercial Vehicle section where we usually discuss all the Big BHP machines (ships, planes etc.).

[T1000]

Der MJ@Mariner,
Informative post.

Keen to know, how break downs are handled at mid sea?

How compressed air(450psi) is produced? is there a compressed air tank?

Look forward to details about ancillary machines which support the main engines.

Thank you,

[rav11stars]

Thanks a lot for the post. Writing is a subtle art and there are few in this forum who've mastered it. You'd just love to read them. Your post is one of them. It has just the right amount of info and nicely spaced paragraphs to encourage one to read rather than scroll through.

Thanks again and please write more about your experiences. I'm interested as to how the Captain can manoeuvre such huge vessels. How do they gain this experience? Do they have any technical aids like an auto-pilot on a flight to help them?

[adi.mariner]

Originally Posted by T1000

How compressed air(450psi) is produced? is there a compressed air tank?

Hello T1000. There are Air Compressors which compress the Air to 30 Bar (450 psi) required for starting the Engine. Mostly they are of the reciprocating type (Piston inside Cylinder). Other than those, there are Air Compressors which compress the air to around 7 bar (101.5 psi) which is required for Control Systems and other Auxiliary Systems on-board.
Regards.

[MJ@Mariner]

Originally Posted by T1000

Keen to know, how break downs are handled at mid sea?

Hi T1000,

As explained by fellow BHPian, there is tank or technically called air reservoir which holds 30 bar compressed air for immediate use.
Now let me explain a bit how the engine is started using compressed air.

First some Acronyms, TDC. Top Dead Center, ECU Engine Control Units

The Electronic engine is fitted with an angle encoder which detects exact location of the unit and the encoder is calibrated for the first unit, so other units positions are relative to number 1 unit. For a 6 cylinder 2 stroke engine the firing order is 135426.
Now once angle is known, the ECU knows which unit is at TDC. Now based on the firing order the compressed air is let to the unit which is at TDC. This compressed air pushes the piston down and engine starts to turn. The rotation of the engine makes the other pistons to come to TDC and compressed air is let on these pistons, which makes the engine to pick the RPM. Once engine reaches the RPM where it can develop enough momentum to burn the fuel, the fuel is pumped by the booster pumps. The fuel is injected at around 350bars.


Once the engine up running on fuel, the RPM is raised and speed of the vessel / ship picked up.

For breakdowns:
Normally we make sure the strict maintenance schedule is followed and generally the breakdown at sea are less.
But at an unfortunate event of breakdown, no choice but to solve the problem and make the engine run again.
The challenge is not doing the breakdown maintenance, the challenge is to carry out maintenance when the ship is rolling. As the ship loses the engine it won't be stable and does all sorts of dance as possible. Now to carry out the maintenance as per the rolling is very challenging.

Originally Posted by Sutripta

What would be the impeller diameter of these turbos?

The diameter of the impeller is around 1 metre to 1.5metres

Originally Posted by V.Narayan

What sort of clutch connects the engine to the propeller. I assume when this giant engine is being started with compressed air it is de-clutched from the propeller shaft and then as it starts to run on its own it is clutched in and the ship starts to move. How large & heavy is your propeller.

As explained by fellow BHPian it is direct coupled engine and no clutches are provided. The diameter of the propeller is 9meters and one turn of the propeller pushes the ship by 6meters.

Originally Posted by rav11stars

Thanks a lot for the post. Writing is a subtle art and there are few in this forum who've mastered it. You'd just love to read them. Your post is one of them. It has just the right amount of info and nicely spaced paragraphs to encourage one to read rather than scroll through.

Thank you for the encouraging comments.

To become a seagoing merchant vessel Captain it takes any where from 10 years to 15-years of experience. In these years one gains enough experience and understands behavior of the vessel, understands the effect of sea currents and winds and understands effects of tides. As in case with the vehicles (sedan, SUV, MPV. etx) different vessel behaves differently to the wind, current and speed.
Vessels like containers carriers zoom at 20 to 22 knots but Crude oil tankers and Bulk carriers (iron ore, grain, cement etc) hardly moves at 15knots. Main reason being the amount of cargo they carry and how much immersed they are in water.
A crude oil tanker (Very Large) has an immersion of 25meters under water (imagine a 6 storied building) and carry 300, 000Tons (3 Lakh Tons) of Crude oil at a given time.

