Cait Manual e

MANUAL

CAIT

(Computer Aided Inclining Test)

II / 1995

HOPPE Bordmesstechnik GmbH


Hoppe Bordmesstechnik Page 1CAIT 2/95

Contents

Introduction............................................................................................................2

2 Start of Software ............................................................................................4

3 Survey of menu functions ..............................................................................6

3.1 FILE .............................................................................................................63.1.1 EXIT..........................................................................................................................63.1.2 SHOW TEST.............................................................................................................6

3.2 SETTINGS....................................................................................................73.2.1 Seawater Density .......................................................................................................73.2.2 Tankwater Density.....................................................................................................7

3.3 WINDOW .....................................................................................................83.3.1 SHIPGRAPHICS.......................................................................................................83.3.2 SHIPDATA ...............................................................................................................93.3.3 PLAUSIBILITIES...................................................................................................103.3.4 START AUTOMATIC TEST.................................................................................11

3.4 ALARM LIST ..............................................................................................11

4 User input and its indication .......................................................................12

5 Performance of an Inclining-Test ...............................................................13

5.1 Preconditions .............................................................................................135.1.1 Draught values.........................................................................................................145.1.2 Preset values for the test ..........................................................................................14

5.2 Start of Test ................................................................................................14

5.3 Automatic control of test progress .............................................................15

5.4 Print of report ............................................................................................15

5.5 Test Stop.....................................................................................................15

6 Calculation Basics ........................................................................................16

6.1 Draught ......................................................................................................16

6.2 Displacement..............................................................................................17

7 RS485-Interface............................................................................................17

8 Connection of printer...................................................................................17

9 Annex.............................................................................................................18

9.1 Print of example .........................................................................................18



Introduction

The program CAIT is to support the navigators in determining the actual shipstability. For determination of the actual GM value of a ship an inclining test iscarried out in the course of which the ship is inclined by a certain angle. When thedisplacement, the moment producing the inclination and the finally achievedinclining angle are known, the value GM can be calculated acc. to a simpleformula.

In order to automate this inclining test, the Hoppe system ”CAIT” was designed.The system consists of several components which, when working together, cancarry out automatically a complete inclining test.

• In order to incline the ship by a certain angle, a quantity of water, which can bedetected exactly by means of sensors, is pumped between two opposite tanks bymeans of the Hoppe Anti-Heeling plant. When doing so the angle of the shipand the quantity of water pumped are continuously detected and showngraphically. From the geometric positions of the tanks and the water quantitythe inclining moment on the ship can be calculated and the actual GM can bedetermined by the angle.

• The analogous measuring values of tank contents and angle are detected by ameasuring device for the tank contents.

• In order to detect automatically the displacement as well, the draughts of theship are detected by means of two draught sensors, one forward and one after ofthe ship. The middle draught should be read from the pier by the crew andmanually input, through an anglemeter calibrated for list the opposite middledraught will be calculated. The trim resulting will calculate with the bothdraughts sensors forward and aft. From these values displacement can bedetermined by means of a table. Moreover, these values are pre-processed bythe measuring device of tank contents. A PC program which is connected withthe anti-heeling plant and the tank contents plant by means of serial interfacesserves for control of the components mentioned and for detection andindication of the measured values. This program controls the heeling pump andthe corresponding valves acc. to a determined scheme in order to make possibleautomatic progress. During the test the measure variables List and GM areshown graphically. Moreover, during the test a plausibility check is carried outcontinuously for the decisive measured values, so a test is interrupted in case ofdefective sensors.



• For this control the inclining angle is detected by two independent emitters. Ifthere is a considerable discrepancy between both sensors, the automatic test isinterrupted.

• Moreover, certain min. resp. max. values are permanently monitored during thetest. Among others, these are the draughts, sagging/hogging, list, tank contentsof the stability tanks as well as different time conditions.

Despite of the safety precautions described the operator isobliged to check all values measured automatically for deviationsat regular intervals, e. g. by visual check of the draughts and thetank levels.Additional the middle draught must be manually input by readingit at the shore side.



2 Start of Software

The CAIT program is a program which can be started under WINDOWS 3.1,WINDOWS FOR WORKGROUPS 3.11, WINDOWS 95 as well as WINDOWSNT V3.5 and 4.0.

We expect you to be familiar with starting and handling of WINDOWS and werefer you to the corresponding documentation of Messrs. MICROSOFT.Nevertheless we shall explain in short handling at the corresponding subjects.

