I.          Preparation before test

1.1        During a sea trial, the seaworthiness, machinery and electrical installations of a ship are to be tested and its general performance and equipment is to be surveyed for compliance with the requirements of the classification rules, the flag State and international conventions.

1.2        Before a sea trial, the completed survey items such as main and auxiliary engines together with associated equipment, boiler system, bilge system, anchoring, rudder, life-saving appliances, fire safety equipment, navigation equipment, signaling equipment, communications, ballasting, watertightness, inclining test report, load line marking, tonnage measurement, oil pollution prevention, alarms and safety equipment are to be checked for confirming that outstanding items are removed and will not affect the sea trial.

1.3        The sea area for the trial is to be as restricted for the maximum design service. Temporary life-saving appliances are to be provided for the number of test personnel as required for ships operating in corresponding sea areas.

1.4        The sea trial program is to be agreed with the shipyard and the Owner. Test items are to comply with the classification rules or recognized standards (e.g. GB 3471 General Provisions for Mooring and Sea Trials of Sea-Going Ships) and to be approved.

1.5        Test items in a sea trial are usually completed by two surveyors. For vessels with less test items, the number of the surveyor may be reduced to one.

1.6        The Surveyor is to carefully record test data and issues for specific items which he is to witness.

1.7        Confirming that the ship’s draft complies with the design requirement for sea trial. The sea trial includes steering test and load test for the main engine. Confirm that the run-in of main engines is completed. The sea trial for tankers is at full draught. If the ship fails to go forward with maximum navigation draught at the speed corresponding to the maximum continuous revolution of main engine and maximum design pitch, the following methods can be used to demonstrate the conformity of the ship, regardless of its date of construction:

II         Maneuvering and Anchoring Tests

1.              Speed test

1.1       Test conditions are to be to the satisfaction of all parties concerned prior to the sea trial.

1.1.1     The test conditions may be further referred to IMO Resolution MSC. 137(76) and MSC/Circ.1053:

             Depth of test waters:   more than 4 times the mean draft;

             Wind force:                not more than Beaufort scale 2;

             Wave:                        not more than wave scale 4;

             Current:                     regular current;

             Draft:                        so far as practicable at design draft and where this is difficult to achieve, ballast condition may be accepted provided that trim is minimized and that special attention is given to effective submersion of propeller.

            Where test conditions are different from those above, appropriate correction of speed may be considered. Of which the correction formula for shallow waters is as follows

            △V/V=0.1242(Am/h2-0.05)+1-(tanh (gh/V2)^?

            Where: △V - correction on speed (m/s)  h - depth of water (m)  g - 9.81m/s2 Am- sectional area below draught  in mid position (m2)

1.2        Test details and procedure

1.2.1     The ship’ speed in each condition (specified rate of rotation of main engines) is measured according to design ahead conditions.

1.2.2     Range beacon method or any other effective measuring method (e.g. DGPS) may be used.

1.2.3     Prior to entering the area where speed is to be measured, each stable condition of main engines is to be achieved.

1.2.4     3 one-path tests are preferably to be carried out for each condition, and the speed is to be obtained as follows:

             V＝(V₁+2V₂+V₃)/4    (kn)

             Where:   V - average speed                                         V₁ - first one-path speed

                         V₂ - second one-path (return) speed                V₃ - third one-path speed

1.2.5     For twin-screw ships, additional speed measurement is recommended for propulsion with single screw.

1.2.6     The speed obtained is to be corrected for shallow waters, wind and wave.

2          Stopping test

2.1       Test conditions are the same as those in 1.1.

2.2       Test items and criterion, refer to IMP Resolution MSC.137(76) and MSC/Circ.1053.

2.2.1     The time used for stopping and full-speed backing, and the advance, transfer, time and bow angular deviation for natural stopping are to be measured respectively in specified half- and full-speed conditions.