Regarding the technical aids, there are whole lots of them which assist in safe navigation in any waters.
We have Electronic Charts ( Some thing like G-Maps), GPS (for position), Compass (for direction), Radars (for surrounding info), Auto Pilot mode etc etc.

[Jeroen]

Originally Posted by MJ@Mariner

The diameter of the impeller is around 1meter to 1.5meters

Running at 13.000 RPM is quite the engineering/design feat

Originally Posted by MJ@Mariner

As the ship loses the engine it won't be stable and does all sorts of dance as possible. Now to carry out the maintenance as per the rolling is very challenging.

Twice in my career we had to do some major repair in the middle of the Indian oceans which left us with no propulsion. Both times on a 12.500 B&W 6 cylinder engine. In both cases we had a cracked cylinder liner.

Which meant taking of the cylinder head, pulling out the piston, pulling out the cylinder liner, clean, fix and then get everything back in. On a pitching and rolling ship quite an exiting job! As pointed out, all very heavy components, but also very heavy tools (hydraulics ) required.

The low speed engines are very reliable. We had more problems on the medium speed engines with all sorts of stuff breaking. But on those ships we usually had 2 or 4 main engines. So shutting one down is not a big thing.

Jeroen

[T1000]

Originally Posted by MJ@Mariner

Hi T1000,
As explained by fellow BHPian, there is tank or technically called air reservoir which holds 30 bar compressed air for immediate use.
Now let me explain a bit how the engine is started using compressed air.

Thank you for the detailed response.

Is there a diesel engine or an electric motor that powers the air compressor.

What happens if the air reservoir gets empty.

Cruise Ship Rams Into Tourist Boat and Dock in Venice, Injuring at Least 4
Https://www.nytimes.com/2019/06/02/w...hip-crash.html

What could have gone wrong in this case?

[ringoism]

Thanks for this rather interesting diversion re: a very different sort of "motor vehicle" than we normally see here!

I worked briefly installing new generators in a very old (1952 to be exact) Italian ocean-liner that some years later was being used by an NGO as a mobile hospital ship. I was mightily impressed at the time by the engines, two of them: two-strokes of ten cylinders each, each unit something above 20ft tall and sixty feet long... the cylinders were of 30-inch diameter and 4-1/2 foot stroke, and IIRC they put out 15,000hp, I can't remember if that was each or together. These, too, were started with compressed air, but everything was 100% manually controlled. I was told at the time that modern ships had engines much smaller physically that had much more output.



It had been commissioned as the MS Victoria, later was converted and renamed the Anastasis... under which it served for nearly three decades...

before ending up, as so many others, at Alang in Gujarat! (Even when I was onboard in the mid-1990's, it was a complete rust bucket!).





A vastly more impressive ship to me was the SS United States, built around the same time in Virginia in a joint effort between the U.S. Navy and United States Lines, at a staggering cost of nearly $80million. Fast and luxurious, and sporting an astonishing 248,000 shaft horsepower (I would LOVE to see the engine room on this one!), to this day - in 2019, nearly seventy years after it was built - it still holds the Trans-Atlantic speed record set on its maiden journey, being capable of cruising at 35-knots, with a supposed top-speed (considered a State secret, never published / confirmed - but at one point leaked) of 43 knots (80kmph)! Really something for a near 1,000ft-long vessel!



Also had a highly compartmentalized hull, a largely aluminum superstructure to save weight, and "fireproof" construction, the only wood ever allowed inside allegedly being the butcher blocks and Steinway piano!

