G. Alblas | TU Delft Repository

Are current shipbuilding cost estimation methods ready for a sustainable future? A literature review of cost estimation methods and challenges

Review (2024) - Gerrit Alblas, Jeroen Pruijn

In the fiercely competitive shipbuilding industry, precise cost estimates must be considered as they serve as a critical input for determining market prices effectively and ensuring a small profit for the shipyard. In Western Europe, where most projects are Engineering-To-Order (ETO), cost estimations are extra challenging, due to lack of similarity between projects. On top of this, cost estimations are becoming increasingly difficult in a market confronted by mounting challenges related to safety regulations, cost-effectiveness, and the pressing need to address energy conservation and environmental protection. New technologies introduce changes in nearly all aspects of shipbuilding design and construction. This article conducts a literature review, to present the state-of-the-art methods for estimating man-hours, explicitly focusing on man-hours for shipyard production, excluding overhead costs and challenges the suitability of existing systems for ETO and especially for the changes caused to ships by the energy transition. An indication is given of the practicality of each method as outlined in the literature. A solution direction, incorporating the construction process, is proposed to improve cost estimations for ETO projects in pre-contract phase. ...

A Novel Concept for Steel Building Cost Estimation in Shipbuilding Using Process and Product Similarities

Journal article (2024) - G. Alblas, J.F.J. Pruyn

Accurate cost estimates are essential for staying in business in a competitive shipbuilding industry. With new technologies and the energy transition creating an ever-changing landscape, traditional cost estimation methods based on product specifications can no longer keep pace. The need for improvement especially arises for Engineering-To-Order projects, considering that the profit margins are narrow. The use of process information in the estimation process could increase the reliability and flexibility of these estimations. This article presents a concept that utilizes graph theory to include process information in the cost estimations applied to steel buildings. This concept is specifically suited for the early stages of Engineering-To-Order projects. ...

An expert system for cost estimation of shipyard steel assembly

Conference paper (2019) - Marije Deul, Bernades J. Hoek, Sietske Moussault, Anna-Louise Nijdam, Gerrit Alblas, Robert Hekkenberg

The current cost estimate applied by shipyards in the pre-contract phase is insufficiently valid and accurate for “one-off” ships. Most shipyards use the unit man-hours/metric ton for the estimation of man-hours in steel assembly. This key figure does not take blocks’ properties and the required actions for assembly into account. It is evident that e.g. welding above head by hand or Submerged Arc Welding (SAW) and the amount of lift and turn movements influence the lead-time and number of man-hours. The estimation of man-hours in steel-assembly can be improved by the identification of production patterns and the resulting actions. Therefore, the rationale, the reasoning and decision-making processes of the production engineers needs to be captured. This paper focuses on rationale capturing, codifying and storing for (re)use. First, it is discussed how the rationale is captured through experts-interviews, based on the reactive knowledge capturing method. Thereafter, it is explained how the captured rationale is stored in an Expert System, linking construction plans to a fitting assembly-order. This resulting assembly-order can be used to derive the amount and type of actions required. This enables a better substantiated cost estimate. The developed system in this research is generally applicable and proves the concept. The paper concludes with recommendations for future research, which includes further automation of this Expert System and integration of man-hour calculations. ...

Similarity-based cost estimations for eto-products

Conference paper (2018) - Gerrit Alblas, Jenny Coenen

Correct and accurate cost estimations are critical for shipyard companies. Traditionally cost estimations for one-off ship designs are based on expert opinions and statistical-based methods. In this paper, we introduce a method for improving cost estimations in the pre-contract stage of a one-off design shipbuilding project. Pre-contract means that the available information is limited. The introduced method is based on the idea that, although a new vessel has never been built before, cost of similar building assemblies can be found in the production information of earlier produced vessels. The assessment of similarities is performed by means of error-tolerant graph matching. Research to date shows that only taking the basic activities into account, without taking the context into account, does not always lead to a good and reliable result. The example in this paper is based on the ship block assembly process. ...