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<< Click to Display Table of Contents >> Navigation: 12. Training Excercises > 12.2 Basic Weight Estimation |
These exercises use the existing training setup and examples in Chapter 11.13, Parametric Estimation. No additional historical database is required.
Practise selecting references, estimating weight and centre of gravity, comparing estimation methods, and checking how subgroup estimates affect the overall result. Use this module after Chapter 11.13 or as additional practice during instructor-led training.
Use the training system and historical database supplied for Chapter 11.13. Its example selects ProjectDB, project type Offshore Vessel / Anchor Handling Tug, and historical database sdb_Demo. Use your assigned login and a unique Project ID, such as EST_PRACTICE followed by your initials. Do not overwrite an existing Tutorial project.
Enter the main parameters shown in Step 3 of Chapter 11.13, or use an instructor-supplied copy with those values. The values are shown in a screenshot in that chapter; they are not replaced with invented values here. Check the displayed units, coordinate origin and positive directions. VCG corresponds to Z, LCG to X, and TCG to Y.
Record the group, estimated quantity, method, coefficient selection, parameter values, active filters, included references and saved result for each estimate. Results depend on the installed demo dataset and settings. Compare results only when these inputs match; numerical results are not prescribed here.
Follow Steps 2–5 of Chapter 11.13. Create your own project and enter the same main parameters. In View > Options, open the Database tab and select sdb_Demo as the historical database. Open Estimate > Reference Projects and use Include all, as in the standard tutorial.
Inspect the available reference projects. Open the estimation for LW – Lightship and identify how the graph and project list relate to one another. Note any active filters or project-type restrictions.
Check: The project uses the intended training database and main parameters. The demo references are included. You can identify a plotted observation and its corresponding project. Selecting a database alone does not activate its references.
Follow Steps 6–10. Select LW – Lightship, open the Estimation window and select Regression for the weight estimate. Update if required and save. Estimate and save VCG (Z), then LCG (X). Return to the main window and record the three saved results.
Lock the Lightship result using the lock/key control described in Step 10 before estimating its subgroups. Record the locked Lightship weight as your baseline.
Check: Weight, VCG (Z) and LCG (X) have each been calculated and saved. You can distinguish the three estimated quantities. The Lightship baseline is locked before Exercise 3.
Follow Steps 11–18. Estimate Equipment weight, VCG (Z) and LCG (X) using Regression and save each result. Move to Hull using the same-level navigation control.
Inspect the default Hull weight method, which uses the Watson E-parameter. As in the tutorial, assume the additional information needed for that method is unavailable. Select Method > Main Parameter, estimate Hull weight using Regression, and save. Estimate and save Hull VCG (Z) and LCG (X).
Check: Record the Equipment and Hull results and the selected Hull method. Explain why Main Parameter can be used with the supplied main parameters. Do not invent missing Watson E inputs merely to obtain an estimate. Different methods are alternatives for the same quantity; do not add their estimates together.
Follow Steps 19–23. Move to Machinery and inspect its unfiltered reference set. Open the range link beside Main engine power and set minimum 8000 and maximum 15000, using the parameter units displayed in the training system. Check the box beside the range link to activate the filter.
Inspect which references remain. With the same method, parameter values and active filter, calculate and record a Regression weight estimate as a comparison. Then select Average, update using the calculator control if needed, and save the Average weight estimate, matching Chapter 11.13. Estimate and save Machinery VCG (Z) and LCG (X) with Average.
Check: The range is both defined and enabled. Record the two weight estimates and explain any difference without assuming one is always preferable. If they agree, record that as well. The result carried forward uses Average. Do not change the reference data.
Follow Steps 24–28. Return to the main window and compare the locked Lightship baseline with the sum of Equipment, Hull and Machinery. Inspect the Remainder group.
In this training project only, unlock the overall result and clear the Remainder weight value as described in Step 25. Check that Lightship now reflects the subgroup sum. Record the difference from the original locked baseline and explain the change.
Produce report 9, Methods and Coefficients, through Project > Reports. For one selected group, open the Estimation window and use Print for the detailed estimation report. Save the completed training project.
Check: While locked, Remainder reconciles the overall estimate and subgroup weights. After unlocking and clearing the training Remainder, the overall weight equals the contributing subgroup sum, allowing for displayed rounding. Review any other contributing groups before comparing totals. Confirm that your report documents the methods and coefficients used.
The existing demo uses ship-related groups and project types in both products. This module practises the shared estimation workflow; it is not the planned platform-topside course. Re-estimation after changing parameters and variant studies can be developed further in Chapter 12.5.
Choose one answer and check it. These practice questions do not record or submit results.