Defect Analysis to Improve Quality in Traditional Shipbuilding Processes

). Defect Analysis to Improve Quality in


Introduction
The sea is one of the livelihoods of the Indonesian people because of its many benefits, such as fish, marine plant cultivation, and others. Most Indonesian people in the coastal area work as fishermen whose existence and role are very important in development, especially in the fisheries sector. Indonesia's abundant marine resources. Ideally, the fishing community can also get a quality of life following its strategic role. Along with the coast of Aceh with its waters, of course, it has great potential in the field of fisheries. Along the coast in this area, many residents work in the fisheries sector, including in West Aceh Regency, which has such a wide coastline that many residents work as fishermen.
In general, fishermen in West Aceh District still use traditional ships made of wood, so traditional ship makers experience much demand for ship production. In addition to many requests, craftsmen also experience problems during the manufacturing process, so the ship's quality is sometimes different from the standards or wishes of the ship owner. This condition is a consideration of fishermen because many complained about the condition of their boats, which are quickly damaged. A good ship will impact the safety and comfort of the crew while working, especially during fishing operations.
For solving this problem, initial identification processes were conducted to determine any potential defects that may affect the quality of the ships. In this work, defects that pose a high risk to the quality of the ship were resolved using Logic Tree Analysis (LTA) to obtain recommendations for improvements. The Failure Mode and Effects Analysis (FMEA) approach will be incorporated to identify the potential damage, effects, and impacts on the ship. FMEA is widely used in various engineering fields, particularly in assessing the production systems of manufacturing activities (I Pamungkas & Dirhamsyah, 2019;Rastayesh et al., 2019;Yucesan et al., 2021). LTA has been widely used in various problems, such as minimizing the risk of natural disasters (Bommer & Scherbaum, 2008;Porter et al., 2017;Satake et al., 2007), machine maintenance problem management (Tang et al., 2015;Waghen & Ouali, 2019, 2021, and operational hazard risk (Abdelgawad & Fayek, 2012;Akyuz et al., 2020;Ramzali et al., 2015). In addition, the integration of the FMEA and LTA approaches is part of the Reliability Centered Maintenance (RCM) approach (Alencar & de Almeida, 2015;Gupta et al., 2016;Tang et al., 2017). The results from this work will be able to identify and solve defect problems, hence improving the quality of traditional shipbuilding using the LTA approach.

Materials and Methods
This research was conducted at a traditional shipyard in Tanjong Village, Meureubo District, West Aceh Regency, Indonesia. Figure 1 shows a map of the research location. Researchers start the initial stage to identify the research object after searching the topic. Initial identification aims to determine the object of research in general, such as the shipyard's condition and the problems these ship crafters experienced. Figure 2 shows a research flow diagram.
International Journal of Global Optimization and Its Application Vol. 1, No. 3, September 2022, pp.135-144. 137  The stages of data processing carried out in this study as seen in Figure 2: • Determine the cause of defects in the traditional shipbuilding process.
• Identify failure modes, effects, and solutions to minimize defects, along with the Risk Priorities Number (RPN) using the Failure Mode and Effects Analysis (FMEA) approach. FMEA is a useful approach for evaluating failures or defects that occur in systems, process designs, or services (Iing . Identifying potential failures is done by providing a score or score for each failure mode based on its occurrence, severity, and detection (Stamatis, 2003). In this research, FMEA will identify functions, failure modes, failure effects and preventive measures of each defect's causes in traditional shipbuilding. Identifications were collected from interviews with the owner and shipbuilders. Each rating has potential, and the scale is rated from 1 to 10 (Arabian-Hoseynabadi et al., 2010). After getting a score for each assessment component, the next step is calculating the risk priority number (RPN). Equation 1 follows to calculate RPN (Kim & Zuo, 2018). RPN = Severity x occurrence x Detection • Take measures to prevent defects in traditional shipbuilding using logic tree analysis (LTA) (in tabular form). Logic Tree Analysis (LTA) aims to prioritize each damage mode and perform a function and damage review. The priority of the damage mode can be determined by answering the questions that have been provided in this LTA (Waghen & Ouali, 2019). LTA contains information regarding the number and name of damage, amount and mode of damage, criticality analysis and additional information required. The critical analysis places each mode of damage into one of four categories: evidence, safety, extinction and category (Rabinowitz et al., 1998). In this International Journal of Global Optimization and Its Application Vol. 1, No. 3, September 2022, pp.135-144. 138 study, every defect in shipbuilding will be given the appropriate questions to be further analyzed in the maintenance task.
• Select maintenance tasks for each cause of the defect.

