This thesis is a study of five individual nautical archaeological finds from North Wales. They are the Llyn Peris logboat, Pwll Fanog wreck, Llyn Peris boat, Llyn Padarn boat and the Talsarnau boat. The five vessels are used to assess the inter-reliability of coefficients and ratios of form. The main body of the thesis consists of a record of the five vessels to gain a better understanding of their construction, hull form and a general understanding of the boat building tradition of North Wales. Therefore the production of a descriptive catalogue of hull timbers recovered accompanied by illustrations where applicable forms the core of this thesis. The variations in date and location ofthe vessels gives a maritime in-site into the various historical periods and geographical areas of North Wales. Each vessels is considered in its historical context. The inter-reliability and usability of coefficients ofform generated are accessed against McKee's (1989), descriptive variations of form and the Great Lakes historic ships research project classification of form, termed GHLS (Wilson, 1989: 212). The use of a computer software package, Hull Form 8, to generate the coefficients and ratios ofform is also assessed. The body of the thesis is concluded by a discussion on objectives reached and lessons learnt. It is concluded that McKee's ratio of form are inter-reliable whilst the use of coefficients of form are not. The use ofa computer software package is deemed viable and of use, however certain cautions must be expressed when using such a package. It should be used as an analytical tool and not a design tool. No further enhancement of the archaeological lines drawing should be carried out. A full bibliography and glossary of terms finalises the thesis.