This article came across my desk and I thought some might have input. I rarely hear of any engines being overhauled in any condition but out at sea earning its keep, well in the cruise industry anyway.
Some organizations might have no need for their ship to move for 2 or 3 weeks while being rebuilt, but realistically that is probably only government that can afford that. Having said that, the ultimate aim of this movement is not a bad idea.
Martin
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Campaign to overhaul main engines at drydock, not at sea
Craig Eason, 24 September 2007 Lloyds List
SHIPOWNERS are urging engine manufacturers to help lengthen the maintenance cycle of main engines to match dry dockings due to the difficulties in overhauling main engines at sea.
Charter rates are high and the demands for vessels to keep to tight schedules are more gruelling than ever.
The difficulties in finding suitable opportunities to stop a main engine long enough to perform heavy maintenance are compounded with port regulations that ensure certain vessels are on 10 minute standby to leave a berth in an emergency.
This leaves crews with the options of stopping at sea to overhaul main engines, or while at anchorage. Both are unpredictable and have their own associated risks.
These obstacles lead to uncontrolled maintenance of main engines by crews who take the few opportunities when they arise.
Therefore some owners want to see heavy maintenance times of main engines coinciding with five yearly dry dockings.
Oyvind Toft, technical manager at BW Gas, said overhauls during drydock periods would in many cases provide a good opportunity to carry out well planned and executed overhauls
“Spare parts and external support can be prepared beforehand,” he said.
”This would not only enhance reliability, but would also reduce unnecessary stoppages during normal sailing conditions of a vessel.
“We would need to have engines accumulating over 30,000 hours between services.”
To achieve such long operating hours between overhauls, he believes the manufacturers have to work on engine reliability.
“As shipowners we can improve our own practices, but we feel that the engine makers can put more into improving the design and the materials,” he added.
To back his research, Mr Toft, along with engineers at AP Moller, accumulated 300 reports on overhauls of modern large scale engines between 600 and 840 mm bore, where the bulk of the overhauls took place after between 10,000 and 12,000 operating hours.
He said results showed that in two- thirds of the cases there was some sign of a malfunction which caused the overhaul.
“But we noted that in about a third of the cases no anomalies occurred, cylinder cover, piston, liner and rings were all in good condition,” he added.
“If these overhauls could be carried out on the basis of condition the time between overhauls could be increased.”
Engine overhaul periods
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The Dieselduck
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JK
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Are companies willing to switch to MOD FO to get the length of time between overhauls though?
I try to discourage engine work on dock. Weird things occur, I've seen an engine room filled with sand after a yard worker blasted into an open seachest that also had all the valves off in the engineroom. Too bad we also had an engine apart. The first indication of problems was the fire alarm going off from the duststorm.
I try to discourage engine work on dock. Weird things occur, I've seen an engine room filled with sand after a yard worker blasted into an open seachest that also had all the valves off in the engineroom. Too bad we also had an engine apart. The first indication of problems was the fire alarm going off from the duststorm.
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ArkSeaJumper
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Are we taking the work and therefore the expertise away from the ships engineers?
Most of the ships I have worked on have staggered the big maintaince jobs, but done them in port. (not the tankers of course)
This meant that the crew was very familiar with the work, and if a problem accured, we were quickly and competently able to deal with it.
It is very difficult to overhaul multiple units on big engines at the same time in the space provided.
And of course don’t forget all the other work, boiler surveys, pump overhauls. etc.
Most of the ships I have worked on have staggered the big maintaince jobs, but done them in port. (not the tankers of course)
This meant that the crew was very familiar with the work, and if a problem accured, we were quickly and competently able to deal with it.
It is very difficult to overhaul multiple units on big engines at the same time in the space provided.
And of course don’t forget all the other work, boiler surveys, pump overhauls. etc.
Engine overhaul periods
Like we don't have enough to do after 5 years at sea, now they want us to carry out what I'd call routine maintenance in the scant period that qualifies as a drydock these days. If your fleet manager is like mine, the red pen goes through anything that can be carried out by ships' staff. It`s enough work just to keep up with the surveyor, looking for drydock workers `nests`, and trying to keep a handle on where all the `special tools' have gone to. Is it the cynic in me or would a scheme like that allow the owners to further cut the experienced staff they would have to carry aboard, as we would only be operators?
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Madzng
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Dock time is expensive, and in short supply, globally.
