In the 3-4-5 system 3 units are measured on the baseline tape, 4 on the offset tape and when 5 units are measured between the ends of these measurements one has a perfect ninety degrees between them. This method was adopted due to its ease of implementation, need for only simple equipment, low cost and accurate results. Results were filled in by pencil on a pre-formatted table printed on Permatrace drawing film. This material is resistant to the effects of wind, rain and mud and corrections can easily be made in the field with a simple rubber.
All this sounds remarkably civilized, the reality was somewhat different. First of all the results had to be taken quickly as the wreck was completely engulfed at high tide and, at best, one only has two hours to deploy all the equipment, take the results and return to the safely of the shore. All this was further compounded by the thick mud, wellies were useless only drysuits were of any practical use.
Once safely home, rejuvenated with warm drinks and the equipment washed down and stored the results taken were transferred to a computer program (Site Recorder SE) for plotting.
The results gained showed the smooth lines of a racing boat not that of a hard working coaster! This was the first clue that the initial identification of the ship was incorrect.