2.2.2     Half- and full-speed natural stopping tests

a)   The ship sails at specified speed on a stable direct course as intended, and the initial course, speed and rate of rotation of main engines are to be recorded;

b)   A complete test runs from the stopping order being given to the ship nearly stopping its movement relative to water, and course, speed and distance are to be recorded every 30 seconds. Zero rudder angle is to be kept during test.

2.2.3     Half- and full-speed backing and stopping tests

a)   The ship sails at specified speed on a stable direct course as intended, and the initial course, speed and rate of rotation of main engines are to be recorded;

b)   A complete test runs from the stopping order being given, operation according to operational specifications for main engines to the ship nearly stopping its movement relative to water. Zero rudder angle is to be kept during test.

3          Turning test

3.1       Test conditions are the same as those in 1.1.

3.2       Test items and criterion, refer to IMO Resolution MSC.137(76) and MSC/Circ.1053.

3.2.1     Turning maneuverability, including maximum advance and maximum turning diameter, is to be measured in full-speed condition.

3.2.2     The ship sails on a stable direct course as intended for 2–3 minutes in full-speed condition, steered as required to 35° or maximum rudder angle. Time, speed and distance are to be measure once every 5 grades according to the course as indicated on the onboard compass, and a turning test is completed when the change of the bow heading angel reaches 540°. Of which the ship’s position is obtained according to the measured speed, course and time, with the speed being measured by log. The next test is to be carried out by reversing steering according to the same procedure. For small ships, the turning radius may also be measured by throwing wooden blocks.

3.2.3     For twin-screw ships, ahead and reversing turning tests are to be carried out alternately at specified speed to measure turning diameter.

4          Course stability test

4.1       Test conditions are the same as those in 1.1.

4.2       Test details and procedure

4.2.1     Rudder angle is to be kept unchanged to measure course change:

a)   The ship sails on a stable direct course as intended in full-speed condition;

b)   After being stabilized for 3–5 minutes, rudder is to be kept amidships, and compass readings are to be taken every 10–30 seconds for 3–5 minutes;

c)   One measurement respectively downstream and upstream.

4.2.2     a)    The ship sails on a stable direct course as intended in full-speed condition;

b)   The number of steering operations and maximum steering angle necessary for keeping the course unchanged is to be measured for 3–5 minutes;

c)   For twin-screw ships, the number of steering operations and maximum steering angle necessary for keeping the course unchanged is to be measured for propulsion by left and right single screw.

d)   One measurement respectively downstream and upstream.

5          Lateral thruster test

5.1       Test conditions are the same as those in 1.1 and in addition, the ship is in stopping (zero speed) or low speed condition.

5.2       Preparations before test

5.2.1     The fixing and control position of bow thrusters are to be examined;

5.2.2     “Zero” and “Maximum pitch” are to be adjusted in navigation bridge and both wings;

5.2.3     Thrust actions at all control positions are to be verified;

5.2.4     Thrust operation is to be examined at zero pitch for 30 minutes.

5.3       Test details and procedure

5.3.1     The ship’ speed at zero:

a)   Bow and stern lateral thrusters are operated respectively, changes of heading angle are to be measured and time recorded at maximum power, and the test is to last for 3–5 minutes;

b)   Bow and stern lateral thrusters are operated in combination, changes of heading angle are to be measured and time recorded at maximum power, and the test is to last for 3–5 minutes.

5.3.2     The rudder is to be kept at full rudder angel when the ship is at low speed to repeat the test of 5.3.1.

6          Steering test

6.1       For steering test, the main steering gear and rudder stock of vessels shall be capable of putting the rudder over from 35° on one side to 35° on the other side when the ship is at its deepest seagoing draught and running ahead at maximum ahead service speed and, under the same conditions, from 35° on either side to 30° on the other side in no more than 28 s. Relevant requirements on draft refer to 1.7 of Section BA7-1, Vol. II.