In order to start the program you look for the group ”CAIT” in the Windowsprogram manager and click twice (double click) on the symbol named ”IncliningTest CAIT”.

Immediately the main window of the program with the logo ”CAIT is loading”will open. After a short starting phase a ship graphic will be shown in the mainwindow which shows the most important measuring points and their actualmeasuring values which include the inclining angle, the draughts at the draughtmarks and the tank contents.



Note: if the spaces for the measured values in the graphics remain empty formore than 20 s, connection to the tank measuring plant is interrupted. If so, checkfunctioning of the tank measuring plant and cabling.



At the upper edge of the main window you find a menu bar indicating the mostimportant functions. The menus can be opened by means of the mouse button,from the selection list appearing then individual items can be selected by themouse as well.E.g. in order to terminate the program, choose the first item ”FILE. By clicking onthe sub-item ”EXIT” you leave the program after a safety enquiry.

3 Survey of menu functionsAs a rule Windows programs are controlled by the mouse via switching surfacesand menu bars. Nevertheless all menu items can also be controlled by thekeyboard. Via the key ALT and a letter key all menu items can be selected. Theletter key to be used is underlined in the menu name (as a rule the first letter).

E.g. choose the menu ”FILE” by the key combination ALT + F. When doing sothe ALT key is to be pushed down first and kept down until you have pushed theletter key. (By the way you can terminate a menu opened by the key ESC).

3.1 FILE

3.1.1 EXITThe program is left when this function is actuated. However, the program is leftonly after an additional safety enquiry.

3.1.2 SHOW TESTBy means of this function you can look at test results of former inclining tests in areport window and have them printed if required. If selected the window openswith the results of the last test. These results and those of preceding tests arestored in a data bank of the hard disk of the computer. By clicking on the arrowsin the right part of the window you can walk through the results of the tests stored.Click on ”PRINT”, if you want such a report to be printed. ”CLOSE” serves forclosing the report window.



3.2 SETTINGS

3.2.1 Seawater DensityHere enter the actual seawater density. Only if this is correct, draught and thusdisplacement of the ship can be calculated exactly.

3.2.2 Tankwater DensityFor determining the contents of the stability tanks density of the water containedin these tanks must be entered. Here enter the density in the dialogue windowopening.



3.3 WINDOWA selection of the menu function described here opens another window. Thesewindows contain additional information and can be closed again at any time byclicking on the right-hand upper edge of their frame.By means of the mouse all windows can be arranged at random within the mainwindow. For this purpose the title line is to be fetched with the mouse buttonbeing pushed down. If the mouse is moved now, you shift the window ”fetched”to the place desired.

3.3.1 SHIPGRAPHICSWhen starting the program this window is opened automatically and arranged atright hand. It shows the most important measured variables of the plant. Here youfind the draughts at the draught marks FWD, MID and AFT, the inclining angle,trim between the draught marks in meters and the displacement in tons calculatedfrom these values.In the lower window range the status of the heeling pump and of both stabilitytanks is shown graphically. Tank contents of both tanks are summed again in themiddle of the graphic. During pumping process between both the tanks this summust not change considerably.

Trim between the Draught Marks

Draught Mark FWD

List

Draught Mark MID SB

Draught Mark AFT

Tank content in the stability tanks

Sum of the content in the tanks PS+SB

Status Heeling-Pump

Displacement



3.3.2 SHIPDATA

Here you find more details concerning draught and the parameters derived. Thedraught values measured by means of pressure sensors are converted to thedifferent places of the ship and are indicated here. Additionally to the valuesindicated in the ships graphic you can find here the draughts at the leads incenterline of the ship, trim between the leads, sagging midships as well as thepreset values for density of sea water and tank contents.



3.3.3 PLAUSIBILITIESAs already indicated in the introduction this program carries out continuously acheck of the sensors by means of comparisons between redundant measuredvalues.If the deviations exceed a limit value, alarm is indicated in the alarm list. If so,you can see in this window which measured value deviates from the real value.For verification purposes the difference between both inclining sensors as well asthe difference between the trim from the draughts and the separate angle sensor fortrim are calculated. These both differences are continuously monitored by thealarm system and produce an alarm, as already mentioned, when a limit value isexceeded.



