[BITList] Fwd: Lloyd's List: Send to Colleague - Another one for the Ginger Beers

[Michael Feltham]

I've never heard of this system

Mike
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Begin forwarded message:

From: enquiries at lloydslist.com
Date: 30 December 2008 08:03:28 GMT
To: mj.feltham at madasafish.com
Subject: Lloyd's List: Send to Colleague


The below article was sent to you from Mike Feltham (mj.feltham at madasafish.com 
) with the following message: I thought you might be interested in the  
article below.

How to make a quick getaway
Craig Eason - Tuesday 30 December 2008

MARINVEST, the owner of four panamax tankers with a unique emergency  
propulsion system using chain drives, has gained intellectual property  
rights for its invention for the Chinese market.

The Swedish shipowner designed the system for four vessels built with  
single slow-speed, two-stroke engines in Croatia.

The 55,000 dwt panamax tankers are designed, like most, with slow- 
speed engines and without gear boxes that can be used to de-couple the  
propeller shaft from the engine to allow another power source to  
provide propulsion power in an emergency.

The “take me home”, or power take-in, device is commonplace in vessels  
with high-speed engines and an alternative generator and gear box.  
Marinvest wanted to have a similar redundant system on its vessels,  
but without the gearing, which is not necessary on slower speed engines.

“We wanted a redundancy system for the main engine, firstly to provide  
a safety back-up, but secondly to allow the opportunity for  
maintenance,” said Marinvest vice-president Patrik Mossberg.

“We saw that it was difficult to find time to do maintenance on the  
main engine, when vessels would have to stop at sea, go off-hire, do  
maintenance, and then goon-hire again,” he said.

Maintenance while at sea, but not under way, is common because of port  
regulations.

With accepted safety rules, tankers and other vessels carrying  
dangerous cargoes have to keep engines on stand-by in order to be able  
to leave the berth within 15 minutes in case of emergency. This means  
that main engines cannot be overhauled or maintained while the vessel  
is alongside an oil terminal.

Marinvest wanted to overcome this.

“A gear solution [on slow-speed engines] would be so heavy and so big,  
it is not technically viable, so gearing was not the way forward,” Mr  
Mossberg said.

Therefore, it designed a system to allow the main engine to be de- 
coupled from the shaft. The vessel’s four auxiliary engines, which are  
normally used to drive the hydraulics for the cargo pumps, can then be  
used to provide emergency power to the shaft.

The shaft disconnection device is a cylindrical unit, approximately  
twice the diameter of the shaft, and a length about three times the  
shaft diameter. The key aspects of the unit are the two shaft  
connections with flange bolts and a set of radial dowels that allow  
the two flanges in the unit to be parted and to rotate independently  
of each other.

The emergency propulsive power, which may be hydraulic or electrical,  
comes from other suitable systems on board, which in the case of  
Marinvest is from the hydraulic cargo pump system.

In the Marinvest panamax vessels the available hydraulic power is 2600  
kW, at 270 bar. To the aft of the disconnection unit the system has a  
drum with sprocket wheels, and a quadruple chain drive transfers the  
hydraulic power to the intermediate shaft.

“The power goes through a chain drive, like a bicycle chain. We can  
disconnect in 15 minutes and can have a speed of up to 10 knots in  
moderate weather conditions,” Mr Mossberg said.

This allows the Marinvest tankers with the system to be able to meet  
their emergency departure requirements. The company said it has  
achieved approval from Det Norske Veritas, and is now looking at  
marketing the solution to other owners who want to get maintenance  
time while alongside in port, while still fulfilling the emergency  
power requirements to leave the terminal in a hurry.

“Firstly, we wanted this on our vessels, designing it ourselves as  
there was nothing available,” said Mr Mossberg. “Now we have had  
interest from engine makers and from the shipping community.”

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