The safety of a boat is the sole responsibility of the skipper who must ensure that the boat is fully found, thoroughly seaworthy, and operated by a crew sufficient in number and experience who are physically fit to face bad weather. The decision on whether or not to race, or to continue to race, remains the sole responsibility of the skipper.

Neither the issue of a VPRS rating or rating certificate, nor its use by race organisers, nor any inspection of the boat for rating purposes constitute any representation or warranty as to the seaworthiness of any boat or the safety of any gear and shall not in any way limit the absolute responsibility of the skipper of the boat.

Use of the RCD design category or any other assessment of stability does not guarantee total safety or total freedom of risk from capsize or sinking.
 
OSR race categories

World Sailing publishes guidelines for yacht racing known as the Offshore Special Regulations (OSR). The OSR state that a race organiser should insist on compliance with a minimum stability requirement, chosen to suit the category of the race.

The OSR race categories are:

Category 0: Trans-oceanic races, including races which pass through areas in which air or sea temperatures are likely to be less than 5 degrees Celsius other than temporarily, where yachts must be completely self-sufficient for very extended periods of time, capable of withstanding heavy storms and prepared to meet serious emergencies without the expectation of outside assistance.

Category 1: Races of long distance and well offshore, where yachts must be completely self-sufficient for extended periods of time, capable of withstanding heavy storms and prepared to meet serious emergencies without the expectation of outside assistance.

Category 2: Races of extended duration along or not far removed from shorelines or in large unprotected bays or lakes, where a high degree of self-sufficiency is required of the yachts.

Category 3: Races across open water, most of which is relatively protected or close to shorelines.

Category 4: Short races, close to shore in relatively warm or protected waters normally held in daylight.

The race organiser should publish the OSR race category of each race in the sailing instructions, or in the notice of race.
 

Meeting the minimum stability requirement

For modern production boats built in accordance with the EU Recreational Craft Directive (RCD) it is possible to use the boat's RCD design category (see below) to demonstrate that it meets an appropriate minimum stability index. RCD-compliant boats will have their RCD design category displayed on a builder's (CE) plate attached to the boat; it may also be declared in the documentation supplied with the boat.

For boats that do not have an RCD design category, compliance with OSR stability requirements may be demonstrated using either the Stability Index calculated by the ORC Rating System, by reference to lists of verified STIX data available from IRC or by using a Safety and Stability Screening (SSS) number.

VPRS calaculates an SSS number from measurement data. It is displayed on page 2 of the rating certificate. Note that there may be some differences between the SSS calculated by VPRS and the SSS calculated by IRC.

The OSR states the following minium requirements:

	OSR race category	0	1	2	3	4
	Minimum RCD design category	A	A	A	B	C
	Minimum ORC Stability Index	120	115	110	103	-
	Minimum IRC STIX	32	32	32	23	-
	Minimum SSS number	35	35	28	15	-

 

RCD design categories

A. Ocean: Designed for extended voyages where conditions may exceed wind force 8 (Beaufort scale) and significant wave heights of 4m and above but excluding abnormal conditions, and vessels largely self-sufficient.

B. Offshore: Designed for offshore voyages where conditions up to, and including, wind force 8 and significant wave heights up to, and including, 4m may be experienced.

C. Inshore: Designed for voyages in coastal waters, large bays, estuaries, lakes and rivers where conditions up to, and including, wind force 6 and significant wave heights up to, and including, 2m may be experienced.

D. Sheltered waters: Designed for voyages on sheltered coastal waters, small bays, small lakes, rivers and canals when conditions up to, and including, wind force 4 and significant wave heights up to, and including, 0.3m may be experienced, with occasional waves of 0.5m maximum height, for example from passing vessels.