ENGINE ROOM BREAKDOWN
CROWLEY SEA FOX
PREPARED BY: DAVID TAYLOR MODEL BASIN
The Crowley Sea Fox is a combination container/RORO ship owned and operated by Crowley American Transport, Inc. The ship operates on a regular route, serving the U.S. east coast and the east coast of South America. There are two sister ships to the Sea Fox- the Sea Wolf and the Sea Lion. Each of these three ships is on the same trade route, with two weeks between each ship.
This class of ships was chosen to be studied by the Engine Room Arrangement Modeling group (ERAM) due to its characteristics being a combination container/RORO ship, and for the ships unique self-unloading container capability. According to the Captain of the Sea Fox, this self-unloading capability has been the one feature that has kept the ship competitive in the South American market. This capability is one of the requirements set forth by NAVSEA for the midterm Sealift ships being studied at present.
The ERAM group spent four days aboard the Sea Fox while underway, observing daily operations, interviewing the crew, photo documenting and video taping the engine compartment. The following report and accompanying photo log are the result of the Sea Fox ship visit.
CROWLEY AMERICAN TRANSPORT
@ Approximately or About
1 A/E First Assistant Engineer
AE Auxiliary Engine (Engine that drives the SSDG)
C/E Chief Engineer
DO Diesel Oil
ER Engine Room
FO Fuel Oil
FW Fresh Water
GE General Electric
HE Heat Exchanger
HFO Heavy Fuel Oil
LO Lube Oil
PAT Pollution Abatement Tank
PTO Power Take-Off (Shaft Generator)
RORO Roll On-Roll Off
SSDG Ship Service Diesel Generator
SW Salt Water
0.0.0 ENGINE ROOM, GENERAL
The Crowley Sea Fox is a container/RORO ship, built in Odense-Lindø shipyard in Denmark in 1984. All of the engineers in the ER are permanent employees of Crowley Maratime.
The ship is powered by a slow-speed Sulzer 7RTA68 main engine, with three B&W Holeby powered generators. There were no complaints about any of these engines, with the engineers stating the engines were excellent units. The C/E feels the ER is sectioned off into too many different compartments and rooms, each accessible through doors and openings in the ships structure. This sectioning is a result of the upper deck strengthening members required located in the ER. One possible advantage of this sectioning would be in the case of a fire while the ER was unattended, the sectioning serving to contain and isolate the fire.
The C/E said the lighting in the ER was presently not enough, and would like a lot more lighting. When the ship was new, there was adequate lighting; but as covers became dirty and the paint became discolored beyond cleaning, the ER became less illuminated. The 1A/E says the ships crew has added approximately 30% more lighting, and has reached the limit on the lighting circuit. If there were more power available on the lighting circuit, the ER crew indicated they certainly would add more lights.
The C/E would like more ventilation in the ER. If the supply fans were variable speed, the fans could more precisely control the supply of air to the ER. Variable speed fans would allow better control of the ER temperature by controlling the flow of atmospheric air being blown into the ER. Ideally, the C/E would like to have positive pressure in the ER at all times to ensure there is an excess of air.
On the same note, all of the ER personnel are in agreement that there is not adequate ventilation in the purifier room. When work has to be performed in this room, the crew has to turn on the supply fans for the RORO deck and open the escape trunk and the ER door leading to the RORO deck to increase the flow of air into the purifier room. Several years ago, the C/E indicated there was a problem with the electrical boards in the purifier room because of the high temperatures associated with the fuel oil heaters, etc. located in this room. This problem was controlled by directing supply air directly onto the electrical boards.
All engineers feel that applicable tanks should have sight glasses that go from as high as possible to as low as possible on the tanks. Those tanks that don't have, or are prohibited from having, sight glasses should have sounding tubes. There was a strong emphasis placed on the level gages as well. The engineers said the level gages on the Sea Fox were not very reliable, which makes the engineers very uneasy when transferring fuel oil and bunkering. In most cases in the ER, the level gages don't work at all.
A point was made that there should be plenty of ladders in the ER to get from one level to the next. ER personnel had to add at least one ladder to the ER to facilitate ease of movement between levels, and would like to add more in the future.
All the engineers feel there should be plenty of storage space in the ER. Places where spare parts are going to be stored should have access by an overhead crane to facilitate the ease of moving large parts. The engineers feel that no space should be wasted if it can be utilized as storage space.
0.1.0 CONTROL ROOM
All engineers agree the control room is spacious enough and laid out well. The only dislike in the control room is the General Electric main circuit boards. The C/E and the 1A/E say the circuit boards are confusing when compared with the wiring diagrams. On the same note, the wiring diagrams and the manuals for the boards are very confusing.
