As a Senior Engineer, how do you prepare for dry-docking?
(a) Before months ahead
(b) just few days ahead entering into dry dock.
(C) Before just few hours before entering into dry dock
- Dry docking surveys done 2 times in 5 years cycle, called annual docking and special docking survey.
- Special survey is usually carried out every 5 years interval.
- As a Senior Engineer the following prepared before dry docking, based on the PMS, Defect lists, and survey items.
- Repair items report to head office for approval
Before months ahead
- Necessary plans, drawings, instruction manuals and service records of previous docking collected and kept ready.
- Repair lists for both ship yard and ship’s staff listed and grouped.
- According to repair lists, hand tools, special tools and spare parts checked and prepared for readily available.
- Needful store and spare parts requested to get in time.
- Issue instructions for safety, fire precaution and pollution prevention.
- Issue assignments for work to be done before entering dry dock and to be done during docking period after discussing with all senior engineers and the office.
- Inspect and test emergency light, emergency generator, emergency fire pump and fire extinguishers, and all are kept in good working condition.
- Engine room personnel trained proper using of these equipment
- Check Shore power connection box and prepared for ready to use.
Before a few days
- Before entering the port, E/R bilge wells; tank top hosed down and cleared
- Required trim and draughts corrected by ballasting or by transfer F.O. The load to be kept in minimum if possible.
- Job lists for both shipyard and E/R staff grouped and label all repair items.
- Take and record M.E crankshaft deflection. Check and test Emergency generator, shore power connection box for readily.
- Prepare cooling water connections for fridge and air conditioning plants.
- International shore connection for firefighting made ready for emergency use.
Before few hours
- Top up F.O tanks and record all tanks’ sounding. Press up air bottles and tight shut
- Before entering dry dock, explain procedures and assigned duties to E/R personnel. (G/E stopping, shore power and cooling water connections commenced time etc. to be recorded)
- Shut down boiler, release steam pressure through easing gear.
- When shore power taken, stand by on shore connection box and main switchboard.
- Check emergency generator and shore power supply voltage and frequency
- Instruct all engine room personnel to use stores and spares without wasting.
- Instruct all engine room personnel to follow dockyard fire and safety instruction and provide fire-watch duty day and night.
As a Chief Engineer, how to carry out following preparations for dry-dock.
(a) Preparing of Dry-dock repair list.
(b) Preparation prior to dry docking
(c) Before flooding
(a) Preparing of Dry-dock repair list
1. Maintenance job and repairs for auxiliary machinery, All rust pipe and fitting
2. Maintenance, overhauling, repair job for valve, all ER pump, deck machinery system, electrical system
3. Needful store and spare request to get in time
4. After discuss with superintendent, decide job lists for both shipyard and E/R staff grouped.
(b) Preparations Prior to Dry-docking
- Before entering the port, E/R bilge wells; tank top hosed down and cleared
- Required trim and draughts corrected by ballasting or by transfer F.O. The load to be kept in minimum if possible.
- Job lists for both shipyard and E/R staff grouped and label all repair items.
- Take and record M.E crankshaft deflection. Check and test Emergency generator, shore power connection box for readily.
- Prepare cooling water connections for fridge and air conditioning plants.
- International shore connection for firefighting made ready for emergency use.
(c) Checks before Flooding
1. Before flooding, explain procedures and assigned duties to E/R personnel.
2. Check all repair and underwater jobs in accordance with repair list.
3. Check all underwater fittings such as
(a) Secure plugs of DB tanks
(b) Fitted all sea inlets and sea chest granting
(c) Correctly fitted echo sounder and logs
(d) propeller and rudder are clear from any obstruction
(e) Any sign of leakage for stern tube
(f) Check ICCP anode fitting and its watertight cable duct on the hull correctly fit.
4. Check all repaired overboard valves are correctly fitted in place
5. When dock flooding reaches sea chests and sea valves, stop process and open each sea valve and check for any leakage.
6. All repaired pipes and stern tube must be checked for leakage.
7. Purge air from all sea chests, cooling seawater pumps, run the pumps and check pressure.
8. Ensure emergency generator is readily available.
9. Test run ship generators, until satisfactory, and cut out shore supply, cut in ship generator, disconnect shore connection,
10. If required, emergency generator power can be used before starting the main generator.
11. Once flooding is in process, a responsible engineer go to bow thruster and steering gear room to check water tightness.
