The Art and Science of Sails

This is an outstanding book! If you want a great explanation of why old theories of aerodynamics are false, and a better explanation of circulation theory, you'll get it here. This book is not for the beginner or the faint of heart; you'll want to pay attention and read several of the chapters a few times. After the book explains a little history, it dives into the theory behind sails. Then sail design considerations and then finally sail trim are discussed. Others here have pointed out that the book is a commercial for North. Well, there is one chapter dedicated to that. You could make a good argument that, since the authors are North people, they are writing about what they know. Most of the book by far is applicable to all sails, even though they do discuss 3Di attimes. I learned a lot from this book an I'll be a better sail trimmer for reading it. Also, it has beautiful pictures.

Son in law recovering from surgery said book was helpful and instructional! Had very high rating and is excellent!

This book answered so many lingering questions that I had about the finer aerodynamic details behind sails. It’s totally worth the price and covers the science in a more clear and direct way than other common sailing books.

The scholarly depth and range makes it a wonderfully interesting read. As a racer (Farr 30, C&C 115) and cruiser (Jeanneau 42DS) I find the lessons tangible and easily implemented. This book exceeded my expectations.

Very technical.

Future sail configurations.

This book is worth reading because the insights from an industry leader, including pictures and graphics from proprietary processes, and the explanations of what sail constructions work best for which application are very interesting. I was struck with guilt in thinking back on a few after-regatta sail loft parties and stumbling against a rack, knocking a half finished sail on the floor, and grinding chicken wing bones and beer into the weave before wiping and reshelving it. To the millionaire who got two fewer crisp tacks than he should have from his Farr 40 headsail, that was me and I'm sorry.There are three problems with this book. First it suffers from the self promotion problems which have been described plenty well by other reviewers. The tradeoff is the book is beautifully made and illustrated, far richer than you'd expect for the price. Second it is not perfectly edited, so sometimes it says windward when it means leeward, sometimes the caption contradicts the text, etc. It's not surprising when a sailor is confident or sloppy, but a professional writer helped on this and should have made it better.The third problem is the big one, which is that all the techniques and reasoning in this book are based on an aerodynamic theory - circulation - which the book treats as proven but which is not. I suggest that theory is incorrect and, if you don't trust it, fully half the book becomes suspect. Someone needs to present a sailor's retort to the swirling tyranny of circulation and here is as good a place as any, even if I'm not the spokesperson the case deserves. (there are solid technical papers debunking circulation if that's what you seek). I am a racing sailor who has made his own sails, who has read enough about sail flow over the ages to know theories come and go, and who has education including at the hands of North Sails, the firm behind this book. I'm not an expert in aerodynamics, but neither are the experts in aerodynamics. That's why after 100 years of flight and millenia of sailing, someone just figured out jetliner winglets a decade ago, even though jibs have been slammed down to the foredeck to clean up airflow at the foil edge since before the real Private Ryan got saved. Circulation is the gospel of a man named Arvel Gentry who did pioneering work with sails and was right about some things, both about flow and about the larger-than-imagined effect of the mast. This is why, for a short period, he was consulted by top sailing teams. The authors have decided Gentry was right about everything, including circulation, but he was not. This is why he wasn't consulted by top sailing teams for longer. Gentry is smart and cranky, and people find it difficult and unpleasant to argue with him. That doesn't make him always right.The case for circulation is circumstantial, in that it goes along the lines of 'how else would you explain XYZ' rather than 'here's proof of circulation' in much the same way people assert it would have been hard for Shakespeare to write all those plays, but they don't have a note from the real author. Here are their arguments and what's wrong with each.The authors state that boats go faster than the wind - thus a magical force like circulation must be at play. This would make sense if boats went faster than the wind dead downwind but they don't, they only do it at an angle. At an angle, the sail is a tool for gathering energy and if the boat is small and sleek it can go faster than the windspeed, just as if the sun were shining at 100 lumens and you had a lot of solar panels hooked to a small bulb you could power it sufficiently to make it shine at more than 100 lumens. Gather energy, concentrate it, use it. Not too hard.The authors state that boats sail toward the wind, which must be due either to circulation or a miracle. Again, if they sailed directly toward the wind this would make sense, but again they sail at an angle. There is a possibility other than circulation or miracles - and it's hanging under your boat gathering barnacles. If circulation made a boat go upwind by its action on the sails, you wouldn't need a keel but anyone who's forgot to drop the centerboard on their 420 after rounding the leeward mark knows you do. If you take a child's yellow triangular block and put one leg against the binding of the complete works of Shakespeare (laying flat on a table) and push a finger toward the binding, perpendicular to it, so it meets the hypoteneuse of the block, the block will slide along the binding even though the force (finger) is going right at the binding. This is upwind sailing. The block is the sail, the book is the keel, your finger is the wind. The block is like so many unhappy high school students and finds the first folio impenetrable but has to yield to the force somehow, so it slides sideways. If you keep angling your finger closer to parallel to