START TEST

3.3.4 START AUTOMATIC TESTAt this selection preparations for a automatic inclining test are started. A check listappears which is to be filled in by the user. Thereafter the test starts in the courseof which different inclining angles are applied by remote control of the heelingpump. After termination of the test the test result is stored in a data bank andshown on the screen for printing. For further information see chapter”Performance of a test”.

3.4 ALARM LISTMonitoring of the sensors belongs to the most important safety functions of thisprogram. If there are deviations between the sensors or if limit values areexceeded, automatic determination of stability is not possible and must not bepossible. In such a case there will be a corresponding remark entered in the alarmlist. The alarm list opens when clicking on the corresponding item of menu. Allalarms occurred since start of the program are indicated in chronological order andare provided with an alarm number. If the preconditions for the alarm are nolonger complied with, the remark ”NORMAL STATE” appears with the samenumber below the alarm indicated. By actuating the switching surface”REFRESH” such alarms are quitted and eliminated from the list.

The bell symbol in the right-hand upper edge enables the alarm list to come to thefore automatically in case of alarm. For this purpose click on the symbol by meansof the mouse button.

You can close the alarm list window by actuating the switching surface at theright-hand upper edge of the list window or by means of a double-click on the left-hand upper edge with the minus symbol.



4 User input and its indicationFor many measuring variables the user can enter manually values for correctionpurposes. For this case you have to make a double click with the mouse button onthe respective field. Then an input window opens.Here you can enter the corrected value.

The measuring value preset manually is provided with a star (*) in all windows inorder to show that this measuring point is in user input mode. All parametersderived from this measuring point appear in blue, whereas the parametersmeasured by the sensors are shown in black. This difference in colour showswhich values are not detected automatically. E. g. also the water densities whichmust principally be entered manually belong to this group!

In order to eliminate user input again you can remove the cross in front of theinput value (mode user input) in the user input window by clicking-off.

Name of the measurement

Offline: automatic measurement not possible,otherwise value from Sensor

Manual input modus

Input field



5 Performance of an Inclining-Test

5.1 PreconditionsFor exact determination of the GM value different preconditions are to becomplied with which the user should observe exactly. In order to guarantee thatyou do not fail to notice any important item, the user has to fill in a check list priorto starting the test. All items must be confirmed by mouse-click individuallybefore a test is possible. Moreover, the program checks all data connections andmeasuring values. If in the course of this check faults or deviations are detected,test preparations are stopped and a corresponding note appears. Depending ontheir cause the corresponding problems must be solved prior to starting a new test.Prior to starting a test, make sure that the anti-heeling plant is switched to stabilitytest mode and is on automatic operation. Moreover, it is a precondition that thereis sufficient ballast water in the stability tanks.In order to start a inclining test choose the menu item ”Start Test - Automatictest”. Thus the a/m system check is carried out and the window with the check listappears.Apart from the check list described above this window contains some measuringvalues at which the user shall have a critical look and which should be corrected ifrequired (draughts, displacement, densities etc.), as well as preset values for testprocedure.



5.1.1 Draught valuesThe instantaneous draught values must be checked and confirmed. If the valuesstated in this window deviate from the real values, preset values entered by theuser must be used for the test. For this purpose have a double-click on the value tobe changed and enter the true value in the window. In such a case it must beobserved that the draught values depend on each other. After manual input youhave to check carefully all other draught values again, or enter all draught valuesmanually.

5.1.2 Preset values for the testThe automatic test procedure permits some values preset by the user. Selection iseffected by clicking on the corresponding fields:

Testwinkel /Test-AngleHere state the desired inclination for the test. In the course of the test the ship willbe inclined to both sides from its instantaneous position. In general it can be saidthat exactitude of GM determination increases with increasing test angle. Sochoose the largest angle possible for the instantaneous situation.

erwartetes GM / expected GMThe GM value is graphically shown in a coordinate system. For a reasonable scaleof the GM axis this value must be entered. However, it does not influence the testresult!

Pumprichtung /initial Heeling directionHere you can determine the pumping direction with which the test starts.

additional inputsPort, voyage and operator is indicated in the report with the test results. It isrequired to enter these data before the test can start.

5.2 Start of TestIf preparations for the tests are completed as described above, the real incliningtest is started by actuating the switching surface ”START”.In addition to the ships graphics two further windows open, i. e. a coordinatesystem for GM and list and a table for showing intermediate results.Below this table you find a switching surface ”STOP”, by means of which atest procedure can be stopped at any time.When the test is terminated or stopped, the coordinate system and the table can beclosed by clicking on ”CLOSE”.



