Stability and Safety Screening Numeral

ISAF Special Regulations (see Race Program section of RORC website)

Stability and Safety Screening Numeral

The Safety and Stability Screening Numeral system (SSSN) has now been in use for some 14 years. A value, specific to that particular boat, is printed on each boat's IRC and/or IRM certificate issued by the RORC Rating Office. The higher the value, the more 'seaworthy' a boat is perceived to be by the system.

Organising Authorities may incorporate a minimum qualifying SSSN value for entry to a race. Responsibility for selection of this minimum lies with each Organising Authority. It is not possible for the RORC Rating Office, nor any other body remote from the organisation of a race to lay down recommendations or guidance. Only the organisers of a race can be fully aware of the circumstances of a particular race.

The SSSN is the sum of BASE VALUE and ADJUSTMENT VALUE. These two values are arrived at as follows:

The BASE VALUE for the hull, rig and appendages is computed automatically from the yacht's dimensions and rated parameters. It is the product of several factors, each representing a different safety related feature. A Base Size factor, calculated from the boat's principal dimensions, is modified by each of the other specific factors to take account of variations from the norm. The modifying factors are: displacement/length, beam/displacement, sail area/displacement, beam/length, self righting, rig, keel, engine, and dayboat.

The ADJUSTMENT VALUE (Table 1) allows for recognition of safety related features, principally compliance with a Category of ORC Special and Safety Regulations, not already evaluated by the rated parameters. Its application is optional and a zero value will be applied unless a request by the owner is made supported by a complete check list or an application form (below). There is no charge at initial application for rating or annual revalidation, otherwise the amended certificate fee applies.

Table 1

Full compliance with may be rewarded by Adjustment Value

(unless restricted as shown by Table 2)

ORC Cat 4	+3
ORC Cat 3	+5
ORC Cat 2	+6
ORC Cat 1	+7
ORC Cat 0	+8

Owners may only apply for adjustment based on one of the above ORC Categories if the boat complies all the time when racing IRC/IRM. Alternatively, if the boat does not comply fully with any of the ORC Categories, adjustment for compliance with the specific features described on the application form below may be claimed. The maximum adjustment in this case is +3.

A maximum limit determined by the calculated base value is imposed on the extent of adjustment, as shown by Table 2.

Table 2

Base Value range	Maximum Adjustment Value
less than 8	zero (no adjustment allowed)
8 - 14 + 3	+3
15 - 23 + 5	+5
24 - 32 + 6	+6
33 - 41 + 7	+7
more than 41 + 8	+8

Application of SSSN By Organising Authorities

As stated above, no recommendations or guidance as to the operation of SSSN in practice is offered. Responsibility for selection of the appropriate SSSN minimum for boats in a particular race lies with the Organising Authority for that race. As an example only, the RORC typically uses the values shown in Table 3. There are however circumstances when the RORC will use different SSSN minima for a variety of reasons.

Table 3

Min SSSN	Typical RORC course/ISAF Race Category
10	Typical Solent race/Cat 4
20	RORC cross Channel races/Cat 3
34	Fastnet Race/Cat 2
43	Plymouth to Gibraltar/Cat 1