Check the Wikipedia article, or other articles like this one:

https://www.maritime-executive.com/e...-united-states

It has been in danger of being scrapped for years, but its would-be conservationists (headed up by the designer's grand-daughter) haven't yet given up hope:

http://www.ssusc.org

... It came to rest in Philadelphia during the time I lived there; There've been many plans before and since to restore / re-purpose it (retired in 1969, expensive to run and fast as it was, unable to compete with emerging airline travel). All have thus far come to nothing, but it is an amazing part of maritime history, and one can hope a feasible plan for its long-term utilization can finally come to fruition.

This one I always thought it would be thrilling to sneak aboard sometime and explore... though a YouTube video now shows it's true condition... very solid structurally, but thoroughly gutted and thus rather uninteresting inside! Still, with an imagination one might "see" many of the famous personalities who once traveled on it, sitting at whichever bar, enjoying a stage show, or sunning themselves on the decks, while being served hand-and-foot (there was one staff for every two passengers on board!).

I might add that modern-day cruise-liners are just incredibly ill-proportioned and ugly - floating bricks for the most part - in comparison to these sleek vessels of yesteryear.

-Eric

[ringoism]

P.S. (on account of time limit couldn't add this to the previous): An interesting history of the Victoria/Anastasis, originally designed to call on the port of Bombay, among other places:

https://ssmaritime.com/Mercy-Ships-V...-Anastasis.htm
https://www.midshipcentury.com/anastasis

[behaln]

Hi , interesting post on the main engines of the ships. I have been commanding LPG/LNG tankers and glad to see a post on the massive marine engines.

Let the questions flow, would be glad to answer the queries of the fellow bhpians.

Please find few pictures of my present baby.

[MJ@Mariner]

Originally Posted by behaln

Please find few pictures of my present baby.

Waw, Nice pics bro. How are these pics taken. From helicopter or a drone.

[behaln]

Originally Posted by MJ@Mariner

Waw, Nice pics bro. How are these pics taken. From helicopter or a drone.

Hi, these were the latest pics taken by the Panama Canal Authority during our last transit.
They have professional photographers using drones to capture the images. The images are then sent to the owners on chargebale basis.

[adi.mariner]

Originally Posted by T1000

Thank you for the detailed response.
Is there a diesel engine or an electric motor that powers the air compressor.

Hello T1000,
Generally, there is a slow speed 2 stroke engine which is directly coupled to the propeller for Propulsion duties. Apart from that, there are multiple smaller auxiliary engines (usually 4 stroke, medium speed) which are used for Electricity Generation on-board. They supply the electricity (usually 440 V, 3 Phase) to all the auxiliary equipment like Air Compressors, Cooling Water Pumps, Lubrication Oil Pumps, Air Conditioning Unit for the Accommodation (Living Space for the Crew), etc.
Coming to your question, generally there is an Electrical Motor which powers the Air Compressor. But there are also some ships which have a Diesel Engine powering the Air Compressor.

[Jeroen]

Originally Posted by adi.mariner

Hello T1000,
Coming to your question, generally there is an Electrical Motor which powers the Air Compressor. But there are also some ships which have a Diesel Engine powering the Air Compressor.

I once had to start up a completely dead freighter as part of a salvage job. Completely dead ship and it had been like that for several weeks. No electrical power, but also no pressure left in any of the pressure bottles/vessels.

The procedure was as follows:

There was a small pressure bottle with a hand pump. It would take about twenty minutes of hand pumping to get that up to sufficient air pressure. That would enable to start a small diesel set that would drive, through a mechanical clutch, a small compressor. With that we filled one of the main starting bottles which subsequently allowed us to start one of the auxiliary engines. With the first auxiliary engine back in service we could restore electricity to the main grid. Which allowed us to subsequently power up one of the electrical driven main compressor.

That gave sufficient air capacity to start another auxiliary engine, bring it on the grid and start up the rest of the systems. Quite interesting trying to figure out how to start up an, unknown to us, engine room!

Jeroen

[T1000]

Originally Posted by Jeroen

That gave sufficient air capacity to start another auxiliary engine, bring it on the grid and start up the rest of the systems. Quite interesting trying to figure out how to start up an, unknown to us, engine room!

Jeroen

Looks challenging, so small or big, every engine requires compressor air to start.

The job is really not for the faint-hearted