gCaptain.com

Big Motor Problems

By John G. Denham

I am impressed with the significant improvements that large diesel engine manufacturers are making in reducing offensive emissions, improving operational efficiency and cutting costs. When the “Firecracker Engineers” put their mind to it, it happens. Government is putting a lot of pressure on engine exhausts; the bigger the engine the more political pressure. Owners want more speed and efficiency and less cost. I have not observed any government involvement except to increase standards. The diesel engine manufacturing guys have addressed faster, more powerful, cleaner, efficient and less costly engines admirably, but there is another problem that effects operations: minimum speed.

The minimum speed limitation is an operational safety factor when maneuvering in confined, congested and special maneuvering areas. Rule 6 of the International and Inland Rules:

“Every vessel shall at all times proceed at a safe speed…” A gold mine for maritime lawyers.

The Pacific Maritime Magazine May 2008 issue’s feature article “Large Marine Diesel Engines” exemplified:

“APL recently ordered eight MAN B&W 14K98ME-C7 two stroke low-speed crosshead engines …will generate 115,000 bhp at 105 RPM …to be installed in eight new 10,000 teu container ships.”

As advertised the operating range of similar behemoths maybe as low 45 RPM and as high as 120 RPM. With direct drive and an efficient propeller the probable minimum speed may be 5.0 knots. Persons piloting such vessels may need to stop and start the engines any number of times due to circumstances; the engines are usually started with compressed air. Therefore knowing the quantity of consecutive start and stops is essential as an operating factor. There are two navigation considerations that must be resolved while en route: the safe speed of advance and the hydrodynamic effect of the vessel’s movement; the greater the speed the greater the effect. So far, ship handlers have developed procedures to reduce the speed of advance but as the engines become more powerful the solutions will be less effective.

While transiting a narrow channel there are three sub-factors involved that need to be considered to safely proceed: the bow wave, suction effect and the wake; all relate to speed and displacement. The details and an excellent explanation are provided in Caryle J. Plummer’s “SHIP HANDLING IN NARROW CHANNELS; Cornell Maritime Press.

Large direct drive diesel ships may have as many as 10 or 12 consecutive starts if the propeller is free rotating, but less if backing (need more air). Of greatest concern is an emergency full astern from full speed ahead; the air pressure may not be adequate to counter the propeller rotations.

Therefore, the ship owner must not only consider the environmental impact and economical advantage, but the cost of additional tugs and support services when entering congested and confined water. JGD.

John Denham is a retired USN Captain, Licensed unlimited Master and Pilot, maritime academy teacher,and author with extensive experience as a marine consultant. He writes for Pacific Maritime Magazine and is the author of The Assistant and DD 891.

Never Sea Land brings us the largest engine ever built:

The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine is the most powerful and most efficient prime-mover in the world today. The Aioi Works of Japan’s Diesel United, Ltd built the first engines and is where some of these pictures were taken.

It is available in 6 through 14 cylinder versions, all are inline engines. These engines were designed primarily for very large container ships. Ship owners like a single engine/single propeller design and the new generation of larger container ships needed a bigger engine to propel them.

The cylinder bore is just under 38″ and the stroke is just over 98″.

The largest piston in the world!

More Enormous Piston Rods.

“DU-Sulzer 12RT A96C” translated to “One large MFD”

How it works. [Continue Reading →]

Starting a Wärtsilä 6 L 64… for a truly amazing engine read our post: The Wartsila-Sulzer Super Engine

I have been amazed lately by the number of errors in both media reports and political commentary related to the the container ship Cosco Busan that allided with San Francisco’s Bay Bridge. We first reported on the confusion between the words allision and collision but that debate is mostly semantic. The errors have grown as the debate has reached a national audience.

The most troubling mistake is reports that infer or flatly state the vessel is a tanker. This mistake has been made numerous times as can be seen by doing a simple google news search for the incorrect term but most seriously in USA Today’s, America’s most widely distributed newspaper, headline (page A6 of November 12th’s edition): “Coast Guard: Tanker crew tested for substances.”

The media is not the only “informed” party making this mistake. The San Francisco Chronicle reports on a statement by San Francisc’s mayor:

Newsom saw the disaster as an even larger statement on the weakness of America’s dependence on oil.

“We can do better than large oil tankers coming in and out of the bay of San Francisco, and move to a more energy independent future,” he said at Crissy Field. “We’ll continue to have these kinds of disasters inevitably if we continue to have more tankers come in and out to feed our addiction.”

So for those in the media or with a passing interest here is a picture of an Oil Tanker and the Cosco Busan:

Tanker

Container Ship

The major difference between the two is: a tanker transports liquids and a container ship transports containers filled with solids (i.e. toys, home furnishings, industrial supplies…). So before the flood of emails arrive… if the ship that hit the San Francisco Bay Bridge was not transporting any liquids why did it have 58,000 gallons aboard? The answer is… for the same reason your car carries 24 gallons of gasoline.

The fuel spilled in the bay was all to be used by the ship’s enormous engines during the long transit back to China. Had this ship been an oil tanker the spill could have been as large as the one caused by the oil tanker Exxon Valdez… then again probably not since the oil in those ships are now required to be protected by a double hull.

Here is some video of engine room operations during a crash astern test for sea trials. Nothing too exciting but you can find more sea trial test of the Hansa Papenburg HERE.