Veleros que aguantan el mal tiempo y los que nunca lo haran

[guillermogefaell]

Mientras esperamos a que contesten los de Ron Holland, creo que es bueno que suba a este hilo la opinión sobre las categorías de diseño de la RCD y la estabilidad, tanto de Andrew Blyth, que es el Convenor del WG22 (el grupo que desarrolla la normativa ISO 12217), como de Barry Deakin de la Wolfson Unit, Universidad de Southampton, gran especialista en temas de estabilidad.

Estos días estoy viendo con ellos y con la DGMM, el problema de algunas lanchas a motor de muy corta eslora de casco y pequeño desplzamiento que se están fabricando y comercializando en España bajo Categoría B, lo que en mi opinión es un auténtico disparate. Parte de lo que me dicen Blyth y Deakin al respecto es interesante traerlo aquí, porque entiendo que es aplicable.

Transcribo algunos parágrafos:

Barry Deakin:


"For such a small craft to operate safely in Design Category B it must be designed to operate in a seastates of 4m significant height, where it will encounter waves much larger than that. Indeed if the operation last a few hours it is likely to encounter waves of 8m! In my opinion it will be in serious danger of capsizing if it operates in such high seastates, particularly if the wavelengths are short or have breaking crests, and the only characteristic that would provide it with good survivability would be an inherent self-righting ability. This of course is not a characteristic easily designed into a small power craft that has any market appeal, and it would be difficult to argue that it is “designed to operate” safely in such high seastates because it will return upright in the likely event of a capsize.

Regardless of the regulations and standards that are in use, designers and builders should have a responsibility to advise their customers of the limitations of their craft. Prediction of capsize is not an exact science so any advice can only be based on an estimate of the safety. Market forces prevail of course, and builders want their craft to be competitive in terms of the labelling as to their use and limitations. The ISO standard set out to provide a level playing field, but the RCD Design Categories are, in my opinion, unreasonable. The categorisation resulting from the RCD is misleading to the public who, in general, have no desire to put to sea in the conditions at the upper end of Category C, far less in Category B conditions as defined in the RCD. Indeed, we have experience of many motor yachts of 40 to 60 metres which avoid operating in seastates above 2m significant height (Category C) because they are intolerably wet, uncomfortable and unpleasant. We should not forget that the RCD specifies that boats are “designed to operate” in these categories, not merely survive them."

(El resaltado es mío)




Andrew Blyth:

"In endeavouring to decide upon stability and buoyancy requirements appropriate to each Design Category, ISO/TC188/WG22 has faced the following difficulties:

1. If Category A is taken as literally unlimited in wave height (according to the RCD) then every boat designed to be operated in more than 4m significant waves must be designed to withstand the very worst that the oceans may generate, waves of perhaps 10 m or more in height. This is then very harsh on boats intended to operate in the lower part of this Category.

...........................
In practical terms, ISO/TC188/WG22 resolved the problem in (1) above by limiting its consideration to waves of 7 m significant height. (Nota: esto significa la posibilidad de encontrase olas hasta de 14 metros) However this has the result that buyers of Category A boats may be misled into thinking that their boat has a truly unlimited capability. The RCD framework provides no means of providing suitable requirements for truly unlimited boats.
...................................
Two possible solutions to this dilemma have been identified:

1. Add two more Design Categories, one above Category A, and one between Categories C and D.
2. Redefine the boundaries of the existing number of Design Categories."

(El resaltado es, de nuevo, mío)

Andrew propone la creación de una Categoría AA, en la línea de lo que creo que ya comenté hace tiempo (Si no fue aquí, fue en Boatdesign.net).

Por tanto, y sin perjuicio de los criterios en los que la velocidad se prima como factor de seguridad (lo que baja el STIX en general) y que tienen su razón de ser, hablando específicamente de cruceros oceánicos para ser tripulados por tripulaciones reducidas, y mientras no se adopte una tal categoría AA, sí que es deseable en general que su STIX sea lo más alto posible, aunque hay casos especiales en los que no es cierto que esto proporcione necesariamente mayor seguridad.

El criterio del STIX ser al menos del orden de la eslora en pies, como regla general y no como verdad absoluta, es una buena guía. Y de ahí para arriba, cuanto más mejor.