A typical Panamax containership could be in dock for 6 days, less if achievable, and alongside a wet berth for a couple more - before returning straight to service. The last docking I did the vessel went straight off the blocks and into service, only stopping long enough to ballast fully, once out of the yard.
Only work that currently can not be done easily whilst afloat is carried out in the dock. Propellor, stern tube seals, rudder, thrusters, stabilisers, ships side paint and any steel repairs.
Even this is changing diving companies are getting better and more sophistcated and the amount of work previously only possible in dock, is reducing. A report a couple of years ago, showed pictures and described the painting of a VLCC whilst afloat. By triming and heeling the vessel there was only a patch a few meters square that could not be coated.
Both ABS and Lloyds Register have in place schemes which allow the docking interval to be increased to 7.5 years, with a second in water survey taking the place of the orginal docking. Valves still need to be surveyed and the use of shipside blanks makes this possible.
Ships staff currently do all engine overhauls, both main and auxiliary. The main engine unit overhauls are staggered to ensure the engine is in good working order, that the work is managable and in order to spread the associated costs over several budget years. Imagine having to buy twelve new piston crowns, at once.
B&W two stroke slow speeds are already not far off acheiving 30 000 hours, if the engine is run well, even when burning HFO. The Wartsila RTA is closer to 12 - 16 000 hours, and the RT-Flex is supposed to be around 20 000 hours. ABB TPL turbochargers have a service interval of 30 000 hours. Mitsubishi MET turbochargers can go 100 000 hours before a bearing (plain white metal) change, requiring only a clean occasionally.
There is talk at the IMO of all ships being required to run on low sulphur MDO, to reduce the amount of pollution seen to be produced by shipping. This would obviously increase the overhaul time of most of the components effected by the use of HFO.
The quality of training for new sea staff in the UK, essentially already means that they are only operators and require considerable on the job training to acheive the knowledge to carry out the work required.
Shipping companies want their cake and eat it. The idea of minimum manning was that the ships staff and as much work as possible saved for the docking - how may times has anyone seen that happen??
Thier request in this instance will probably just mean longer TBO's with ships staff still trying to squeeze the overhauls in whenever there is a few hours spare.
A typical Panamax containership could be in dock for 6 days, less if achievable, and alongside a wet berth for a couple more - before returning straight to service. The last docking I did the vessel went straight off the blocks and into service, only stopping long enough to ballast fully, once out of the yard.
Only work that currently can not be done easily whilst afloat is carried out in the dock. Propellor, stern tube seals, rudder, thrusters, stabilisers, ships side paint and any steel repairs.
Even this is changing diving companies are getting better and more sophistcated and the amount of work previously only possible in dock, is reducing. A report a couple of years ago, showed pictures and described the painting of a VLCC whilst afloat. By triming and heeling the vessel there was only a patch a few meters square that could not be coated.
Both ABS and Lloyds Register have in place schemes which allow the docking interval to be increased to 7.5 years, with a second in water survey taking the place of the orginal docking. Valves still need to be surveyed and the use of shipside blanks makes this possible.
Ships staff currently do all engine overhauls, both main and auxiliary. The main engine unit overhauls are staggered to ensure the engine is in good working order, that the work is managable and in order to spread the associated costs over several budget years. Imagine having to buy twelve new piston crowns, at once.
B&W two stroke slow speeds are already not far off acheiving 30 000 hours, if the engine is run well, even when burning HFO. The Wartsila RTA is closer to 12 - 16 000 hours, and the RT-Flex is supposed to be around 20 000 hours. ABB TPL turbochargers have a service interval of 30 000 hours. Mitsubishi MET turbochargers can go 100 000 hours before a bearing (plain white metal) change, requiring only a clean occasionally.
There is talk at the IMO of all ships being required to run on low sulphur MDO, to reduce the amount of pollution seen to be produced by shipping. This would obviously increase the overhaul time of most of the components effected by the use of HFO.
The quality of training for new sea staff in the UK, essentially already means that they are only operators and require considerable on the job training to acheive the knowledge to carry out the work required.
Shipping companies want their cake and eat it. The idea of minimum manning was that the ships staff and as much work as possible saved for the docking - how may times has anyone seen that happen??
Thier request in this instance will probably just mean longer TBO's with ships staff still trying to squeeze the overhauls in whenever there is a few hours spare.