Hi Luc,

I raised the idea of the lee hull pivoting for a Bucket List sized craft.  What must be remembered though is that heavier cruising craft are associated with extremely high loads at the crossbeam lee hull join.   Assuming a righting moment of 20 tonne metres, and a pivot arm length of 1 m, the load at each pivot mechanism will be 10 t.  I would only implement this system with hydraulics.  Considering the cable or rope size and winch arrangement required for this application, I don't really see any alternative.  In addition, allowing for dynamic loads due to wind and wave action, the cable mechanism would have to not simply lower than mast to windward or leeward, but also prevent the mast from swinging back toward vertical at a rate which could damage the craft.  Remember that you are considering attempting this in survival conditions.

Many years ago I used to design machinery, much of which involved engineering hydraulic systems.  It is no trivial task to implement these hydraulics either. Excuse the imperial measurements, this is from 15 years or so ago and am still not sure that the hydraulics industries changed much in this regard. As a guide, the 10 t load would require 2 hydraulic rams of 2 1/2 inch bore, 1 m stroke, at a little over 2000 PSI.  However I consider that the shafts of these rams would be vulnerable to buckling, so a shorter stroke, larger diameter ram would be required.  Applying 20 t hydraulic loads at each crossbeam is not for the fainthearted.  I considered this concept (drew some CAD models) some years ago as a means of developing a self righting mechanism for multihulls (undoubtedly, the folding Farrier trimarans provided some inspiration), but haven't done anything since.  I haven't ruled out looking at it again, as my design could still be adapted I believe.