Ok, moderatly long winded but hear me out. I'm gonna bill this as a blend of Bill and Wouters statements.

My favorite comedian is George Carlin. He does a bit about license plates and the things that the states put on them for slogans. One of the states that he mentions has “Live free or die!” on it while another has, “Famous potatoes”. He comments on the absurdity of these two and states that the truth of the world probably lies somewhere in between.

I think this whole discussion is in the same ballpark as George’s bit. The real answerer is some where between Bill’s brute force method and Wouter’s extreme finesse.

The construction techniques available to us today are much more advanced at a more reasonable/reachable price than in the past. Carbon is still exotic, however much more becoming the norm for many components. We can decrease weight, increase strength and produce a mast which will bend anyway we want just by adding a little carbon here, removing some there. Producing not only a lighter stronger mast, but one that is possibly more effective across a wider range.

The laws of fluid dynamics have not changed, but our understanding of them has improved. Not only our understanding, but also our ability to more accurately model the flow of fluids across sails, hulls and other appendages. When I was in ChE class, our professors would have us do more work on a problem than was specified in the book. When we asked why, he replied, “Your books were written in the 50’s, since then computers have come a long way. Since you do all of your work in MathCAD, you can more easily do the complicated calculations that are required.”

Older hull and sail shapes designed by paper, spreadsheet and slide rule would take drastically longer to design than newer ones done with the current crop of software. The older shapes would most likely be less efficient than their new counterparts. By “hand” we can only calculate a certain number of intervals along the hull to judge the effectiveness of the design. While the software packages can do extraordinarily finite calculations across the entire surface to produce a more accurate picture of what is going on with the hull and sails. Some of the software (I think I saw it somewhere) is not only looking at the hull through water, but the hull and sails as a complete package with wind and waves. This provides more information than was ever imaginable before to determine the optimum direction to take the hull design in.

The best designs are the ones that not only provide for a great deal of power, but also incorporate it in the most efficient package possible while staying manageable across a wider range. I think the true art of design is knowing how to find the optimum middle ground…not only power, but efficiency also. Realizing that not only power and efficiency are needed, but look at things like momentum. The HT was on the efficient end of the spectrum, but look how it does in waves….or doesn’t when the wind is light. A down fall of that particular design.

Wouter and Bill are both coming at the same problem in two different directions. Wouter has probably spent more time behind a keyboard while Bill more time at a drafting board. I can’t give an edge to either design method because there is much to be said for both experience and computational ability.

I think I read the statement earlier in this post about formula rules limiting creativity (or something like that). I think it is completely to the contrary. If given a set of design guidelines I would expect it to take much more creativity and ability to produce a winning design. Since the major parameters have been established (LOA, SA, beam, mass) your brute force (SA/mass ratio) has already been determined. To create a more flexible and effective platform within those guides would require more resourcefulness to get the most out of the available power.

Look at two similar designs, the I-20 and the N-6.0.


These numbers straight from the Performance web page
I-20 US 390 lbs 246 ft^2 SA/wt=0.6308
N-6.0 NA 420 lbs 264 ft^2 SA/wt=0.6286

The sail area to weight ratios are VERY similar, however the I-20 beats the 6.0 upwind. (I only mention upwind because with today’s Bermudan rigs, they are mostly optimized for upwind.) Why is that? More efficient platform I suspect (hull shape, square head, aspect ratio of foils and sails). I would also suspect that the I-20 has also had more time put into its sail plan optimizing it for upwind (since it was designed for a spi).

I’m no expert, but I think your both a little crazy/fanatical (did have some psych in college….)! You both believe deeply in your design philosophies. Like I said before, I think that anyone can make a boat faster by adding some sail or by improving it’s efficiency, however if both are not considered together the end result will be less than equal to it’s full potential.


Will R