1.0.0 MAIN ENGINE
The Captain of the Sea Fox says the main engine would be ideal if it could provide a steady 3 knots at dead slow. Because of the propeller and the minimum rpm of the engine, the slowest he can achieve is 6 knots. The Captain said this speed was a little fast and made him uneasy when he had to maneuver in and out of port.
For routine maintenance on the main engine, Crowley has a contract with Sulzer to come aboard during each stop in Jacksonville, FL. The ships engineers perform preventative maintenance on the main engine. The C/E says the main engine has run great with very little problems. When Sulzer comes aboard to work, they provides a full complement of people to perform the maintenance when they come aboard.
The overhead crane above the main engine is a nice unit, with excellent fore and aft travel, but doesn't reach above the main engine turbocharger all that well. The C/E also said he would like to see more head room above the turbocharger, as well as the overhead crane
There is a spray-down system for the air side of the air charge cooler. This system is a fresh water system that serves to keep the cooler clean. The C/E says this system was a very good addition to the air charge cooler.
1.0.1 COPY OF ENGINE ROOM LOG
1.0.2 MAIN ENGINE PTO SYSTEM
On the stbd, aft side of the main engine is a PTO system that is supposed to serve as a shaft alternator. Since the ship has been in service with Crowley, the PTO system has not worked properly. The C/E indicated that the company has spent a lot of money and the ships engineers have spent a lot of time, and the PTO still does not work properly. The C/E said that Sulzer does not even advocate this type of shaft alternator any longer. Even if the PTO did work properly, it is in a bad location from a maintenance standpoint. One entire side of the PTO is butted up against the stbd side of the main engine. Consequently, one SSDG has to be run at all times.
1.1.0 MAIN ENGINE LUBE OIL SYSTEM
The lube oil system has a BOLL+KIRCH self-cleaning filter that will auto-shoot when the differential pressure reaches a certain level. A major shortcoming of the system is there is no bypass. Company policy mandates the engineers manually shoot the filter once each day, regardless of the differential pressure. But, if something were to happen to the filter, the lube oil system would be inoperable because there is no bypass. The C/E feels this is a bad design, and potentially hazardous.
1.2.0 MAIN ENGINE FUEL OIL SYSTEM
There is an in-line filtering system that runs in conjunction with the HFO purifiers. This filter is a fine filter that passes the HFO from the purifier as the purifier discharges to the day tank. The filter seems to function properly, and has a backflush line for cleaning, but the C/E feels that the purifiers should be able to do all the purification necessary for the HFO.
The C/E feels the HFO day tank is too small. The present tank only holds @ 24 tonnes of fuel, which is the equivalent of approximately 8 hours of fuel at sea speed. The 1A/E would like the day tank to have a 60-70 tonne capacity.
The HFO system has the same BOLL+KIRCH filtering system as the main engine lube oil system. See note above in section 1.1.0 MAIN ENGINE LUBE OIL SYSTEM.
The Sea Fox has 12 HFO tanks. The 1A/E would rather have less tanks, while retaining the same total capacity, as opposed to so many fuel tanks. The C/E commented that 8 tanks would be a good number, and would still be enough tanks for the ER crew to separate fuel purchased at different times.
Slops have to be stored in one of the HFO tanks because the slop tank is not large enough. In a 42 day round trip, the ER makes 50-70 tonnes of slops. These slops can be given away in South America, as opposed to being pumped off in the US or Europe for a large sum of money. The 1A/E believes there should be a larger slop tank to facilitate storage.
1.2.1 FUEL OIL CONSUMPTION
At sea speed, the main engine burns @ 65 tonnes/day of HFO.
1.3.0 MAIN ENGINE COOLING SYSTEM
1.3.1 JACKET WATER COOLING SYSTEM
This system discharges to the evaporator to serve as a heating medium to make fresh water.
1.3.2 PISTON COOLING SYSTEM
1.3.3 INJECTOR COOLING SYSTEM
2.0.0 AUXILIARY ENGINES
2.1.0 AUXILIARY ENGINE LUBE OIL SYSTEM
The 1A/E feels the auxiliary lube oil tank is too large. The tank is a 39 tonne tank, and the C/E also feels a 20-22 tonne tank would be more than sufficient.
2.2.0 AUXILIARY ENGINE FUEL OIL SYSTEM
The SSDG's burn blended fuel, which consists of approx. 90% HFO and 10% diesel oil. The C/E says there has not been any problems with the SSDG's and feel they are good, reliable engines. He also indicated he could burn straight HFO in the SSDG's if the fuel temperature was boosted up high enough. Presently the SSDG's are running the equivalent of @ IFO 190 fuel. Each of the three engines is rated at approx. 2000 horse power.
The fuel setting for the SSDG's is kept at 10.5 centistokes. This is accomplished by adjusting the fuel temperature for the amount of diesel oil that is to be burned. Since 10.5 centistokes is a constant viscosity, the higher the fuel temperature, the higher percentage of HFO in the blended fuel.
