Analysis of the Dimensional Properties of "Samanala/Dingy" Boats Manufactured in Sri Lanka by Using DNV-GL Standards.

Abstract

This paper is focused to evaluate the dimensional properties of "Samanala/ Dingy" boats manufacturing in Sri Lanka by using Det Norske Veritas (Norway) and Germanischer Lloyd (Germany) standards (DNV-GL). According to the survey conducted by the authors, it was identified that the Sri Lankan boat builders are mainly using Fibre glass Reinforced Plastic (FRP) materials and open mould (hand layup & spray layup) technique for manufacturing boats. Furthermore, the authors recognized that more than 75% of the boats building industries do not have structured design process within their industrial setup and the boat designs are mainly conducted on the task base external consultancies. It was noted that most of the fishing boats are manufactured without using a properly designed frame work and the same mould was being used for a number of years without analysing its performances. The thicknesses of the boat structures are mainly decided by the experience of boat builders and they are using higher safety factors to compensate their rational less design process. Consequently, it results an overestimation of dimensional properties of boat structures which make approximately 16% of materials wastage. There are number of boat building standards are in place around the globe including DNV-GL, American Bureau of Shipping (ABS), Nippon KaijiKyokai (Class NK) and Lloyd's Register etc. By using these standards, the boat design process could be improved and materials wastages could be minimized. In this research, three regions were identified to estimate the material wastage of "Samanala / Dingy"boat by applying DNV-GL standards. The thicknesses calculated from DNV-GL rules and actual thicknesses available in the existing boat structures were compared for the regions above the designed waterline, below the designed water line and bow area near to the keel. Based on the results obtained from the study, conclusion and recommendations have been made for the Sri Lankan boat builders to encourage to use the existing boat building standards applicable to the global contest.