Racing boats and yachtsman are going to go out on open waters. Various races have committees setting rules to limit the risks. Most of these rules came about after the 1979 Fastnet Race.
Here is what one group (after 5 years of investigation) developed.
CRUISING CLUB OF AMERICA
In the spring of 1980, the Cruising Club of America (CCA), which was preparing to run its biennial Newport-Bermuda Race took a long hard look at the Fastnet race and began to study what could be done to prevent such a disaster from reoccurring.
Five years later, a final report was issued and offers several broad conclusions that help illuminate what is safe and what is not in hull and yacht design.
The conclusions of the report, in brief, are:
- Larger boats are less prone to capsize than smaller boats.
- A dismasted sailboat is more likely to capsize than a boat carrying her full rig.
- A boat has an inherent stability range, ie., an angle of heel past which it will capsize. That stability range can be calculated from the boat’s lines and specifications.
- Some boats designed to the IOR rule, or any designed to be particularly beamy, may remain inverted following a capsize. Boats with a stability range under 120 degrees may remain inverted for as long as two minutes.
- Boats lying sideways to a sea, particularly light, beamy vessels, are more likely to capsize than boats that are held bow to the sea or stern to the sea. It follows, then, that boats that are sailed actively in gale conditions and breaking seas are more likely to avoid capsize than those left to lie untended, beam to the seas.
- The issue of whether or not a boat will capsize, and when and how it might suffer such a fate, is a key point for any sailor contemplating safe extended coastal or offshore cruising. By analysing a boat’s stability range, you can get a very good reading on how the boat will handle a gale at sea and how best to plan your own gale tactics.
The CCA committee that compiled the five-year Fastnet report came up with a simple formula to determine the stability of any yacht of a fairly standard type and of a size suitable for offshore sailing. The formula is as follows:
Capsize Screening # = Boat’s Max. Beam (feet) / Cube Root (Gross Displacement / 64)
In English: take the boat’s gross displacement in pounds, divide it by 64 and then take the cube root of the quotient. Now, divide the boat’s maximum beam in feet by the cube root figure. The resulting number should be 2 or less. In general, if the number is over 2, the boat fails the screen. If the number is under 2, the boat passes. Again, the formula is a very general guide, and does not take into account a number of other important design factors that might lessen — or increase — a boat’s tendency to capsize. Use the formula to get a quick idea of a boat’s stability, but also explore the boat’s full capsize characteristics before you decide to purchase it and set off sailing in open waters.
