Golden Globe Race 2018.

[caribdis]

En la experimentada visión del navegante y diseñador neocelandés Eric Bretscher http://nordkyndesign.com/category/sailin...-dynamics/
se refiere al tema:


Towing Drogues

Drogues are anything attached to the stern that will cause increased drag at speed. It can range from a long warp, some warp and chain or more sophisticated and purpose-designed devices like a Jordan Series Drogue, a collection of little parachutes attached to a long warp.
Attempting to tow drogues in heavy weather is a double-edged sword:

• By increasing drag and overall resistance, a drogue pulls the yacht further up the slope of the wave as it approaches, into a steeper gradient and closer to the broken water of the crest.
• By introducing an additional resistance force located as far aft as practical, the drogue can mitigate or cancel the shift in hydrodynamic resistance towards the forebody of some hulls. This can greatly help with preventing excessive course instability from developing.

Towing a drogue shifts the average position of the resistance forces closer to the centre of gravity and helps cancelling unstable yaw moments, but at the cost of increasing total resistance and pulling the vessel up the wave slope.

I personally don’t favour the use of drogues in general. I wouldn’t think of deploying anything alike unless there was a clear-cut and observable reason for doing it. I will rather stabilise tracking using aerodynamic means as described further up than slow the hull down in the sea. Different boats exhibiting different properties in following seas may be forced to opt differently.
Towing a suitable drogue can provide considerable benefits for boats that lack the course stability required to run in following seas. How much and how long for is a matter that will still depends on the hull design; drogue or not, the boat will still accelerate in front of a wave steep enough and may still bury the bow.
Once deployed, most drogues aren’t practical to retrieve before conditions subside due to the enormous forces involved. If the strategy doesn’t work out or becomes unsuitable, there are few options but cutting them away.


Una arma de doble filo: aumenta la resistencia al avance y por tanto no deja al barco escapar de la rompiente, y por otro lado evita que las fuerzas hidrodinámicas se muevan demasiado a proa en algunos cascos, lo que podría evitar una excesiva inestabilidad de rumbo..