Gareth,

>>I didn't misinterpret righting moment and healing moment I deliberatly swapped one for the other. My understanding of these two is that while they have different meanings they are equal and opposite so one can't increase while the other stays the same.

This is a deceiving way of putting it. While your statement is correct is suggests something that is not correct.

By virtue of this relatio you conclude that while the heeling moment is unaltered by move the mast to the windward hull that the righting moment isn't changed either. BUT the maximum ACHIEVABLE righting moment is changes; this is increase to a crew is forced to depowered at a higher windspeed.

So yes there is always equilabrium but the windspeed at which extra effort needs to be taken (depowering the rig) is affected which in turn means that the overall speed of the platform is affected in depower conditions.

In the example the modified boat can sail faster in depower conditions because as a result of the increased MAXIMUM righting moment it needs to depower less to maintain equilibrium. Less depowering means more power in the sail and means faster sailing.

The analogy to trapezing or not trapezing is quite good. Also here the heeling moment is not directly changed but still teh boat with the trapezes is faster in depowering conditions than the one without.

>>Can you explain how RM and HM can be different.

It comes down to the fact that the relation to HM and RM is one of equality. It is more a master-slave relationship with two distinct windspeed ratios.

Light winds to fully powered up. : RM follows HM
Fully powered up to strong winds : HM follows RM

All the best

Wouter