RCD Design Categories for RIBs


Few topics have created such a stir as how to assign the RCD design category for RIBs.  It is still possible to find RIBs of 5m in category B (offshore) while some 7m RIBs are only category C (inshore).  How can this be?

This discrepancy will ultimately be cleared up by the all-new RCD which comes into force in January 2016 and is mandatory by January 2017. The majority of RIBs shorter than 7m will be forced to drop to category C.  Until then, some examples of smaller RIBs in category B may remain at large.

To understand how this came about, one has to look at the evolution of the RCD and the family of standards particular to inflatable boats (EN ISO 6185 parts 1 to 4).  The RCD became optional in 1996 and mandatory in 1998 but EN ISO 6185 parts 1 to 3 were not harmonised in EU until 2002. Part 4 (for RIBs longer than 8m) was harmonised in 2012.  So this means that when the Directive came into force, there were no standards for inflatables for the industry to use. Thus each manufacturer and certifier made their own judgement about the applicable category.  As one would expect, there was quite a range.  Some manufacturers labelled 2.5m inflatables in category A (ie ocean-going) since there was nothing to say they couldn’t!

When EN ISO 6185 parts 1 to 3 were issued, they omitted any reference to design category.  (It is alleged that the non-EU based delegates of the ‘international’ ISO committee would not allow reference to an European system of categories). So the conflict of RIB categories for RCD was not eradicated.  However, part 3 of the standard (for inflatables up to 8m with power greater than 15kW) did include an equation to calculate a “stability factor”. A score above a certain value allowed a RIB to be called an “inflatable offshore boat”.  Since “offshore” is also the designation for category B, some certifiers adopted this equation for assigning the design category.  This provided an even playing field for the categorisation of RIBs but the problem is that some boats at 5m will achieve offshore status by this equation.  This standard is still in force and this is why one still finds 5m RIBs in category B.

But some time after issue, EN ISO 6185-3 was provided with an ‘Annex ZB’ which stated that RIBs wishing to assign category A or B should not use the stability factor in the standard but should use the stability standard for non-inflatable boats (EN ISO 12217).  The problem with this suggestion is that (a) the Annex ZB is highlighted as ‘informative’ ie that it is not a mandatory part of the standard and (b) the scope of ISO 12217 states that the standard should not be used for inflatable boats.  The scope of a standard is ‘normative’ ie it is mandatory.  So manufacturers and certifiers were faced with a choice of using informative guidance over mandatory elements of standards or rejecting guidance and sticking with the mandatory parts and continue using the ‘offshore’ stability factor of EN ISO 6185. Different certifiers went different ways and the discrepancy in the market place remained.

Then in 2012, part 4 of EN ISO 6185, for RIBs longer than 8m, was published for the first time. This had a completely different approach and required category B RIBs to use only certain part of EN ISO 12217.  This proved to be relatively straight-forward and the industry happily adopted this approach.

At this point it became clear that EN ISO 6185 part 3 (which was up for its statutory review) would also enforce the use of certain parts of EN ISO 12217.  EN ISO 12217 was also up for review and it was equally clear that RIBs were no longer to be excluded. (Both these standards have, very recently, been published with these anticipated changes).   More certifiers, therefore, adopted the EN ISO 12217 approach for all RIBs when part 4 was published.  Some did not and still await the formal harmonisation of the recently published standard.  It was found, however, that no RIBs below 6m could achieve category B using ISO 12217 and only the very heaviest RIBs in the range 6m-7m would make category B. Thus a change of standard enforces a change of category for many RIBs.

HPiVS did adopt the new approach when part 4 was published….but only for new assessments.  A certifier does not have the right to withdraw category B certificates from those using the old approach because the legislation has not changed.  In other words, if a boat was certified as meeting the law, correctly, on day A, then the same boat cannot be found to be non-compliant with the same law on day B.  The law sits above the standards.  When certified, a boat is declared as compliant with the law on the basis of compliance with particular standards but there is no legal obligation for a manufacturer to adopt updates to standards, particularly for previously certified products. (If there was an accident which might have been prevented if the updated standard had been applied, then the manufacturer would have to come up with a good excuse why they had not opted to adopt the update but without an accident, there is no compulsion for a manufacturer to adopt an updated standard).

So unless a manufacturer voluntarily opts to adopt the new standards, they may keep their old certificates… until the law changes.  When the law changes the manufacturers must have new certificates and the certifiers, such as HPiVS, will demand the application of the latest edition of the standards.  The RCD will change in January 2016 and must be adopted by all before 18 January 2017. So this problem will disappear in time.

In the meantime, it would be very wrong indeed for a buyer to assume a category B RIB from manufacturer X is more seaworthy than a category C RIB of similar size from manufacturer Y. It may be quite the reverse. It all depends when the boat was certified and which edition of the standard was used.  As the newer standards offer a more rigorous test, the age of the certificate is a more reliable guide of seaworthiness: the younger the better.

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