Anchor Control

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[Stuart2007]

That's impressive!

Presumably they only use that for short stops ie whilst waiting to enter harbour. They don't rely on it as the main system, do they?

I mean wouldn't that use a hell of a lot of fuel running the engines up every time there was a tide or current?

Stu

[Britannic]

Well, to be honest, I'm gonna get ss08 instead of VS cos, even though vs has sailing ships and subs and that, as you said, it somewhat lacks the realism that ship sim has. the autopilot is pretty useless really, I admit, but the little things like the speedo and touch-controls which allow you to controlo the ship staright of the dash. However, I am aware that this would up the resourse use, so, lets' just stop seeing if we can dig up things from vs. Virtual sailor is a damn good game, prehaps even as a simulator, but I have a feeling ss08 is gonna considerably better...

[AriesDW]

That's impressive!

Presumably they only use that for short stops ie whilst waiting to enter harbour. They don't rely on it as the main system, do they?

I mean wouldn't that use a hell of a lot of fuel running the engines up every time there was a tide or current?

Stu

To what are you referring?

[Stuart2007]

To what are you referring?

Hmmm... If you look above I was referring to QM2s 'virtual anchor'. I mean they surely don't keep the engines running to hold their position when mooring for any length of time.

Stuart

[Eemspoort]

No, they won't! But it's a very high-end system for waiting to enter port or a lock.
a huge inland-tanker called the "Vlissingen" is equipt (??) with this system as wel, to stay in one position IN locks, because the ship is to heavy to more on the usual mooring-facilitys in the (inland-)locks.
The "Vlissingen" is the biggest inland-bunkervessel in the world,for suplying oil to see-ships, and she can use that system for staying alongside the seeship as well.

[Stuart2007]

Thanks for that.

But would the QM2, on a cruise in the Carribean and it is moored at sea (such as the harbour being too small) for say 12 hours would it use this system still, or run a conventional anchor.

That must use a hell of a lot of diesel to keep the main engines going.

Stu

[Eemspoort]

Well, my geuss is, that they use conventional anchors for longer periods. I'm pretty sure of that.
Because it would cost to much diesel, indeed.

[AriesDW]

Thanks for that.

But would the QM2, on a cruise in the Carribean and it is moored at sea (such as the harbour being too small) for say 12 hours would it use this system still, or run a conventional anchor.

That must use a hell of a lot of diesel to keep the main engines going.

Stu

Actually they use the system quite frequently. They use it in period of where they are standing off before entering a port or such. However, they have at times used it in seas that have an extreme depth. It is preferred, if I recall, they use the physical anchors as now a last resort. These situations being when wind and swells proove too much in fuel consumption. However, it is a primary anchoring system for the vessel. In instances such as all day docking, I have heard that again, pending on weather situations, they primarly will use the physical anchors because the sea bed is shallow enough that the anchors make contact with the ground, which causes increased resistance to the ship, should it beging to shift or move about.

RE: Fuel Consumption: The system, for the moment, is still being considered for how useful it really is for vessels of this size. They have programmed the system to have tolerances, of course. And remember, regardless of whether the ship is anchored or not, her engines and systems are still running to carry the load of the vessels energy consumption and so on. So, I believe the mentality behind this system is that, the systems are running anyways and the engines and thrusters will not be running at high revs throughout the entire duration of the anchoring, they would only really function in low energy consuming bursts (unless the ship is testing the system in a storm - LOL!), which therefore will keep energy consumption to minimal levels. Think about it, if it fired the bow thrusters too hard to reposition itself in the proper parameters, then it would need to fire the opposing thrusters to slow the rotation or even correct it. So, I believe, again, it is very low fuel consuming and operates within certain limits. I imagine, similar to that of cruise control in a car, if certain parameters are met, a small klaxon or notices indicates the system is being overwhelmed by the environment.

[Stuart2007]

Thanks Dave.

I suppose on a large diesel electric cruise ship there will be at least one main engine running at all times.

Isn't technology getting great. Planes that can fly themselves, ships that can steer themselves... Shame we have to steer cars still!

Stuart

[AriesDW]

Thanks Dave.

