Slow Speed Steaming

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TxMarEng
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Slow Speed Steaming

Post by TxMarEng »

Just read in Trade Winds where Maersk may be considering slowing down to as litle as 11 knots on some of their new jumbos. Really a shame when you see the strides made to reach the power output required for those ships. This will be a real test for the B&W ME and Wartsila FLEX engines to see if they have the ability to manage operations at such low loads. Looks like the result may be long stretches of "sea trains" in a convoy fashion on the heavy traffic routes. Would expect other operators to follow suit.

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JK
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Post by JK »

Companies will actually have to stock parts and spares!! JIT deliveries will not be so JIT.

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ArkSeaJumper
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Post by ArkSeaJumper »

I would find it hard to believe that 11 knots is the most economical speed for these vessels.
I would normally find the best speed is only a few knots lower that the normal.

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TxMarEng
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Slow Steaming

Post by TxMarEng »

Maersk is a top notch outfit engineering wise, they turned a few of the old US flag SeaLand (ECON) vessels around that were Korean built and a disaster from the day of delivery. When you are burning in excess of 250 tons a day with today's prices it has to be quite serious to consider such actions. Still think nuclear is the ticket especially for the very large container ships. The design is there - just half of the latest US carrier plant. If a bunch of sailors (enlisted men) can operate them with a few months of training then surely a competent marine engineer can do it. However, they better move fast as there are only a handful of the former licensed marine engineers from the Savannah days left to give some insight and perhaps help layout a training plan.

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JK
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Post by JK »

Kripes-250 ton/day???
Our major icebreakers might burn 100 ton breaking ice.

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alanocean
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Post by alanocean »

That is a lot of fuel...The last tanker I was on with a full load through the ice was around 42/Tons per day. it was around 40000 GNT but still. I would hate to pay any fueling costs although the profit I am sure makes it worth while!

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TxMarEng
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Slow Steamimg

Post by TxMarEng »

Have to keep size in perspective as well as speed. These ships are doing 25 knots using over 100K horsepower. To make the same speed on some of the designs on the board under study would take almost twice the horsepower. Just heard yesterday that there is a concept design coming down the pike for a 9000+ teu nuclear for trans pacific ops. Of course they will now approach US gov't for actual design and there is only one yard in US that could build and that is Newport News. We all know the last disaster when they tried to build a commercial vessel. A good friend of mine that was one of the chief's on the Savannah feels that for the big high speed container vessels this may be the only way to keep them profitable. Savannah steamed over 350k miles on just 160 pounds of nuclear fuel. Actually have four friends that sailed on Savannah. Don't agree with MARAD spednding all that money on it for a museum though, would rather see a new schoolship for one of the academies - Texas perhaps. They got stuck with the ex MSC vessel Sirius. MSC could sail it but now the USCG says it can't be used as a schoolship. Seems they (USCG) have both in oars in the water however, they are feathered.

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Madzng
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Slow Steaming

Post by Madzng »

It is not just Maersk who have reduced speed, the majority of containerships are in the process of being slowed, even derated. In a lot of cases an additional ship is placed on the schedule, to maintain a service.

Freight rates are down, fuel costs are increasing and until the global economy begins to improve things will stay the same.

Dangerous goods and reefer containers have reasonable margins, but a standard dry cargo container does not bring in very much profit.

This is the reason for the modern ultra large containerships, more containers for a relatively small increase in fuel consumption.

One yard has just announced plans for a 22 000 TEU ship.
http://www.sustainableshipping.com/news ... e237&asi=1

100% speed 330MT per day, 50 % speed 70MT per day.

At consumptions like this even a small increase bunker cost per tonne will reduce the profitability of a service.

ArkSeaJumper is right, the engine is designed to be most efficient at around 75 - 85% MCR. Whilst the SFOC is higher at these lower loads the total fuel consumed for the voyage will be less.

Even when burning 700 cSt fuel the costs are high.

To date the RT-Flex has coped very well with the low load running, the software decides upon the number of fuel injectors to use, allowing good combustion to be maintained over the whole power range.

Nuclear would be interesting, but a lot of the "engineers" I have seen in recent times shouldn't be trusted with a kettle!

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ArkSeaJumper
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Post by ArkSeaJumper »

There is a big meeting in Athens on the 18 and 19 of Sep. on bunkering etc.
For a meger £1720 you will have all the answers to the problem of high cost of fuel.

Or more likely two days worth of unanswered questions.

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D Winsor
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Post by D Winsor »

There are going to be other factors to be considered when reducing the speed to save fuel on slow speed engines.
Many of these engines are connected to fixed pitch propellers so reducing speed means reducing engine rpm.
When engine RPM is reduced engine load is reduced turbo charger rpm is reduced thus reducing the amount of air for proper combustion of heavy fuel. Exhaust temperatures are reduced making exhaust gas economizers and aux. equipment ie generators operated off the steam generated will become less efficient if operated at all.
Combustion deposits will increase resulting in excessive wear and tear over the long term.
When the requirements to reduce emissions under new emission standards are considered. This will mean that operators will be forced to change to higher grades of intermediate fuels or diesel. We all know what has happened to the price of Diesel over past 12 months! There is already a push to have ship operators switch main engines to diesel in confined waters and passing major urban areas.
The winners in this market are the operators that have vessels with multiple medium speed engines and cp propellers giving much more versatility in how the vessel can be operated.

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ArkSeaJumper
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Post by ArkSeaJumper »

Slow steaming on a fixed pitch engine can be helped by a few things if you have decided it is a long term change.

The injector nozzles can be changed.

The turbo charger(s) also.

