This autumn the International School of Yacht Design organized the Principles of Yacht Design course at Forum Marinum in Turku. The course was held during two weekends with lectures from 10 am to 5 pm. So obviously there was a lot of information to be learned in just four days. 

The goal of this course was to give an extensive introduction to the subject and to provide essential background information and terminology needed to read further literature on the subject. So in this respect the course served both the amateur designers and sailors who are just interested to learn more about their boats. 

A modern wing theory was dealt pretty thoroughly in the course, since it plays such a major role when designing the optimal shape for the keel, rudder and the sails. In the history, it was thought that boat should have a long keel in order to prevent the boat from drifting sideways. However, with the advancements in the airplane wing theory, boat designers started to understand that keels (and sails), work like wings and generate lift which prevents side-slipping. According to the classic wing theory, the most efficient shape is a long and narrow keel, which generates more lift and has a lower wetted surface. That is what we are seeing nowadays in modern racing boats.

During the second weekend, the emphasis was on the forces affecting the boat, different construction materials and their strengths and weaknesses. Espeacially interesting was the lesson which dealt with different forces, that affect a sailing boat. For example, on a normal sailing yacht, the pressure on the mast foot can be as much as double the boat’s displacements. Also the loadings from the shrouds can be very large – about the same as the boat’s displacement. Also the keel and the rudder are under heavy loads when sailing in rough seas. So you want to be sure, that the designer has done the math right.

I found the course very interesting, although at times the physics and math were over my capacity. However, maybe one of the most valuable insights during the course was to understand and to learn to appreciate the complexity of designing a sailing boat. Things like the optimal shape of the keel or hull may be modelled in theory, but especially in a cruising boat one has to take into account also practical aspects related to the manufacturing costs, maximum draft, the strength of the keel in case of grounding, ease of handling with a small crew, comfort at sea and on harbour etc. So clearly the boat design and building is always about making compromises. After this course I am even more convinced that boat design should be leaved for those who have enough understanding on the subject. Therefore, the challenge for a sailor is to find a boat whose designer has made the most optimal compromises (for you).
/Antti

The course was organized in Forum Marinum, a maritime museum, which is a perfect place for this kind of course. Here are some photos from the exhibition: