| Rob:
|     The suggestion that a complex shape such as the two panels of the hull side, and the bottom on the KD 860 could be infused flat and folded at the seams is patently absurd.
<snip>
| Quite obviously neither of these hull forms could simply be infused and folded as was suggested in a previous post. 

Not Rob, but:
You misunderstood. Rob did not suggest that. It was stated that one can build a cheap, light, strong, go fast, cruising hull out of flat panels, as the link showed. Rob also stated more commonly box molds are used for his designs, as linked.

Of course some designs will require heavier slower, sticker, dusty, more expensive techniques.

| The only time this can be done is when the finished seam angle will be a straight line.

Why can it not also be a simple curve?

|    I must admit that I'm completely unfamiliar with modern MDF. To me it is particle board, which is stiff and inflexible, and is often used as floor underlayment in cheap construction because of it's rigidity.

While this is googleable, mdf is more like paper than particle.

| Also on my agenda is to investigate the cost and availability of Highload 100 and Formular XPS 1000

Ah, there is the titular topic again! Rob, did you ever get your hands on these foams?

|    I'm not sure if a catamaran is a symmetrical proa, or a proa is an
|assymetric catamaran  ;-)

A cat is a boat with the axis of symmetry the wrong way.
A proa is one with a correct axis. ☜(ﾟヮﾟ☜)

| My 30' criteria is pretty well locked in stone.

Ok, fine. But is it fair for me to ask why you have locked it in stone? You seem a reasonable fellow generally. So, I imagine, you probably have reasons for casting this number in stone.

As I review this thread, you have suggested concerns of single handing a larger boat. I do not see any other reasons. Do you have any others?

| It may not ride as nicely as a 40 footer, but will probably ride at least as well as a 40' double ender such as a proa. 

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

|  It's well established that the distribution of the displacement, combined with the optimal rocker, and a transom stern damp out most of the hobbyhorsing.

As I understand it, the key factors to reduced hobbyhorsing is longer hull, bows that do not accelerate upwards as they bury, fine sterns that don't lift as they are lifted on a wave, no rocker, and mass closer to the center of mass. AFAIK shuttleworth said rocker caused it and finer sterns/bows reduced it. All of this makes it seem to me that the hp hulls are optimal. It gets complicated as we discuss corkscrewing effects, but these seem to favour the hp as I see it.