6.2       The steering test is to be carried out at maximum ahead service speed of the ship. Relevant requirements on draft refer to 1.7, II-B7-1 of the Instructions. Each power source, unit, control system and steering position is to be tested alternately.

            Steering procedure during test: each steering action to be kept for 10 seconds prior the next one:

      Amidship 0°                  ?   Hard starboard 35°

      Hard starboard 35°         ?   Hard port 35°

      Hard port 35°                ?   Hard starboard 35°

      Hard starboard 35°         ?   Amidship 0°

      Amidship 0°                  ?   Hard port 35°

      Hard port 35°                ?   Amidship 0°

6.3        Electrical motors or electrical hydraulic systems and their moving parts are to be examined for proper working. Voltage, current, oil pressure, steering time and maximum heeling angle are to be recorded. Time for changing rudder angle from 35° at one side to 30° at the other side is not to exceed 28 seconds.

6.4       The reliability of conversion from one control system to another and from one electrical hydraulic system to another for main steering gear is to be examined.

6.5       For the steering gear fitted with an energy accumulator, a test is to be carried out for shutting down oil pumps when the pressure of the accumulator reaches a specified value. The number or steering operations, time used and pressure reduction for conversion from full rudder at one side to the other side are to be measured.

6.6       Test of secondary steering gear.

            The test is to be carried out with the ship at half speed or a speed not less than 7 kn:

            Amidship 0°                  ?   Hard starboard 15°

            Hard starboard 15°         ?   Hard port 15°

            Hard port 15°                ?   Hard starboard 15°

            Hard starboard 15°         ?   Amidship 0°

            Amidship 0°                  ?   Hard port 15°

            Hard port 15°                ?   Amidship 0°

            Reliability of the secondary steering gear is to be examined during test. Time for changing rudder angle from 15° at one side to 15° at the other side is to be measured and recorded and the time needed is not to exceed 60 seconds.

6.7       Steering test of autopilot

            Each unit is to be operated alternately, course is to be set on gyrocompass and kept for 10minutes. Working condition of hydraulic systems of all components and their course-keeping capability and performance are to be examined for compliance with technical specifications.

            Convenience and reliability of conversion from autopilot steering to follow-up steering is to be examined.

6.8       Test of steering by using emergency power

            The main power supply is to be shut off and power supply converted to emergency power for steering (starboard and port) test, and the reliability of the emergency power is to be examined.

6.9       The Surveyor is to record relevant data, as specified, into classification documents.

7          Anchoring test

7.1       Prior to test, the Surveyor is to confirm the following:

7.1.1     Overload protection and adjusted-load protection is satisfactorily adjusted;

7.1.2     The depth of sea area for test is to be not less than 82.5m and where this requirement is not satisfied, alternative conditions for equivalent simulation will be considered.

7.2       Left and right anchors are to be dropped once respectively. The dropping is to be stopped for 3 times to check the reliability of brakes.

7.3       When the anchor is dropped, the anchor chain is to be fixed by deck chain stopper. Then the anchor chain is to be strained by low-speed reversing operation of the anchor winch or by making use of current or wind to check the reliability of the chain stopper.

7.4       Anchoring test is to comply with the following requirements..

7.4.1     In carrying out the trial of hoisting anchor by the windlass, a mean speed of hoisting one anchor from a depth of 82.5m to a depth of 27.5m is not to be less than 9m/min. Where the depth of water in allowable trial areas is inadequate, the deepest sea area in allowable trial areas is to be selected for trial.

7.4.2    Where the design anchorage depth is greater than 82.5m, the windlass is also to be able to hoist one anchor from the design anchorage depth to a depth of 82.5m at a mean speed not less than 3m/min. Where the depth of waters for the anchoring test is not adequate for the design anchorage depth, consideration may be given to accepting an equivalent simulating test. For example, dropping the anchor to the chain cable length of design anchorage depth and running astern to tighten the anchor chain cable, at that time, the windlass should be able to pull the anchor chain cable from a length of design anchorage depth to the chain cable length of 82.5m at a mean speed not less than 3m/min, and for the remaining chain cable length from 82.5m to 27.5m at a mean speed not less than 9m/min.