the hypoteneuse of the block, this will keep working until you get pretty close to parallel. That's luffing into the wind, that's the edge of the 'no go' zone into which one cannot sail upwind.The authors state that vortices start (the air twirls) when high pressure air drops off the back of the sail (agreed) and the little virtual air wheel those twirls form spins an enourmous opposite-rotating air wheel which envelops the entire sail in a pattern of 'circulation' which travels toward the bow on the windward side, around the front of the sail, toward the stern on the leeward side, and back around the leech of the sail to the windward side again where it just keeps circling the sail this way. A monkey would understand how crazy this is, look out the window of an airplane while you're flying, do you think air is traveling from the BACK of the plane toward the FRONT of the plane on the under side of the wing? How in the world would it overcome 500mph of headwind and even if it did, wouldn't it just create a horrific mess of turbulence? The idea of circulation on a sailboat would mean that air is coming from the back of the boat and crossing all the air which is entering and filling the sail from windward, somehow without either flow (toward the sail or 90 degrees against that flow) being stopped by the other. That's mad.The authors state that circulation is the key which led sailmakers to realize, contrary to popular thinking, that fractional rigs and 100% jibs (small headsails in other words) are actually more effective than big ones. Well, no. Small headsails are effective because of three things - first large headsails put too much power and heeling force in front of the mast for optimal boat design, second the point of a headsail is to organize and blow wind over the back of the mainsail so that it stays attached better and doesn't allow damaging turbulence and drag, and that's only helpful down where the mainsail is really long, and third because it often pays to ease one's main and if the jib is right there a few inches from it you close the slot and make a honking mess when you try to let the main out. The jib is not some upper section of a magical peanut shaped circulation machine, it's effective because a) it's not preceded by a mast and b) it turns the main into something akin to a 'blown flap' on an aircraft, in other words a lift creating device which is resistant to stall. It doesn't have to be big to do these jobs. Small jibs weren't discovered by North post-Arvel Gentry, just look at a Snipe, Star, or Etchells. Gargantuan headsails were pushed by the sailing industry and boat designers until everyone had one (yours truly knows this as well as anyone as a J/24 bowman, suffering a genoa raking over his face for so long on every tack it was almost a relief when the clew finally assaulted his ankles). Then like any good fashion industry they found it was time to make them passe and sell everyone something 'new' which could actually be seen in any sepia'd old photo of a Herreshoff - a jib.To arguments such as this, Gentry says the reason circulation makes no sense is that aerodynamics are not intuitive. i.e. you're just not sophisticated enough to get it. Could be, we have to be open to that, but it sounds a lot to me like the modern artist who says if you think her spray painted dog sh*t isn't art you're just not sophisticated enough to get it. I might not be, but it might also be what it looks (and smells) like.Now you might be thinking, well if they're using these theories to design sails and boats, and they're getting good results, mustn't they be on to something? Well no, because even the most ardent supporters of circulation say things like 'circulation theory is an incomplete theory in that it cannot be used to predict effects without the application of a designed variable assuming circulation'. This is why the text features no 'smoke tunnel' or other actual tests of sails showing circulation - there aren't any. They show some computer simulations they made on the assumption of circulation which seem to indicate circulation because they were written to do so. If I write down that there is a God, I can later 'find' my note and cite it as proof of God's existence. That's as heartwarming to me as circulation must be to Arvel Gentry but far short of a miracle.Gentry is a clever guy and North has some good sails, it's not as if none of the effects they cite exist, they're just misinterpreting them. Air slows on the windward side as it meets the sail, we all agree on that. It's quick on the leeward side because we have to make it that way to get it to stay attached. High pressure exists around the mast because the mast is an obstacle, and some of the air which meets that high pressure goes around the mast to the leeward side. If you take those things together - slower speed on windward, fast on leeward, air going from windward to leeward around the front - you can almost picture this sort of oval of flow, three things going on in the vicinity of a sail which Arvel Gentry misinterpreted as one greater event, an event which would make him the discoverer of that event. But it's like they said in the movie, sometimes i sing and dance around my house in my underwear, it doesn't make me Madonna.

I'm thoroughly enjoying reading this book. The authors make what could have been a technical book a most interesting read. I've learned a lot about materials, design and construction of sails. Makes me appreciate what went into the great sails I've bought from North Sails.

Wer hier erwartet das Buch zu bekommen wird wahrscheinlich, genau wie ich enttäuscht sein. Zugesendet wurde mir lediglich ein Faltblatt.

Pro: Very interesting technical details on various aspects of sailing, modern and up to date theories, makes a cool coffee table book for sailors., fast shipping.Cons: Not a learn to sail book as it assumes some level of knowledge re sailing; expensive

Mucho para leer y entender sobre el funcionamiento de las velas en un barco de regatas. Hay que tener un profundo conocimiento de ingles.

Its a good book to understand the history of sails and technology of constructing sails.I would love to also have a chapter of "solid" wing sails and some in dept how to better tri and make decisions (sailing by lee sailing by luff etc.)all in all I recommend it.cheersDavid Fontyn

An interesting and enjoyable read.