5.3 Automatic control of test progressIf the pumping direction chosen is towards starboard, an automatic test will becarried out acc. to the following scheme:

1. Pumping from start position towards starboard by the inclining angle preset.

2. Stabilization phase of 2 min., thereafter calculation of first intermediate result.

3. Pumping towards port up to start angle.

4. Stabilization phase as item 2.

5. Pumping towards port up to start angle plus the inclining angle preset.


7. Pumping towards starboard up to start angle.


9. Calculation of min. GM and opening of the report window with the result.

For pumping direction towards port, progress is mirror-inverted.In the lower area of the main window you can see a status line in which you cansee the actual status of test progress.

5.4 Print of reportIn the report window you will find the switching surface ”PRINT”. Actuate thisswitching surface in order to have the graphics and the report be printed. Thereport can be shown on the screen again and can be printed at any time (menuFILE-SHOW TEST), but the graphics with the coordinate system onlyimmediately after the test!

5.5 Test StopIf you actuate the switching surface ”STOP” during the test, the test will bestopped after a safety enquiry. The intermediate results obtained so far are notstored in the data bank.However, the test can also be stopped due to a fault condition. If so, you will beinformed by a corresponding notice. Check the cause of the fault and carry out anew test thereafter.



6 Calculation BasicsFor determination of the value GM the displacement of the ship is to bedetermined. Displacement depending on draught and trim is described in thedisplacement table of the shipyard documents. Both parameters can be determinedautomatically by means of the draught measuring device. For this purpose threepressure sensors are applied for determination of the draught and an angle receiverfor inclination.

6.1 DraughtThere are different statements for calculating the draught at draught marks andleads from the draughts at area of sensor installation. The most simple statement isbased on a ship which is not deflected. Then the draughts are calculated acc. to theEuclidean statement concerning rays.If deflection of the ship is considerable, using the Euclidean statement will soonresult in a mistake which can be reduced by a correction.Unfortunately you cannot know in advance how the deflection curve of a ship willrun, because it depends on many factors such as weight distribution of freight andballast, temperature and many others. In this program for calculation of thedraughts the deflection line of the ship was assumed to by a symmetric parabolawith the exponential 1.7, which in practice has shown good results.

For determination of the draughts the in-coming pressures measured by thedraught sensors are converted to the position of the draught marks and the leadsafter correction by the sea water density depending on list, trim and their place ofinstallation.

Since all draughts determined by this method depend on all three draught sensorsand on inclination, the program will not show a correct draught value if one sensorfailed. In such a case the value which is the most close one to the sensor failedmust be entered manually. This is done by double-clicking with the mouse on thevalue to be corrected.Because all draughts depend on each other, all draught values will change when avalue was corrected as mentioned above. Thus if manual input is required becauseof a sensor failure, start correction always at that draught value which deviatesmost from the real value, and after manual input observe change of indication forapprox. 15 s. Now check the draughts not entered manually and effect furthercorrections if required. Concerning the draught values midships it must be takeninto consideration that the values for port and starboard are corrected viainclination of the ship.



6.2 DisplacementAs already mentioned displacement is calculated from the displacement table ofthe shipyard. For this purpose the draughts are converted to a mean draught valuewhich is calculated from the draught midships plus a correction factor of 2/3*sagging. With this draught and trim between the leads the value is interpolatedfrom the displacement table.The value determined by such a way is indicated as displacement after correctionby the Shell Plate factor and the sea water density, and serves as calculation basisfor determination of the GM value.

7 RS485-InterfaceThe data connection with the Hoppe tankmeter and the anti-heeling system is aserial interface of type RS485. The RS232 interface used as a standard at PCs issuitable for this connection only after conversion by an external converter. As astandard the program is prepared for interface COM2.The Hoppe tankmeter as well as the anti-heeling system is connected to RS485.For performance of the test the anti-heeling system must be in STABI-TEST inautomatic mode. The alarm system of the program continuously checks the dataconnection. If alarms are given concerning the data connection, please check thecable connections and power supply for the RS485 interface.

8 Connection of printerAll prints of this program are effected by the standard Windows printer. This isdetermined by means of the Windows print manager. If you want to install a newprinter, please read the corresponding instructions of the Windows documentation.



9 Annex

9.1 Print of example

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