Originally Posted by bobperry
I have said all along the application of chines has to be matched to the specific boat and it's intended target performance. That seems like simple naval architecture to me.
In which case, there is no disagreement between you and Paulo at all, if your position can be summed up in the paragraph above.
I don't believe anyone in this thread has argued that chines are a go-fast / track-like-a-slot-car design feature that can be applied to any boat and magically transform it into a race winner and/or superior cruising platform. If they did, and I missed it, please point me to the claim(s).
I confess that I don't have the luxury of parsing every word of every post like it was Holy Scripture, but I draw impressions from the aggregate of the exchanges on topics like this one, in which I claim no expertise whatsoever, other than having raced at a fairly high level on boats of every type for over 40 years, and reading as much as I can.
Ultimately, nobody is challenging your credentials as a successful, highly regarded NA, whose opinions on such things as chines deserve to be taken seriously. But I have to agree with Paulo that there has been more heat than light in many of the exchanges in this thread, and for the life of me I don't understand why that is.
Clearly there are solid hydrodynamic and engineering reasons to use chines for particular applications on contemporary racing and cruising boats. Many equally successful NAs do so; other equally successful NAs don't, for similar applications. What we're seeking to understand is what specific factors in the design brief influence the decision to employ them or not.
With respect to Open class race boats, like the IMOCA 60s and Classe 40's, we grasp the value of chines given the primary use to which these boats are put: extended, solo / DH offshore racing, primarily downwind. And we understand why some of the virtues that chines bring in that specific application may also hold for peformance cruisers which also spend a good portion of their lives sailing shorthanded in extended offshore / downwind scenarios (or are intended to; like SUVs, plenty of them barely make it out of the marina for a Friday evening cocktail cruise
Perhaps a question I might address to you is the following: If François Gabart showed up in your office tomorrow, a bag of Euros in his hand, and asked you to design an IMOCA 60 for him, would you build it with chines or not? If so, why? If not, why not?
Similarly, if Beneteau commissioned you to design a replacement for the new Oceanis 38, with the design brief of being a stable and comfortable platform for fast offshore cruising by couples, chines or no chines?
I promise to read every word very, very carefully.