12. Check as per check list and check list to be finally signed by master. Master must sign authority for flooding certificate.
13. Instructions given to E/R personnel to stay vigilant while undocking.
14. Continuously keep checking the water tightness of the engine room throughout the process.
15. If any kind of water leakage is found, inform immediately to the officer-in-charge.
(a) As a Senior Engineer describe about the definition of Permit to Work.
(b) Explain about the items consists in PTW.
(c) Describe about the work of the Person In-charge.
(d) Describe about the duty of Individuals at the work site.
(a) Definition of Permit to Work
A permit to work system is a formal written system to control certain dangerous job.
- PTW determines how that job can be carried out safely.
- The issue of a permit does not, by itself, make a job safe. Need preparation to carry out safely.
- Foreseeable risks thought use suitable precautions.
(b) PTW consists of the following items
1. Location of the work
2. Exact nature and scope of work
3. Number of workers and special tools involved
4. Results of any preliminary tests undertaken
5. Safeguards that need to be taken during operation
6. Validity period (should not exceed 24 hours)
7. Signatures of Authorized person and Responsible person.
8. Time of completion (to fill up when the work completed)
9.Authorized person signed for cancellation.
(c) Work of Person in charge is
1.Discuss job fully with permit issuer
2. Give adequate instruction to working party
3.Permit is posted at work site
4. Precautions maintained throughout work activity
5. Supervise working party to stay within work area
6. Communicate clearly at all time to the working party
7. Take information from working party and determine status of condition for any hazards
8. If circumstances change, work must be stopped. Inform and take advice from authorized person
9. Adopt action required to take in the event of an emergency.
10. On completion or suspension of work, site is left in a safe condition and inform to permit issuer
(d) The duty of individuals at the work site is to ensure that,
1. Good understanding of permit to work system where they work.
2. Do not start any work until PTW permit has been properly issued.
3. Received a briefing and adequate instruction from Person in charge
4. Communicate at all time to person in charge and inform situation of work.
5. Inform immediately if circumstances change and consult with person in charge.
6. Must know emergency procedure and how to evacuate safely after receiving signal from person in charge.
7. When they stop work, any equipment they are using is left in a safe condition.
As a Chief engineer
(a) What action would you take when stern tube seal leakage at sea, cause and remedy?
(b) How to continue the voyage and how to repair in port?
(c) How to claim for insurance?
(a) Stern tube seal leakage
1. Misalignment of bushes
2. Poor material, design of liner and seals
3. Contaminated oil supply with foreign materials
4. Fishing net, rope and similar material entering into seal due to defective rope guard.
5. Electro static pitting on shaft due to defective shaft earthing device.
6. Prolonged low speed operation, in which hydrodynamic oil film could not attain.
Remedies
1. Keep good alignment of bushes.
2. Use good material and an improved seal design.
3. Always maintain L.O level due to draught condition.
4. Keep sufficient aft peak tank water level.
5. Use good design of rope guard.
6. Keep earthing device in good order.
(b) Action to be taken at sea to continue the voyage
When stern tube seal leaks at sea, minimized as possible. To continue the voyage, following actions are to be taken.
1. Correct the vessel trim, as possible as minimum astern, to certain allowable trim
2. Use more viscous oil (e.g. Cylinder oil)
3. Use lower header tank. If not possible, reduce the oil pressure-head by using a ‘temporary header tank with flexible hose to obtain only slight pressure head above SW pressure.
4. If required, reduce rpm to avoid boundary lubrication.
Repair in port
1. Repairs or renewal of aft seal done either in dock or afloat.
2. If vessel is due for dry docking survey or a dry dock facility is available, arrange to enter dry dock and renew both seals.
3. If dry dock facility is not available, renewal of shaft seals done by Bonding method in port without removing propeller and tail shaft.
4. Necessary vessel trim by ahead until propeller shaft exposed to correct position above water level and to set up “scaffolding.
5. Renewal of sealing ring done by cutting and joining it on shaft with special tool and high temperature bonding method.
(c) Insurance Claim
1. When leakage occurs, inform to head office or owner through captain.
2. When arrive in port, invite Class Survey and Underwriter Surveyor.
3. survey damage and by their recommendation, repair to be carried out as per Class requirement.