I suppose on a large diesel electric cruise ship there will be at least one main engine running at all times.

Isn't technology getting great. Planes that can fly themselves, ships that can steer themselves... Shame we have to steer cars still!

Stuart

Actually what you say is true. Even when vessels are in dry dock, they always keep at least one engine at a time running at full load. (of course the rotate the load I think every 24 hours). But yeah, it is essentially now different for the ship. In most cases, from what I understood when I talked to the crew of the Carnival Pride, they keep two engines operational even when the ship is in dock, just in case.

And BTW - Two cars are starting to drive themselvs. The MB S Class with self stopping and accelerating and the new Lexus LX 470 can parallel park itself.

[Stuart2007]

OK, a techie Q for you. (sorry, bit OT for this thread).

I once went aboard a Royal Navy (not warship) auxilliary ship as a guest and they said the engines needed to run for 2 days, gradually slowing to cool the equipment down after a transatlantic run.

No after coming off a ship sailing for 30 hours, the engines are shut straight down- yet I can't imagine the RN ship getting much hotter than the ferry even after 4 more days.

The ship weights were similar as was the output. The RN ship was maybe 5-10 years older.

So, in this day and age how come they can shut the engines straight down like that.

Stuart

[Eemspoort]

I think i can answer that partly.
If you shut down the engines without cooling down, they would eventualy crack, because of the temp-differences between the outside and the inside of the engine. The bigger the engine, the bigger the differences, the longer the cooling-down period lasts.

My Deutz main-engine is 47 years old, and that has it's reasons.
It has allways been coold down in the right way. If i would shut it down right after mooring, the Deutz wouldn't last another year. And since i'm very proud of my old engine running so fine, i allways wait for the exhaust-temps getting under 150 degrees Celsius. Then it's safe to shut it down.
How big it is? It rises aprox 2,5 metres above the engine-room floor. Total height would be aprox 3 metres.

Smaller high-rev engines like Caterpillars don't really need to cool-down, allthough it would be better to do so, for a longer life-span.

So, the very big engines in seaships need a much longer time to cool down. This will never change, not by tech or what ever else.

[AriesDW]

If I understand, many cruise ships run through a similar cooling process on the engines. Of course, it does depends on the type of engine. A lot of new ships are using new jet turbine style engines, and the cooling on this is different than the typical multi-piston, reciprocating engines. However, engines are not immediately shut off, the RPMs are lowered gradually and then eventually the engine is cut. There is even an automated shut down process that will manage the shut down for you, although the Engineer and Staff Engineer get ability to over-ride the process.

[Stuart2007]

Thanks Eemspoort. What type of vessel do you have? I'd love to get myself a boat- maybe the Pride of Bilbao or something similar...

But these ferries which keep them running... so you are saying that they are doing it wrong? That would explain the increasing smoke from POBIs exhaust stack last time I was on her.

Even the Dover-Calais ferries shut the engines straight down on arrival. Is there anyway they might be fitted with different cooling systems that keeps the temp down low?

Dave, I've seen a derivative of the Rolls Royce Olympus in a Royal Navy ship- are they really fitting gas turbines to civilian ships? Used to only be in small, fast boats. Technology is changng too quickly for me...

Stuart

Stuart

[AriesDW]

Cruise liners often have them The vessels that currently have jet turbines are  . . .

Queen Mary 2
Freedom of the Seas
Liberty of the Seas
Radiance of the Seas
Brilliance of the Seas

Aside that I do not know any others. They primarly use these engines to generate most of the electricity for passenger systems, however, they are still equipped with large reciprocating diesel engines, as well. (I think the common configuration is two engines and one turbine).

Ironically, this is the same configuration as the Olympic class. However, instead of being diesel fueled, they were steam. Interesting, eh?

[AriesDW]

And all of these ships, pending on the engine production plant, have such a variety of cooling systems, I think some sustain much more rapid shut downs then others with better ability. So. I would not be surprised if large engines can become shut down faster.

Also, here is a good point - why do you think the emergency shut down is called emergency? Because they don't want engines suddenly stopping too soon too often, eh? HA HA! Just being a smarty, no offence, mate.

