disp/2240/(.01*lwl)^3   Probably the most used and best understood boat evaluation factor. Low numbers (resulting from light weight and long waterlines ) are associated with high performance and quick response. Cruising designs begin around 200 and can go up to the high 300's. Many racing boats are below 100. My approach is to start with a minimum of 230, optimal of 280 - 320, and maximum of 370. This will give us boats with a nice blend of weight (for good load carrying capability and seaworthiness) and reasonable performance. My numbers may seem high to some, but they are in agreement with the experience of many blue water sailors.