Originally Posted by monsieur bis
I am amazed how JFD designed such a boat and not being a NA. But he has done so...
.. And while the Boreal and the Allures are similar concepts in certain respects, they are also I think quite different. If I understand correctly the Boreal is more of what we in France call a dériveur lesté (a keel/centerboarder maybe in English), while the allures is more of a dériveur intégral (a centerboarder with internal ballast only). This means that a dériveur lesté has a shallow keel which houses the centerboard thus allowing it to be lower, as well as providing a lower placement of the lead ballast. The argument also goes that this shallow keel improves tracking. As far as I know the allures carries its ballast in its bilges and its centerboard is only heavy enough to insure it doesn't float given it is a NACA foil section and thus has volume. Because of all of this I would be very surprised if the allures had a lower center of gravity, even considering it has a fiberglass deck. In any event, this is how I understood the differences between the two boats.
It seems to me both concepts are similar:
On boreal site they say:
The ballast is housed in the keel box. Compared to a centreboarder, this again lowers the CG by several dozen cms. Unlike normal practice, we don’t pile up lead blocks as ballast. At Boreal we construct moulds of every ballast compartment and we make massive lead blocks to fit each of them, resulting in a gain of 20 % in density.
All this efforts contribute to an impressive stability curve.
and give the idea that the box is outside the hull and that is not the case.
For what I understand both boats are centerboards with all ballast inside since they have no ballasted keels and no box outside the hull, as some centerboarders have.
Regarding the keel, both boats can have profiled nacra centerboards beeing the one from the Allures slightly deeper and the boats have also two rudders so I cannot see how that improves the tracking.
I have the stability curve from the Allures 45. If Hannah2 can provide us with the one from Boreal 44 we can compare them but I don't expect it to be much different.
A good Christmas to you.