Truly I do not see the interest of building a Spray replica. It's a design more than old (when Slocum rebuilt the Spray, this boat was already a very old boat), it's truly archeology...It's a loss of money and time. It's not even cheap.
I want to stay polite, I'll say nothing about B.Roberts and consorts...
I've seen such progress in Naval Architecture (I don't talk about floating condos for mass market made in frozen cod -ie mat and polyester-) that I do not see any interest to build an old design replica, and to spend one buck on that.
Would you build a Fokker 1917? a 1911 Ford T? no, for sure. Aviation and cars had made some progress. I wouldn't build even a Piper Cub replica, when you can build a Banbi (220kg, 2 places, Rotax 80HP, 305 kmh max speed, 240 kmh (150 mph) cruising speed burning 12 L/h- a bit more than 3 gallons per hour of ordinary gas...that's efficiency-) for the same price, and the same STOL qualities...
Aesthetics? it's rather easy to design a modern yacht with a traditional look interpretation. In cars, look at the Mini Cooper made now, reminds the old Mini Cooper of the 60's (which was a piece of junk, my mom had one...) without the prohibitive defects.
As I do not want to die totally stupid, may someone be kind enough to explain to me the rage of those old yachts designed 40-50-60 and more years ago?
First of all, I don't think its fair to compare a traditional sailing work boat based on at least a thousand years of technology to an automobile or airplane designed from an only eight year old technology. The world's first real airplane was probably the '08 Wright Flier. The '03 version did get off the ground but had bad CG issues and, as replicas have proven, was practically un flyable. A 1911 Model T was based on an even younger technology. The real world problems of automobiles were not likely to be discovered until more ordinary people had cars. It took a long time to design a front end system that was stable at any kind of speed, as old car buffs have told me.
Second. The SPRAY had wonderful course keeping qualities and was not all that slow. She is reputed to have maintained 8 knots in a good wind. That's a lot faster than I can swim. More importantly, it could do that while keeping a course with no one at the helm, without late 20th century equipment such as wind vane, and later autopilot steering. And that included down wind sailing which, even today, is the usual choice for long voyages.
Modern sailboats are lighter displacement and can usually sail well past 'displacement speed'. Heavier traditional boats really can't (surfing down waves doesn't count). Modern boats are more maneuverable because they have separation between keel and rudder. This same maneuverability can make them some what more squirrely going down wind compared to a properly designed long keel boat. Modern boats tend to have deeper keels that resemble airplane wings. They require a travel lift to get them out of the water and a cradle to store them on land, as well as to repaint the bottom.
A long keeled boat can set on its keel as the tide goes out and have first one side then the other scraped and repainted. Try doing that with a more modern design.
Modern multihulls are really based on mid 20th century airplane technology. They are designed to have minimum weight to maximize speed. At least two early trimaran designers were aircraft engineers. Modern multihulls combine light weight with high loads. They are not only capsizeable (as SPRAY was), but they also sometimes come apart. The modern trimaran has full buoyancy floats. As far as I can tell, no Pacific islander trimarans had those, so they are really a mid 20th century invention. Pacific catamarans were made of large trees, hollowed out, and built up with planks. These hulls were joined by heavy beams and had, by today's standards, very small sail plans. Still, under the right conditions, they were capable of sailing quite fast. But slow by today's multihull standards. A modern multihull, like a super model, always has to watch its weight, because rigging loads and hull loads are directly proportionate to weight. On most monohulls, especially more traditional ones, this is often not the case.
Now I am not knocking modern monohull or modern multihull design. These boats have all proven their seaworthiness when properly designed and intelligently handled. But, as with a more traditional design, you have to know what you're getting into and what the trade offs really are.
I think there will be plenty of room on the sea for more traditional designs, such as SPRAY for a long time to come. And that more modern designs, with their strengths and weaknesses, merely add variety of choices.