2.2.1 FUEL OIL CONSUMPTION
The SSDG's consume @ .75 tonnes/day of diesel oil and 5 tonnes/day of HFO.
2.3.0 AUXILIARY ENGINE COOLING SYSTEM
2.3.1 JACKET WATER COOLING SYSTEM
3.0.0 PURIFICATION SYSTEM
All of the purifiers are manufactured by ALFA-LAVAL, with the fuel oil purifiers incorporating the ALCAP system.
3.1.0 LUBE OIL PURIFIERS
There are two lube oil purifiers, one being dedicated for the main engine and one for the SSDG's.
3.1.1 MAIN ENGINE LUBE OIL
3.1.2 AUXILIARY ENGINE LUBE OIL
3.2.0 FUEL OIL PURIFIERS
One major complaint about the purifiers is the spacing between the units. The engineers feel the units should be spaced farther apart to facilitate ease of servicing. It was also noted that the overhead hoist should be higher and act as an overhead crane with the capability of moving fore and aft as well as athwartships. As stated before, the purifier room needs to have more ventilation. There are crossovers for all the purifiers that allow them to take fuel from either fuel system.
The sludge tanks under the purifiers seem to be on the small side. The 1A/E said a larger sludge tank would make the system nicer, but there are space constraints on board the Sea Fox that prohibit this feature.
The general layout of the purifier room is good, aside from the purifier spacing.
3.2.1 HFO PURIFIERS
There are 2 HFO purifiers, with each running as clarifiers. Alfa-Laval installed the ALCAP electronics on the purifiers, which prohibit the purifiers from being run as purifiers. The basis of the system is the clarifier will extract the solids from the HFO, while the ALCAP electronics monitor the output of the purifiers for water. When water is detected, the purifier will shoot and discharge the water, along with a small amount of oil. Crowley will not purchase HFO if the specific gravity is more than .991.
The c/e feels the ALCAP electronics may be a little excessive, but has no complaints about the purifiers or their performance.
3.2.2 DIESEL OIL PURIFIER
There is one diesel oil purifier, located on the same flat with all other purifiers, on the side with the HFO purifiers.
There is only one evaporator on board the Sea Fox. It is a NIREX, single effect unit that produces approx. 24 tonnes/day of fresh water. It is rated at 30 tonnes/day, but at 24 tonnes it more than satisfies the needs of the ship.
The 1A/E would prefer to have a UV system to deal with water bacteria rather than a bromine system. The UV system is easier and safer, due to the bromine being caustic and the safety problems associated with handling.
5.0.0 COOLING SYSTEMS
Any machinery in the ER requiring fresh water cooling, is cooled by a central fresh water system. The temperature of this central fresh water system is maintained by a single salt water loop.
5.1.0 SALT WATER COOLING
The only salt water cooling in the ER is the salt water/fresh water heat exchanger.
5.2.0 FRESH WATER COOLING
All pieces of equipment that require cooling are cooled by one fresh water cooling loop, included the air charge coolers. This fresh water loop is usually maintained at 32 ˚C (90 ˚F) at the outlet of the salt water/fresh water heat exchanger.
6.0.0 HEAT EXCHANGERS
6.1.0 SALT WATER / FRESH WATER HEAT EXCHANGERS
There is a salt water/fresh water heat exchanger that keeps the fresh water loop at 32 ˚C (90 ˚F). The salt water pumps are variable speed and the fresh water pumps are two speed units. Usually the fresh water pump is run on high so the salt water pump will run at a lower speed. If the fresh water system temp goes up, the salt water pump speed will increase a little to bring the fresh water loop back to its operating temperature. The system automation allows this operation to happen automatically. The salt water side has recently had a backflush capability incorporated into the system. The engineers feel this was a very valuable addition to the system.
6.2.0 LUBE OIL HEAT EXCHANGERS
The lube oil heat exchangers are cooled by the central fresh water system.
All engineers are in agreement that there are not enough steam isolation valves in the ER. In order to work on any part of the steam system, the 1A/E says he usually has to shut down the boiler.
The 1A/E feels there should be a waste heat boiler for the SSDG's. Since one SSDG is always running, there is a lot of wasted heat going up the stack.
7.1.0 OIL FIRED BOILER
The oil fired boiler has a sludge burner on it that draws suction from a Pollution Abatement Tank (PAT). The major shortcoming with the system is the PAT tank itself. Slops are constantly being discharged to the PAT tank, with the tank rarely having time to settle out the water and the solid sludge. The PAT tank is a 12 tonne tank, which usually never gets filled over 9 tonnes. The bottom 2 tonnes of sludge is not fit for burning, leaving @ 7 tonnes for burning. When the boiler is operating, it burns 3-4 tonnes of sludge per day. In order to burn sludge, the inlets to the PAT tank have to be closed off and the tank allowed to settle out, and the slops pumped to another tank for holding during this period. If slops are being burned, there is not enough time to refill the PAT tank and let it settle out before the next port, where more burning will take place. The solution to this problem would be to add another tank to the slop system to be used as settling tank, with the additional tank being of equal or greater size than the PAT tank.