7.4.3   After recovery, the fitness of anchors to hull, proper positions of chain stoppers and reliable securing of anchors and chain stoppers are to be examined.

7.5       The following are to be inspected during test:

7.5.1     Passing of anchor chains and shackles through hawse pipes, chain stoppers and gypsies, bouncing and tumbling of anchor chains when passing gypsies resulted in hindering anchoring.

7.5.2     Efficiency of anchor washing devices.

7.5.3     Moving parts are to be checked for abnormal heating and striking.

7.5.4     Starting current and coming-aweigh current of anchor winches are to be measured.

7.6       The Surveyor is to record relevant data, as specified, into classification document.

III        Tests of Machinery, Electrical Installations and Automated System

1           Tests of main engines

1.1        The survey items and methods in respect to the tests of main engines are basically consistent with those for mooring tests stated above.

1.2        Sea trial conditions and test times for main diesel engines are given in Table 1.

Table 1  Sea Trial Conditions and Test Times for Main Diesel Engines

             In accordance with the requirements of IACS, the factory may lock the main engine fuel oil system under the rated power after bench test, i.e. 110% overload power may not be given onboard. The specification in the product certificate of the diesel engine is to indicate: “The fuel delivery system of the engines is adjusted that overload power cannot be given in service.” 

1.2.1     Each cylinder of main engines is to be balanced in normal output condition or rated condition. The deviation of main parameters of each cylinder from their mean values is in general to comply with:

            Compression pressure ≤ ±2.5%, maximum combustion pressure ≤ ±4%, exhaust temperature ≤ ±5% (high and medium speed engines ≤ ±7%)

            Parameters of main engines in rated condition are to comply with the values specified by the manufacturer.

1.2.2     Pumps, auxiliary equipment and sea chests serving the main engines are to be used alternately. The whole test process is to be continuous, with total downtime not exceeding 15 minutes.

1.2.3     For the main engines capable of burning heavy oil, operation by burning heavy oil and light-to-heavy oil conversion are to be tested to examine heavy oil preheating, automatic viscosity control, etc. The test is generally to last 2 hours, and operation by burning light diesel oil is in general to be the acceptance criterion for sea trial of main engines.

1.2.4     The working condition of shafting is to be examined. The clutch, if any, is to operate flexibly and reliably without skidding. The gearbox, if any, is to be examined for normal cooling and lubrication of shafting, and the temperature is generally not over 70℃ for sliding bearings, not over 80℃ for rolling bearings, and not over 70℃ for tail, intermediate and thrust bearings.

1.2.5     The stern tube is to be examined, and the level of gravity oil tank for tube shaft packing is to be checked.

1.2.6     The test time may be suitably reduced according to power and frequency of use of the engines.

1.2.7     After completion of the sea trial of main engines, crank deflection in hot condition may be measured and the deflection is to be not more than 3/10,000 piston stroke (mm) or the value specified in the main engine instructions. The foundation bolts, through bolts and lateral supports of main engines are also to be inspected for fixing.

2          Sea trial of main propulsion machinery

2.1       The lowest stable speed of main engines is to be measured. The main engines are to be tested for different speeds to confirm compliance with the relevant requirements of Chapter 9 of PART THREE of CCS Rules, and the lowest stable speed values are to be recorded.

2.2       The rotation reversal of reversible main engines is to be tested. Restricted by tethers at quay, the reversing time is to be measured during sea trial. The time from beginning of reversal to beginning of reversed rotation of main engines is to be checked with main engines at the lowest stable speed, and the time used for reversal is to be not more than 15 seconds as required in the Rules.

2.3       Ahead and reversed running tests of reversible gearbox. The time for conversion from ahead (or reversed) running to reversed (or ahead) running is to be not more than 15 seconds at normal conversion speed (not less than 50% of rated speed of main engines).

