Do you mean to suggest that a proa does not ride well for its size?

That is exactly what I mean to suggest, though lacking any experience to compare the two it is only a gut feeling based on what I know of hull design.  The very nature of a double ender eliminates some of for and aft assymetery that has been developed improve ride.   The length compensates for this at least to some extent, as does the concentration of mass in the center.    This is not meant to be critical of the Harry Proa designs.  The designer has parameters to work within, and the knowledge to produce the best product that fits within those parameters.   I suspect that Rob has done a good job judging by the level of innovation and outside the box thinking he as incorporated into the Harry Proa designs.

Its a good question, field evidence has it that longer hulls pitch less, and here we seem to be talking longer in terms of 33%. But also the bow offset of proa hulls is likely to reduce that further. Besides there are hydrodynamic fixes for pitch and pitch oscillation, just because catamaran builders rarely make the effort to control pitch doesnt mean it cant be done

    To suggest that catamarans builders rarely make the effort to control pitch is absurd.   Pitch control has been the holy grail of good catamaran hull design since the days of Woody Brown.   The hull designs you see today are the product of that effort.   There is no disputing the fact that longer hulls ride better, but the challenge is to achieve the best ride for the length you have to work with.   Boat designs are full of compromises.  For example, I'm willing to accept the flat bottom of the KD 860 hull, which is less efficient than the round bottom of Sagitta, both for simplicity of building, and for greater load carrying, not to mention having the cabin sole closer to the bottom of the boat for a lower profile for the given draft.    The narrow bows, increasing in displacement fairly rapidly, and the transom sterns rather than double ender canoe sterns, are used BECAUSE they offer less pitching.  The placement of the accommodations / widest hull portion is not an accident.  It's designed to concentrate the greatest weights at the optimal axis, which is close to the pitch axis.  
    There is a great deal that has been written on this topic, and I've read it voraciously, and unfortunately have not kept a folder or bibliography of it.   Much can be found on the internet using Google.   Chris White's book, The Cruising Multihull, which is part of my growing library on multihulls discusses this in some depth.

    Unfortunately most commercially built cats are in many ways no optimal.   They are of course built for a specific market, and the buyer's priorities, but that's inevitable.   The priority of the racers is speed, the priority of the charter market is lots of accommodations, and a panoramic stand up bridge deck with every possible amenity imaginable.  My priorities are safety, payload, close windedness, a tolerable motion, and decent speed, as well as low initial and ongoing costs..... I'm sure I've forgotten something.   


                                                                                                                                    H.W.

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Posted by: StoneTool <owly@ttc-cmc.net>

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