The "S" Number

[Pat Ross]

In the February/March 2011 issue of Professional Boatbuilder magazine, the ROVINGS section by Dan Spurr, there was a summary of a section of The Design Ratios by Eric w. Sponberg of SPONBERG Yacht Design Inc. dealing with the S Number. The S Number is a formula that assesses relative performance of sailing yachts, giving values that range from 1 to 10.


The Multihull Dynamics, Inc. website has used the term Base SpeedTM to do comparisons of performance potential. It results in a projected Best Days Run speed over a 24 hour period under racing conditions.


The article roused Cal Markwood’s curiosity, Engineering Analyst for Multihull Dynamics, Inc. He was interested in the applicability of the S# to catamaran sailboats and how it compared with Base SpeedTM as a method of evaluating performance potential.

The S Number Multihull Dynamics, Inc. - News Article

Pat Ross

[Pat Ross]

Article update and link repaired.

Multihull Dynamics, Inc. - News Article

Pat