2.4       Reversal test of adjustable pitch propeller. The time for change of 1/3 positive (negative) full-load pitch angle to 1/3 negative (positive) full-load pitch angle is to be not more than 15 seconds at rated speed of main engines.

3          Overhaul items after sea trial

3.1       After the sea trial, the door of the crankcase is to be opened within the specified time to check the temperature of the main bearing and crank pin bearing and measure the crankshaft deflection in hot condition for compliance with the instructions or a recognized standard.

3.2       After the sea trial, the fixing of through bolts and lateral supports of main engines is to be examined in cold condition. All foundation bolts of main engines, reduction boxes and shafting bearings are to be re-fixed according to calculated moments, and chocks are to be re-knocked in and secured by spot welding.

3.3       One set of cylinders of main engines is generally to be overhauled to examine moving parts.

3.3.1     The cylinder sleeves are to be examined for wear and for B&W diesel engines, mesh on sleeves is to be clearly visible.

3.3.2     Crosshead bearings, connecting rod bearings and main bearings are to be examined for excessive wear and scratches, and running-in traces are to be symmetrical.

3.3.3     Pistons are to be examined for abnormal condition of head and normal carbon accumulation, and piston rings are not to be jammed.

3.3.4     Air valve inlet and seat are to be examined by a reflecting glass for smoothness.

3.3.5     Crankcase sump is not to contain alloy power, welding slag, etc.

3.3.6     After re-assembling, a running test is to be made for half an hour in mooring condition to examine the re-assembled condition.

3.4       Overhaul of secondary engines may be determined according to their actual condition, generally a set of cylinders is to be overhauled.

4          Sea trial of automation systems

4.1       Sea trial of ships with automated engine room

4.1.1     For ships with program-controlled main propulsion machinery or remote control or automated systems, or ships with unmanned engine room, various control tests of main engines within the scope of all operational conditions are to be carried out in navigation bridge (if fitted, including central control station). Diesel engine propulsion is to be tested according to the procedure as shown in Figure 1, and powered adjustable pitch propeller propulsion is to be tested according to the procedure as shown in Figure 2.

Figure 1  Test Procedure for Control System of Main Diesel Engines

Figure 2  Test Procedure for Single-Handle Control System of

Powered Adjustable Pitch Propeller

                      Explanations for Figures 1 and 2:

1.      The speed is to be stable before change of each control condition during test.

2.   The speed of main engines during test is to be full, medium, low and dead low as in narrow waterways or harbor.

3.   The numerals in the Figures refer to time, in minutes.

4.   At dead low speed, full rudder operation is necessary where the symbol ○ is marked.

5.   The control handle is to be pushed to the required position as quickly as possible where the symbol ? is marked.

6.   When medium speed advancing is controlled from the control station in navigation bridge, the power supply (electricity, compressed air, oil pressure) for remote control system is to be shut down for 2 minutes where the symbol ○ is marked, so as to examine the main engines for any danger or abnormality due to loss of control power.

7.   Where the symbol ?? is marked, main engines are to be stopped by the emergency shutdown device.

8.   Where the symbol × is marked, the running of shafting is to be stopped.

      Note: For the control system of multi-engine single propeller ships and the non-single-handle control system of adjustable pitch propeller ships, the test method and time may be adjusted as necessary according to the above Figures.

4.1.2     Reliability test of unmanned engine room of ships having AUT-0 class notation

4.1.2.1  Test conditions: alarms and indication systems are to be normal. Any alarm point which may be removed is to be removed in time. Normal alarms may be distinguished as appropriate. Main engines are to be controlled from navigation bridge at a speed under normal power output. Main engines are to be operated by burning heavy oil. A diesel generating set is to be operated (heavy oil is to be used where possible), while the remaining sets stand by. Exhaust boilers are to be used, while secondary boilers stand by. One fuel oil separator and one lubricating oil separator are to operate. One of the pumps serving main and secondary engines is to operate, while the other ones stand by. Seawater converters are to operate continuously, while air compressors automatically stand by.

