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September 26, 2008

Of shoes and ships and .....

My posting of a painting yesterday made me wonder where I'd hidden other pictures of ships and sure enough I find I have them tucked into the computer all over the place. The one shown here is of the tug in the painting and shows off her size and her pedigree lines quite nicely. She and her sister, Wolraad Woltemade, are long and rather lean with very clean 'entry' lines at the bow. They have a very high turn of speed - important when you operate on "Lloyds Open Form" which stipulates a "No cure; No pay" operation. The first tug to the casualty that can get the Captain to sign the form and accept the tug's assistance, gets the contract. There are no prizes for getting there second.

John Ross.JPG
The Salvage Tug "John Ross" entering Grand Harbour, Valetta in Malta some years ago. The picture was sent to me by a friend who happened to catch her entering the port.

Once you have a line on the casualty, you have to get the victim to safety - or you don't get paid. So now you not only need the speed to get there, but now you have to have the gear and the power to drag it out of danger and into safety. Often in the most appalling weather and in heavy seas. So you need a tug that is seaworthy, powerful and fast when she needs to be.

This pair have twin engines, but a single screw. The propeller is a variable pitch mounted inside a "Kort Nozzle" which increases the power by creating a "jet" effect. Twin rudders make her very manoeuvrable, allowing a turning circle that makes the ship heel steeply if used at high speed. The twin engines can be used singly or in tandem with both driving into the single gearbox. In addition there are a range of generators which provide electric power for winches, lights, flood lights and the huge derrick mounted on the mainmast. The "Bollard" Pull - the measure of a tugs power is reckoned as 150 tons pull, which is very high by any standards but enormous when measured against the usual 20 - 30 tons for a large harbour tug.

Her bow thrusters - which allow the Captain to swing the bow from side to side with the ship almost stationary in the water develop 800 shp which is the equivalent of most small tugs in the average ports total main engine output. These salvage tugs are in another league altogether, as are the men that operate them.

Posted by The Gray Monk at September 26, 2008 02:56 PM

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