Catamaran

Sailing

LCB and CP

In "Sailing Yacht Design - Practice" (edited by Claughton, Wellicome & Shenoi) Alexander Simonis presents a case study for the design of a cruising cat. He presents a table of the design parameters for 17 of his charter cat designs. The LCB for his designs varied from 53.1% to 56.43%, and the center of flotation varied from 53.53% to 58.42% of the waterline length. In contrast to Shuttleworth, he places the LCF a little behind the LCB. In the paper he discusses the evolution of these parameters, and their relation to the rig center of effort, as his designs evolved over time. He says of his latest design "It is considered that the fine entry combined with the LCF positioned as far back as possible would reduce the pitching motion as long as the LCB moved rapidly foward when the bows went down. This is also partly why the bows have a slight angle forward instead of being plumb as seen on earlier cruising designs." For this design (the Moorings 4500), the LCB is at 55.23%, the LCF at 56.36%, the CE at 55.95%, and the center of lateral resistance (CLR) at 56.03%. Cp for 17 different designs ranged from 0.534 to 0.598.