4.1.2.2  The unmanned engine room can be tested only after the above test conditions are confirmed together with the Surveyor, Owner and shipyard personnel. The whole test process is to last at least 4 hours. During test, only 1 or 2 persons are allowed in the engine room for observation and the Surveyor is to make inspection tour in the room. The working condition and parameters of all equipment used in the engine room are to be within the permissible scope.

4.1.2.3  Several possible normal alarms are allowed, but no alarm for any major failure (which may result in speed reduction or stop of main propulsion machinery, failure of adjustable pitch propeller, boiler flame failure or failure of steering gear) is allowed. The number and scope of allowed alarms are to be agreed with the Owner and shipyard prior to test. After completion of test, all parameters and alarm indications are to be printed out.

4.1.2.4  A failure is to be simulated at medium speed to automatically stop generators for checking automatic start and automatic power supply of standby generators and for checking automatic sequential start of pumps.

4.2       Exhaust boiler test

            Exhaust boilers are to be tested for automatic adjustment of feed water and adjustment of surplus steam valves. The automatic adjustment of exhaust gas throttle is to be checked.

5          Sea trial of electrical installations

            Test items may be completed basically during mooring test. However, some items may be arranged for sea trial according to actual conditions of the shipyard.

            When main engines are in operation, failures of the electrical installations on board may arise due to loosening wiring, displaced parts, etc. caused by vibration. The purpose of sea trial of electrical installations is verification of their working reliability at sea. Therefore, the survey is to be concentrated on examination and monitoring of working condition of electrical installations, paying attention to the following in general:

◆  Normal working of the installations, normal display of monitoring instrumentation;

◆  Abnormal vibration;

◆  Abnormal noise;

◆  Abnormal surface temperature;

◆  Measurement of working current;

◆  Measurement of hot insulation resistance of each current.

            The items for electrical installations are in general to be tested in conjunction with examination and test of other specialized machinery installations which are mainly:

5.1       Examination of motors and control of essential pump sets

5.2       Examination of generators in normal sailing condition

5.3       Alternate operation of generating sets for checking imbalance between loads in each phase. The start of the motor having the maximum power is not to cause loss of power.

            Speed range of main engines having rated power output from shaft-driven generators, and automatic start of standby generating sets when rated power output is lost.

5.4       Anchoring test, measuring starting current, working current in each order, coming-aweigh current, voltage and rotation of motors.

5.5       Steering test

            Communication test between navigation bridge and steering gear room, check of rudder angle, changeover of power source and control for steering gear, measurement of steering time, etc.

5.6       Power loss test

            Running generators are to be stopped, standby generating sets are to automatically start and switch in. Where standby generating sets do not automatically start within the specified time, emergency generators are to automatically start and switch in and when standby generating sets automatically start and switch in, emergency generators are to automatically switch off.

5.7       Sound effects of alarms and communications are to be checked so far as practicable in normal sailing condition.

5.8       For tests of navigation aids and communications, see Part III-C of the Instructions.

6          Other tests

6.1       Exhaust boilers are to be tested for opening and closing of safety valves in rated condition of main engines, according to the same requirements for safety valves of secondary boilers. The flexibility of manual handles is to be checked.

6.2       Sea trial items for prototype ships of same type

            Prototype ships of the same type are to be subject to tests of torsional vibration, axial vibration and whirling vibration. This may be done by specialized personnel and confirmed by the Surveyor.

II-BA7                 航行试验

                      Sea Trial

序号                     分目录

No.                    Sub-contents

BA7-1                    一般要求

                     General Requirement

BA7-2                 船舶性能和设备试验

                 Maneuvering and Anchoring Tests

BA7-3              机械、电气设备及自动化试验

       Tests of Machinery, Electric Installations and Automated System