Southampton, for ISAF meeting on 15 september 1997
50 AND 60' OPEN SECURITY
- Human problems
- The boat
- The solidity
- The stability
- Unsinkability
- Further researches
- Regulation to be improved
The series of 60' and 50' open is a young serie and is interesting because it allows innovations and real progress on boats, especially on building and handling.
Indeed, problems of sails and boat control for a single handle skippering a 18 m are relatively close to these of a father family on a 12 m.
Each race brings experience and it is necessary to pull conclusions to improve boats and regulations in order to make accidents decrease
Objectives are, by order of priority:
1) to return the skipper
2) to return the boat
3) to have a correct classification out the finish line.
The security and the reliability of the boat solve many problems. It is necessary to manage :
· Human organisation problems
· Nautical qualities of the boat, its solidity and its stability.
· The security equipment of the boat, the control of the weather situation where the boat will be going.Human problems
90% of accidents would have been avoided if each actor had well fulfilled its role and is well with the other team members .
| · The skipper | He has to define well its manner of sailing and its program because then he's the one to exploit the boat, in the limit of its own possibilities and of the boat. |
| · The sponsor | He has to follow and insure that the team has the proper financial resources to work. |
| · The architect | He has to conceive a safety boat, strong and stable |
| · The builder | He has to build the boat correctly and respect the prescribed strength. |
| · The assistant | Before and during the race, he has to insure that the whole equipment is in good condition. |
These different actors have to be free between them and to express the ideas they have to tell. They have to be united really. All of them have to have a right of veto on questions of security. In the same idea, it is necessary to not have budgetary arbitration on these problems of security.
Qualities of the boat
· Easy and good control of the boat
· Facility of manoeuvre
· No diving
· Rest for the crew
are elements that are not under regulations and that are due only to the work quality of the architect and to the comprehension of phenomenon.
A great part of accidents of the last Vendée Globe race are due to keels being broken or detached of the boat.
This type of accident is more frequent than the capsizing due to the boats stability. Current resistance norms are 2G to the fatigue and 3,5G to the rupture approximately. May be it is sufficient for current boats, if the boat is well built and if the skipper never fails. Besides, boats of the Open Class undergo important lateral acceleration.
If on top of this, one inadvertence occurs, we think that it is necessary to have at least 3 G in fatigue and 5 G to the rupture.
To face 2 inadvertence, 4G and 8G, 10 to 12G in the laminate.
In previous races, there has been structural problems, hull especially, caused by stem shocks , due to slamming or floating objects.
For this reason, we choose to have stems in monolithic with stringers. It resists better to shocks and especially, allows to see the state of the structure after damage.
In the slamming zone, the water pressure we do recommend are large enough .
· 30 meters of water pressure on the hull skin
· 15 meters of water pressure on the longitudinal stringers
· 6 meters of water pressure on frames
These structural problems find their origin in the design, building and especially in the life of the boat. It is necessary, during the life of the boat, that the architect is always present and shouldered by capable organisms to verify the solidity of the implementation or the evolution of the state of the boat. It is necessary that the owner of the boat has ways to pay the assistance of the architect and especially to make necessary expenses to maintain the boat in good condition.
The boat has to be capable not to overturn under the effort of the wind or under the effect of a breaking wave. If despite that it is capsized, it has to be able to right up (CF GZ to 90°)
1-The GZ at 90, with the horizontal mast, allows to measure this capacity to right up under the effort of the wind. schema GZ
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2-A supplementary stability margin allows to avoid a too easy capsizing_. A theoretical positive stability at 120 can allow to improve this type of problem, but not fully.GZ curve 0°
| GZ Curve according kanting keel angle lateral angle of the keel 0°
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3-If unfortunately the boat has been turned over by a brutal wave, it is necessary to have ways to right up the boat . GZ Curve 45°
| GZ Curve according kanting keel angle lateral angle of the keel 45°
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| Ways to right up are : |
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To well surround the problem, it is necessary to control stability curves with and without the mast and with the different possible positions of fin and the different movable weight.
- Division of the boat in several tight compartments
- Strength of the hull to bulkhead joints
- Door sufficiently large to move from one compartment to the other
- Fix or inflatable volume for unsinkability.
| · hull form - front parts -simulation, tank test |
· Materials - shock resistance - shear resistance Monolithic for hull and ballast Sandwich for the deck |
Regulation to be improved
Everything can not hold in a regulation ; the good conscience of
actors is the essential element.
The communication between skippers , architects ,
builders are the best improvement factor.
Certain rules are however necessary to avoid some
actors give priority to speed rather than safety.
The technique allows to improve boats with time. The
technical improvements are to be focus on the solidity and on the
stability of boats. It means that it is necessary to
accept improvement every 2 or 4 years of regulation in order to improve safety aspects.
We propose now :
· a minimum GZ (mast horizontal at 90°, empty boat to make the measurement easier) : 90 cm
· An GZ in extreme conditions, (water ballast and keel on the bad side) : 55 cm.
· For the new boats, an angle of capsize theoretical (it means the prolongation of the natural curve) to 120°.
It is necessary :
· to publish the stability curve of boats with and without the mast, curve is to be corrected by a measure at 90° .
· to put on site redundant systems to right up a boat capsized by a wave : water ballast, keel, airbag.
These measures on the stability can be settled only if similar measures are taken for
the solidity of keel fixation. Without that , the skippers
are going to increase the weight of bulbs without taking necessary measures for the
fixation of the keel.
The solidity of keels will have to be at least 5 G to the rupture
and 3G to the fatigue with ways of control and
publication on new boats as well as on the old ones.
For hulls and the solidity in general, it would be good that architects and builders publish their structural calculation; the outstanding navigation of such boats would serve the experience for all.
We can thank these sailors who give us example and allow to explore unknown areas, to repel limits and thus to improve the security of navigation in general.