4. Quotation of repairs and repair cost submitted to Underwriter Surveyor to negotiate for any reduction appear necessary.
5. Both surveyors will survey the repaired work when completed.
6. For insurance claim purpose, repair cost and bills endorsed by Underwriter Surveyor, but exclude transportation charges.
7. For insurance claim purpose the following items are necessary.
(a) Damage report
(b) log abstracts
(c) Damage report form for insurance claim
(d) Class Surveyor recommendation
(e) Repair bills endorsed by Underwriter Surveyor
(a) Differentiate between water and oil lubrication of stern tube.
(b) How to measure stern tube wear down for Oil lubrication type.
(c) What are the checking points to be done to get correct data?
(a)
| Nature | Oil Lubricated Stern tube | Water Lubricated stern tube |
| Cost | High | cheap |
| Friction | less coefficient of friction | high coefficient of friction |
| Lubrication | hydrodynamic lubrication | cannot obtain hydrodynamic due to poor viscosity of water |
| Measuring | use poker gauge at aft end seal | use poker gauge at aft end seal |
| Clearance | 0.0015-0.002 mm of shaft diameter | 0.003-0.004 mm of shaft diameter |
| Wear limit | 2-3 mm of shaft | 9-12 mm for large diameter shaft |
| Bearing material | Grey cast iron with centrifugally lined white metal | Lignum vitae reinforced rubber staves on liner |
| Bearing length | Ford end=0.6 x shaft dia Aft end = 1.5 x shaft dia | Ford end = 1 x shaft dia Aft end = 4 x shaft dia |
| Sealing arrangement | Fit inboard & outboard seal Inboard seal prevent LO leaking Outboard seal prevent SW leaking | Allow SW enter to cool & lubricate Slight amount of water pass through stuffing box gland for cooling |
| Shaft | Without sleeve | Continuous length of gun metal liner is shrunk fit to tail shaft between propeller & point beyond stuffing |
| Construction | Cast iron construct stern tube pressed into stern frame Two white metal bearing bushes press into stern tube | Cast iron construct stern tube pressed into stern frame Forward end flanged to aft bulkhead Wood liner insert between them |
(b) Measurement of wear down for Oil Lubricated stern tube
Before taking measurement, read maker instruction manual and collect previous docking records and data related to tail end shaft and stern tube bearing.
1. Working aloft permit and all other necessary permits done and follow them.
2. Remove rope guard. Measure wear down or shaft drop by depth micrometer or poker gauge.
3. Insert gauge at one of oil plug holes of aft seal housing after removing oil plug.
4. Measurements take at same radial positions at 90˚ intervals of shaft.
5. Some makers provide measuring points at top and bottom.
6. Record measurement data in record sheet and on table placed in poker gauge box for next time quick reference.
(c) Checking points to be done to get correct data
1. Measuring taken as per maker instruction or previous record methods.
2. Measuring taken at same position of shaft. e.g.
Method (a) Turn Engine No.1 unit at TDC
Method (b) Turn Propeller blade No.1 reference mark
Method (c) Turn marking on the shaft and marking on the hull to be coincided
3. Markings on gauge and seal housing coincided.
(a) Sketch and describe Stern tube bearing L.O. arrangement, couple with high and low tanks
(b) If shaft seal leakage occurs, how will you manage to keep on steaming the ship before repair?
(a) Stern tube bearing L.O arrangement
Tankers and other ships with large changes in draught fitted with two oil header tanks for either fully loaded or ballast conditions.
- Circulation and cooling system for inboard seals, unlike those at outboard end, cannot dissipate heat to surrounding water.
- This circulation may be obtained by natural convection.
(b) In the event of loss of oil
The serious oil leakage from aft seal can be minimized and continues the voyage as follows
1. Tip the vessel to certain allowable trim.
2. Use more viscous oil (e.g. cylinder oil).
3. Reduce oil pressure head by using a temporary header tank, normally oil drum (200 Ltr capacity) is used and connected to the system by a flexible hose. This drum must be arranged at certain vertical position to ensure only a slight pressure head is exerted.
4. In large vessel, lower header tank can be used instead.
5. Reduce R.P.M if required
In the event of seawater ingress, to continue the voyage,
1. Use higher oil header tank.
2. Slow down the shaft revolution.