Most engines are designed with an upper and lower power.

I have never heard of anyone doing it, the ultimate 'fix' would be change the propeller.

CPP vessels will still need some modifying, if running low load, long term. the engine may well be running at the right speed, but would still choke up, possibly even glaze the liners.

In the short term, the normal practice is to load up the engine once or twice a day to blow all the shite out.

Dangers include, scavenge fires, and economizer fires.
Extra maintaince, more fuel burnt in the boiler, purchasing fresh water (not enough heat for the rainmaker), and pissed off Engineers.

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The Dieselduck
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Slow steaming the economies of the world

Post by The Dieselduck »

Interesting topic indeed. I find that nuclear will undoubtedly be pressured, pardon the pun, to make a comeback. Lets face it, bunker cost doubling year over year ought to make even engineers worried, not just accountants. We ought to worry not just with the issues of less than optimum operation, but with the refiners squeezing the crude just a little more to get the good stuff out, leaving us the really bad residues and all those associated issues.

The nuclear ship technology is not new and somewhat proven. and hey, if they can teach US military enlisted people to operate it, how dangerous can it be, ehehehe texmareng ( just poking ya) ... I am all for it, although I don't think we will see anything here in North America for a long while, but I can certainly see the Russian or Finnish yards marrying their experience and spitting out some massive double acting, icebreaking nuclear powered tanker or bulker.

Ultimately I believe the laws of economics will kick in, and yes perhaps a ULCS (Ultra Large Container Ship) might be built. But I don't believe these "growth" figure for world economies, and shipping in general, are sustainable, and I feel (as a complete layman) that we are headed for a correction, probably a major one, and probably sooner than later with the price of energy the way it is going up.

With that in mind, we can see a future where a balance will be reach - a surplus of ships will be available allowing older tonnage to be finally retired and scrapped, freeing up manpower for new builds, and slowing demand for bunkers, and loosening skyrocketing freight rates and improving safety records. Overall, relieving pressure on several major issues facing shipping today, and relieving some inflation pressure on the average joe across the globe.

Yikes, I was just doing the math on the fuel cost of that 330 MT per day consumption, thats works out to be about 230,000 USD a day at the pump! You have to cart a whole lot of tangerines and stereos to recoup that cost.
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Post by Wyatt »

Hey now everyone correct me if I am wrong, but is there not a formulea for calculating speed of a displacement hull and fuel /power consumed. I seem to recall a figure of somewhere of 3 squared over the calculated maximun hull speed of a displacement hull. Just a rough figure of course, but if the theoretical hull speed speed is 18 knots, then to get 1 more knot would require a 3 square increase in power. Thus the power required to thrust the US Nimitz to speeds in excess of 40 knots is somewhere in the niegbourhood of +200,000 horse power, and I know the Nimitz can do over 40 knots. But I digress, many years ago, the company I worked for commisioned the company WECL to perform speed /fuel consumption tests on our tugboats. After all these tests were completed, it took 2 years, it was found that by simply slowing down by a simple 2 knots the fuel savings were double. This is not new news. Displacement hulls require a definitive amount of horsepower to move at a certain speed. The logarithmic graph was very clear. Slowing down saved fuel, but to a point. The fuel savings on these vessels was quite substaintial for a very modicum amount of slowing down. I had many arguments with many skippers about this, and our ETA's according the WECL computers and the Skippers were quite different, and the WECL's ETA's were way more accurate. I found many of the old Skippers were adverse to slowing down. They measured speed by the position of those damn throttle levers, and not by the amount of fuel we were burning. I was very frustrated by thier lack of understanding. Anyway, this is a very interesting subject.
Cheers
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ArkSeaJumper
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Post by ArkSeaJumper »

The max speed of a hull is related to the length of the vessel, that is up to the point before it starts to plain.
Max speed of ship = 1.34√LWL (water line in feet)

Horsepower = displacement / ((150²/ hullspeed)²

The mathematicians out there can play with these old formulas.

Sorry about the imperial measurements, these formulas have been around for donkeys, but I haven’t converted them yet.

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Fuel Economy

Post by conrod »

OK lets forget the speed thing for a mo. Ulstein (Bergen Diesel) have been including Econometers on their engines / boats for .......25 years at least. I can recall on MK II UT 704's there being great big dials on the Bridge Fwd console, telling the driver when he was running at the most economical speed for the desired pitch setting.

More up to date, and the Ulstein UMAS system has real time graphics showing fuel consumption. This can be plotted on a graph and printed off in technicolour for the .............viewing.........of the........that chap upstairs.

I think many outfits are now looking at improving their Green Footprint, and as such want to run at the most economical speed. I for one have spent countless hours explaining this simple bit of kit to Bridge teams. Unfortunately when the charterer says its a hot shot run for drilling tools........he gets 100% pitch on both. Hey, they pay for the fuel, if they dont want to see reason regarding pullng back by a tad to reduce fuel, but maintain a good speed.........what can you do ? One thing I did manage to get across was more single engine running.........but that was more for load purposes. I would rather have 85% (or even 90) load on one engine, than 40% on 2.

What really gets my goat............is a 14 kt run from town, to some semi-sub, only 50 miles away, flat chat into a 5m swell, very noisy and uncomfortable, only to arrive at the 500 m Zone, and find the crane driver has gone for a 20 minute tea break. Well, that 20 minutes might have saved the bashing we get, and a cube or two of fuel, not to mention looking good for the Greenies.............and then the crane driver comes back...........and is busy with the drill floor, so you steam about for the next 12 hours, 1 engine on 15% pich. Hot shot...........my a*** !!

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