<<The problem with the HP is that it is tantalizingly close to perfection, but doesn't do anything perfectly.  Every 'improvement' comes with a trade off>>

  Agreed.  Nearly every attempt to make it "better" results in the loss of something important.


<<Stayed masts give more power... >>

  Maybe.  For the sake of discussion, though, I'll take the alternate point of view.

  The stayed mast will translate more of a gust into forward motion, but also more of it into heeling moment.  If you've got a full complement of crew who are expert at what they do, and can play the sheets continuously, the stayed mast might have more power.  Or not (because it will be heavier due to compression loads, and require a heavier hull to deal with those loads, plus the drag...).

  However, the unstayed mast might give you a higher average speed because of its ability to dump some of the sudden load from gusts.  That will let you carry more sail area, more safely, more of the time.  A faster average.

  This is just about power, of course -- there are obviously many other benefits of an unstayed mast.

  Most of us are so accustomed to discussing optimization in terms of each element, where all those elements are often given (such as a stayed mast), that we don't look at what the average speed of the full system is going to be.

  It's like the traffic models that assume each car has perfect knowledge of the complete traffic grid as it approaches each intersection, and will then make the logical choice.

  A lot of the arguments for sailing optimization seem to assume a full crew of expert sail handlers and winch grinders who never get tired, never have lapses in concentration, don't get seasick, and don't take breaks to eat, drink, or pee.  Those guys, whoever they are, might be able to take perfection and beat the very good. 

  But for most racing crews, the very good may actually be faster as a complete system when you consider human limitations and adverse course conditions.


<<I am trying to understand it's implications to use it for a cruising HP>>

  Well then, the myriad of other reasons for unstayed masts, side-hung rudders, and so forth, will likely trump the other arguments any way.

  I look forward to seeing the design you eventually settle upon.


<<Rob's real genius isn't the Proa concept, it is his correctly using engineering and material properties that results in lighter, stronger, stiffer, cheaper, better boat and mast designs and applying them to the Proa. In a game of fractional improvements, it is a game changer. It may not sound like much but it is huge. >>

  Definitely.


        - Mike

 

Mike - " You've hit on a chief element of compromise that trips up a lot of folks when looking at the harryproa.  

  What's better:  a) The most-efficient design?   Or,  b) A slightly less-efficient design that avoids likely failures or massive slowdowns inherent in the more efficient design?"

I think they call that a wickedly difficult problem : )

Perfection is the enemy of good enough. The HP is good enough, which is rare praise from me by the way. I don't think I have seen a better design for what it is intended to do, which is nice, fast, efficient sailing.

The problem with the HP is that it is tantalizingly close to perfection, but doesn't do anything perfectly.  Every 'improvement' comes with a trade off, better accommodations makes it heavier, putting the rudders in the hull makes it faster, and more complex, expensive and susceptible to damage. Stayed masts give more power, but cause more drag, stress and weight.  Adding engines and props are tough to do and maybe unnecessary.

It does everything well, especially use the wind efficiently, but there are other boats that do one or two individual things better than an HP. Race boats are faster, cruising boats have more accommodations, Mega yachts empty wallets faster, etc.

Rob's real genius isn't the Proa concept, it is his correctly using engineering and material properties that results in lighter, stronger, stiffer, cheaper, better boat and mast designs and applying them to the Proa. In a game of fractional improvements, it is a game changer. It may not sound like much but it is huge.  

The proa can be optimized for any particular design and the tradeoffs are understood. The template is there, it is up to us to apply it. I am trying to understand it's implications to use it for a cruising HP to keep my wife happy.