[Stuart2007]

Now that makes sense- having a mixture of engine types.

When all now electric transmission, you run into port slowly using a couple of small engines and then when tied up you can shut down quickly (except the generators) and the main big engines most likely are slowed down as you say, maybe miles from land.

Stu

[AriesDW]

Well, remember, when a shipped is moored up, more often than not at least one engine is still running. Take cruise ships for example. When they moor up either at their final destination or a port of call, you can monitor the funnel and the engine vents and hear that the engine, or at least the turbine, is still operating at strong capacity. And we are not talking SMALL turbines, but ones that are the size of a medium bus. Also, you can always observe the funnel and you will see the entire time the vessel is moored, some smoke is always slipping from the funnel.

[AriesDW]

Also, and the large cruise ships keep all the engines running until they are moored up. It is just since they are at reduced speeds, the engines are naturally cooling down since they are not producing the same output as if out to sea. So as you say, yes, the cooling process begins from sea to port, however, they are still in use.

[AriesDW]

For manoeuvring (stations), as for entering particular areas (some traffic separation schemes), you need on the contrary to have all manoeuvring capability ready, engines running, propeller shaft generators decoupled, rudder pumps, etc... and Dave is quite right with the cooling.
But main engines will be shut down, and the cooling will continue (with secundary pumps) depending on the timing set from the bridge. Generators will continue running, of course. Passenger liners need to stay in standby during a cruise, I suppose? Ready to leave if the natives became dangerous. And they need much more electricity than any cargo ship.
Steam turbines burn(ed) fuel n° 2 or later diesel oil from the twenties on, I think? With heavy fuel you need to keep boilers and fuel lines warm.
Regards,
Luc

Yes, you are quite right.

In the steamer days, they dare not let a boiler come offline unless it was a must. It took about 7 hours to pressurize and get the boiler to a point to where it would significantly contribute to the power supply system, hence why steamers always burned.

In the case of modern cruise liners, you are right again, the simple demand on the system sustains that the load to require usually the jet turbine (or one reciprocating engine on older cruisers) while exchanging one passenger group for another (Such as when QM2 docks in NY, dumps off all her passengers and takes on a fresh load before leaving the same evening). From what I understand, they do disengage the reciprocating engines AFTER they are docked, and as I mentioned due to their reduced output, they are already in the cooling process before docking is even completed, and then as Luc mentioned, auxiliary cooling systems often engage to aid in the shut down process.

While these cruise liners are at a port of call, however, they cycle the engines on and off (aside the turbine, of course) and about 45 minutes before departure all systems are brought completely online and all systems inspected safe for departure.

As for larger, container or cargo vessels, yes, shut down is a different story. Generators are kept online the entire time and no major turbines such as the ones as cruise liners are on board or needed. I still thought that the engine for the most part was kept online, just at extremely low revs, unless it was staying over night . . .

So thanks for the knowledge, Luc! You are full of incredible info!

[Stuart2007]

I know that on Pride of Bilbao the engines are switched off as soon as tied up (as a mechanical gearbox with variable pitch the electric generators are seperate rather than fully electric transmission).

Although at both ends of the route shes only doing 5 kts for about 2-3 (stat) miles so as Dave says, then engines are beginning to cool down.

Typical anyway. I had an invite to visit the engineering areas of POBI, but the officer concerned has left. Shame as I'd love to see below decks (I used to travel regularly and got to know many of the crew).

[AriesDW]

Big diesel engines (MAN B&W for instance) are stopped because they have a minimum speed up to 30% of their max RPM. With a fixed pitch, it could be enough for 4 to 5 kts!
Regards,
Luc

Interesting. So when the vessels are running below those speeds, what is used then?

[Stuart2007]

They stick oars over the side and row backwards

Stu

[AriesDW]

LOL!!!

[Eemspoort]

Stuart, see my avator, that's my ship. An inland-bulk carrier.
Okay, that picture is a bit small....




And my main-engine!


On-topic:

Well, i've learned something more about seaship-engines now! This is a good exsample of the big differences between inland-ships and sea-ships.