Determining the Cause of Defects
The causes of defects in traditional shipbuilding are determined based on common occurrences observed on the various ships. As for some of the causes of defects in traditional shipbuilding, namely: • The wood quality does not meet the requirements, namely when the wood drying process is not perfect and there are wooden knots that can cause gaps during assembly. Figure 3 shows the poor quality of the wood.

•
The choice of how to use bolts and nails that rust easily is still not quite right. Figure 5 shows bolts or nails that rust easily.
• Install motor drive tubes and rubber pipes where low-quality materials are used. Figure 6 shows the installation of motor drive tubes and rubber pipes.

Failure Mode and Effect Analysis (FMEA) Result
FMEA starts by determining the failure mode and identifies each failure mode's impact and the Risk Priority Number (RPN). The FMEA method is based on discovery, regulation, and failure or error reduction and has been used in various industries (Rhee & Ishii, 2003). FMEA uses three risk factors to identify failure modes, namely occurrence (O), detection (D), and severity (S). The risk factor is indicated in the form of RPN. Three input parameters are rated on a 10-point scale (I Pamungkas et al., 2020;Iing Pamungkas & Irawan, 2020). This paper analyses the four causes of defects in traditional shipbuilding using the FMEA approach. Failure modes, effects and damage prevention are measures to be identified in advance. Tables 1  and 2 show the FMEA and RPN for defects in traditional shipbuilding.  (336), Bolts or nails that rust easily (252), and installation of motor drive tubes and rubber pipes (150). The highest cause of RPN defects is found in poor-quality wood. It reflects that traditional shipbuilding's main ingredients greatly affect the ship's overall quality. This problem can be overcome by choosing the right wood to prevent damage. The next highest RPN is for mismatched connections; it can be fixed by reconnecting. Bolts or nails that rust easily can be prevented by replacing these bolts with hotdipped galvanized bolts. Errors in the installation of motor drive tubes and rubber pipes can be prevented by protecting the pipe rods from opening directly.

Logic Tree Analysis (LTA) and Selection of Maintenance Tasks
LTA is carried out to make maintenance or repair task decisions using the decision logic tree criteria. The criteria used are based on the failure mode, failure detection method, and equipment failure characteristics (Song et al., 2008). Table 3 and Table 4 of the four causes of damage in the traditional shipbuilding process, several measures can be proposed. The poor quality of the wood causes the ship to crack and break easily, making it easy to rot and leak. It is advisable to replace the damaged components with new ones. An improper connection can reduce the ship's strength and make it prone to leaks. It can be recommended to be reconnected if a leak occurs. Rusty bolts or nails can easily cause fractures and cracks, so they leak easily. It is advisable to replace them with hot-dipped galvanized bolts. Incorrect installation of the motor drive tube and rubber pipe can cause it to break easily and leak at the joint. It is advisable to take corrective action on the joint. Here are some descriptions from Table 4. a. E is evident, and H is hidden. b. Risk characteristics, S is severity, CL is the current likelihood, CR is the current risk. c. A selected task, PL has projected likelihood, PR is a priority risk  Table 3 shows the precautions based on LTA, and Table 4 shows the selection of maintenance tasks. Disconnected and leaking The connection broke and leaked E Description: Installation of motor drive tubes and rubber pipes  Disconnected and leaking Repair Table 4 displays four risks of damage that affect the quality of the traditional ships produced, namely, the selection of the quality of raw materials that have an impact on ship cracks and rupture, incorrect connections that can reduce the strength of the ship, bolts or nails that rust easily, which can cause cracks and leaks, and installation of motor drive tubes and rubber pipes that cause the pipes to break easily and leak. Several actions can be used, among others: replacement of damaged components, reconnection, hot dipped galvanized bolt replacement, and repair of the installation of additional equipment. Several inputs can be used to improve the quality of traditional shipbuilding, namely careful and precise planning for the use of the main material (wood) and additional materials (pipes, bolts, nails, etc.), making standard operating procedures (SOPs) in the manual book, conduct training to workers regularly, set standard shipbuilding time per unit, and create a layout for each stage of shipbuilding.

Conclusion
Along with the increasing demand for traditional ships, ship quality is one of the most important things that ship manufacturers must pay attention to meet customer satisfaction. Logic tree analysis is used in this research to solve quality problems or defects in traditional shipbuilding. It is hoped that it can improve the quality of the ships produced with the recommendations for improvement obtained. The causes of defects commonly found in the traditional shipbuilding process at the research location will be identified first. The logic tree analysis (LTA) method was applied to traditional shipbuilding for the research work reported in this paper. On the basis of the results, four risks of damage have been identified that affect the quality of the traditional ships produced, namely, the selection of the quality of raw materials, imperfect wooden joints, easily corroded steel bolts, and poor installation of additional equipment. Several actions can be used, among others: replacement of damaged components, reconnection, hot dipped galvanized bolt replacement, and repair of the installation of additional equipment.