Hexagon completes IMOCA 180 test in Around Alone stopover port |
| Tuesday, 14 May 2002 |
| The 180 degree test is part of the statutory tests demanded by the open class regulatory body IMOCA, which is affiliated to the international sailing body ISAF. It’s unprecedented in terms of what it requires and this simulated inversion is not required in any other racing class in the world. It is part of a strict series of regulations and physical rules demanded by the skippers themselves (IMOCA is a skipper’s association) whose aim is not only to see the class develop faster and more exciting yachts, but also safer ones too.
The main crux of the safety requirements for the rule pertaining to open 60’s is that at a defined measurement trim they should have a vanishing angle of stability of not less than 127.5 degrees and be self righting (without mast) in flat water. Both of these conditions have to be physically tested and written compliance from the designer and/or builder is insufficient. Other significant safety requirements are that the yacht should be fully watertight, contain 5 watertight bulkheads and in addition to this that the total volume of the structure (plus 50% of any water ballast tank volume) must equate to 130% of the yacht’s measured displacement. Short of complete disintegration of the yacht this makes them virtually unsinkable. Significant rules also apply to the number and siting of liferafts, safety gear and communications equipment , as well as rules similar to those enforced by ORC.
With respect to the 180 degree test, although it is conducted without a mast, in Hexagons case (and of probably most other open 60’s) the yacht only utilises a fraction of its available keel swing in order to right the boat. This is also carried out in flat water without any help from wave slope and so realistically, in the unlikely case of a 180 degree inversion when the mast survives, the boat would similarly self right itself. In fact assuming that the yacht in these conditions would already be sailing with keel canted, this whole event would happen automatically with no requirement for the skipper to do anything other than hang on.
For the test itself, a strop was placed around Hexagon’s keel by a diver and then the yacht was pushed out into open water by the action of the crane ‘jibbing out’ . At this stage the crane began lifting the keel and Hexagon was raised onto it’s side and finally rolled over in a relatively gentle fashion onto her back. During all this time Graham Dalton and his shore manager Brad Kellett were inside. Once at 180 degrees, both men split up and inspected the yacht for and aft for leaks and to make observations on survive-ability issues in this unusual condition which could however remotely occur from loss of a keel after impact or damage. Once back in the main compartment, the keel, which during this time had remained in an almost central position was dumped by pressing ‘float’ switch which allows the keel to move under the action of gravity alone. This action can be carried out manually and simulates the ability to move the keel without the presence of electrical power. The keel slowly moves off the centreline and as the keel angle begins to become greater the yacht begins to heel over. Eventually the angle of the keel is sufficient to bring the deck clear of the water and initiate a complete roll over. This occurs with more than one third of possible keel cant remaining.
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