After the Work Breakdown Structure (WBS) of a newbuild project has been developed, the next critical step is to estimate the required workforce and clarify resource constraints.
Accurate estimation of man-hours and effective resource planning have a direct impact on project cost, schedule performance, and overall productivity.
In shipbuilding, different organizations use various approaches to estimate the required workforce. These methods can generally be categorized into three main approaches:
1. Historical Data (Organizational Database)
This method relies on man-hour data collected from previous projects within the organization. When a shipyard systematically records and archives the actual man-hours spent on activities, this historical data becomes a valuable reference for future projects.
Advantages:
- Provides realistic and project-specific values.
- Offers high reliability when data quality is good.
- Reduces estimation uncertainty significantly.
- Enables benchmarking between similar projects or vessel types.
Limitations:
- Requires a well-established data collection and archiving system.
- Data accuracy depends on how consistently it was recorded in past projects.
- May have limited applicability for new vessel designs or new production methods.
Even if detailed activity-level data is not available, many shipyards maintain benchmark data at the discipline or workstation level (such as welding, fitting, piping, or electrical work), which still provides useful guidance.
2. Expert Judgment
When historical data is limited or unavailable (for example, with new vessel types or unfamiliar construction methods), shipyards rely on expert judgment.
In this approach, experienced personnel — including workshop supervisors, planning engineers, technical managers, and subcontractors — estimate the required man-hours for each activity or work package. Input from subcontractors is particularly valuable because they often have direct, hands-on experience with similar work.
Advantages:
- Fast and practical when reliable data is missing.
- Incorporates real shop-floor knowledge and experience.
- Useful for estimating new or non-repetitive work.
Limitations:
- Subjective and can be influenced by personal bias.
- Accuracy heavily depends on the experience level of the people involved.
- Risk of over-optimism or underestimation.
To improve reliability, many shipyards use structured techniques such as multiple review rounds or the Delphi method when applying expert judgment.
3. Work Measurement (Direct Measurement)
This method involves directly measuring or closely monitoring the time and effort required to complete specific activities. It is particularly useful when introducing new processes, new equipment, or when no reliable historical data exists.
Common techniques include:
- Time studies conducted on the shop floor
- Work sampling
- Pilot production (demo blocks or sections)
- Continuous monitoring of actual man-hour consumption during the early stages of the project and applying the results to remaining activities
Advantages:
- Provides actual, real-time data.
- Very effective for validating estimates or creating benchmarks for new work.
- Improves accuracy for repetitive tasks.
Limitations:
- Time-consuming and requires trained personnel.
- Results can be affected by temporary factors (learning curve, supervision, motivation, etc.).
Recommended Approach: Hybrid Method
In practice, most professional shipyards do not rely on only one method. Instead, they use a hybrid approach that combines the strengths of all three methods:
MethodWhen to UseReliabilityEffort LevelRole in EstimationHistorical DataSimilar past projects availableHighLowPrimary / Base estimateExpert JudgmentNew designs or limited historical dataMediumMediumAdjustment & validationWork MeasurementNew processes or high uncertaintyHighHighValidation & refinement
Best Practice Recommendation:
- Use historical data as the foundation of the estimate whenever possible.
- Apply expert judgment to adjust for new conditions, risks, or differences in vessel type.
- Use work measurement (especially in the early phase of the project) to validate and refine the estimates.
- Continuously feed actual man-hour data back into the organizational database to improve future estimates.
Key Considerations in Shipbuilding
Workforce estimation in shipbuilding is more complex than in many other industries due to several factors:
- High number of parallel and interdependent activities
- Significant impact of learning curves (especially in the first few blocks)
- Influence of workshop congestion and material availability
- Varying levels of pre-outfitting between blocks
- Use of multiple subcontractors with different productivity levels
Because of these factors, workforce estimation should be treated as a living process. Estimates should be reviewed and updated regularly as actual data becomes available during project execution.
Conclusion
Accurate workforce estimation is one of the most important elements of project planning in shipbuilding. While historical data offers the highest reliability, expert judgment and direct work measurement play essential supporting roles, particularly when dealing with new designs or processes.
The most effective shipyards combine these three methods in a structured and continuous manner. They maintain good data discipline, actively involve experienced personnel in the estimation process, and validate their assumptions through measurement during the early stages of the project. This balanced approach significantly improves the accuracy of man-hour estimates and contributes to better schedule reliability and cost control throughout the newbuild project.