This boiler reportedly doesn't burn slops with a great deal of ease. The 1A/E would like to have a boiler that was a little more user-friendly than the one aboard the Sea Fox.
7.2.0 WASTE HEAT BOILER
There is a waste heat boiler located in the stack fidley, that draws exhaust from the main engine. The boiler has a separate steam drum, which is located on the same level as the waste heat boiler inside the stack.
8.0.0 BILGE, BALLAST AND FIRE SYSTEMS
There are 3 pumps that make up this trio: one is a dedicated bilge pump, the second and third are the ballast and fire pumps. All three pumps are connected to one common header, with its own sea chest.
8.1.0 BILGE SYSTEM
There are several deep well suctions throughout the ER bilge's, with the most commonly used suction located just aft of the main engine on the centerline of the ship. The bilge's are pumped to an oily water holding tank.
8.2.0 BALLAST SYSTEM
The Sea Fox does not have an automated system for ballasting. The Captain indicated there are two ballast tanks, one on each side of the ship. Ballast is pumped through this pipe, back and forth between tanks to level out the ship as needed.
The Sea Fox does have an automated trim system. During cargo operations, the list control system keeps the ship trimmed to a value the mate enters into the system.
8.3.0 FIRE SYSTEM
9.0.0 AUTOMATION AND CONTROLLERS
Most of the motor controllers and panels located in the ER were manufactured by General Electric. These controllers are a major sore spot with the ER crew, especially the main circuit board located in the control room. The C/E says the drawings are impossible to read and looking inside any of the electrical panels only adds more confusion to an already impossible problem. The C/E and 1A/E do not like the GE manuals or the electronics.
The control air system for the ER contains a system to dry the air. The system uses a refrigerant to dry the air as opposed to a powder. The 1A/E said this system works well and requires very little maintenance. Incidentally, this system was added by the ships engineers. The control air system is separated into main engine control air and general control air.
All of the ER valves are hydraulically actuated, with indicators in the ER control room.
Once again, the valve and level indicators need to be top-of-the-line. The engineers stressed that reliability in this area is a must.
10.0.0 SANITARY SYSTEM
The sanitary system on the Sea Fox is an enzyme system. The engineers like the system , citing there is little maintenance necessary so long as the ships crew refrains from using chemicals to clean the head located throughout the ship
11.0.0 STEERING GEAR
The steering gear system onboard the Sea Fox is a hydraulic ram type. The only comment about the steering gear is concerning access from the ER. To access the steering gear, the engineers have to go up three flights of ladders, cross-over and go back down two more ladders. The engineers expressed that a more direct path to the steering gear would be more favorable. The C/E doesn't have a high opinion of the controls for the steering gear, which were manufactured by Sperry.
12.0.0 AIR COMPRESSORS
There are four air compressors aboard the Sea Fox: two start air compressors, one control air compressor and one service air compressor.
12.1.0 STARTING AIR
12.2.0 CONTROL AIR
12.3.0 SERVICE AIR
13.0.0 DECK FEATURES
Both the C/E and 1A/E feel the self-contained container crane make the difference aboard this ship. If it weren't for the self-sustaining cargo capability of this ship, the Sea Fox would not be able to compete in the South American trade routes.
The captain indicated the stern thruster and the bow thrusters were not powerful enough. The captain said the bow thruster needed to be at least 2000 horsepower for it to be effective. The comment was also made about the stern thruster, stating it needed to be at least 2000 horse power as well.
14.0.0 CREATURE COMFORTS
A major shortcoming when the Sea Fox was built was the lack of storage space in the engine room. Most of the storage areas that are presently on the ship have been added by the crew over the years. The C/E feels there should be a dedicated place to store 55 gallon drums, as well as chemicals and cleaning gear. The storage for the 55 gallon drums would have to contain an overhead hoist or an opening in the overhead to lower the material from above. One other feature that would be a good addition would be quality cabinets and storage bins. Ideally these bins and cabinets would be installed when the ship was being built, or built in place by the shipyard once the ship was completed.
14.1.0 WORK SHOP
The engine department aboard the Sea Fox added an upper level to part of the workshop for storage purposes. There was a high overhead that allowed this addition, without affecting any other part of the work shop.
14.2.0 MACHINE SHOP
The machine shop is incorporated into the work shop.
There is a head forward of the control room, inside the ER.