Without a sail a round mast does not produce lift, only drag.  That means at anchor it is not trying to sail the boat.

A soft sail feathered can flap violently in strong wind but has little inertia and a large dead band where it also only produces drag; no lift.  The flapping in strong wind gives eveidence of potential force but the forces are all over the place.

A rigid foil aloft will produce lift at any angle.  There is no dead band with respect to angle of attack and it has inertia.  The inertia combined with the ability to produce lift at any angle means there is a great tendency to synchronise and cause rhythmic rolling and strong tendency to sail when anchored or moored.  

Reducing the area of the rigid foil, as is the case with a wing masts, makes them a little more manageable but still much more difficult to live with than a round mast or near round mast.  For example before Melbourne based Ozone cut his wing masts down he had trouble anchoring.  On one occasion his anchor would not hold and burning fuel to keep position was only short term so he ran on bare masts reaching speed of 26kts to a sheltered creek. 

Wing masts have a wide operating range in terms of AoA and lift coefficient could be up around 2.  The drag coefficient of a round mast is 0.5.  So given the larger lifting area of a wing mast it could generate upwards of 8 times the lift compared with  the drag on round mast of equivalent height.  So the wing mast may only have a fraction of the drag of a round mast but the force it can produce on its own is much greater than a round mast.  Thinking the wing mast will feather to the wind at all times is delusional.

It does not matter how well constrained the mast is on the boat it will still find ways to sail.  Even if perfectly rigid with the deck and boat pointing perfectly into the wind at all time; the slightest roll will generate lift and this can result in rhythmic rolling and/or mast flexing.  The bottom of the mast may not produce lift but the top section is moving across the wind flow so is producing lift.  

A 20m high mast with a chord of 600 could produce a lift force of 12kN in 60kts of wind.  That is a big force to be oscillating 10m above the deck.   Think of a flapping sail in those winds but now every fibre perfectly co-ordinated to work in unison at every angle of attack. 

Things that work well on a fully crewed racing boat that only races in prescribed weather conditions or high speed land sailing vehicle are not necessarily well suited to short handed offshore sailing boat.  At sea the platform might be rolling through 40 degrees, yawing through 20 and pitching through 40 degrees through waves alone.  What force will the wing mast alone generate in those conditions.

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