Sail efficiency = speed gained ?

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Really?

 

I think the referral is to more cubic inches of displacement in a car's engine for performance and more square inches of sail area for a boat. How do they correspond?

 

Modern sailors have had much better boat and sail materials which enable them to push the envelope on stability and strength, but the ideas behind the boats are pretty much the same, just very much more efficient and long lasting now. What's new? Catamarans? Tall light rigs? Hiking arrangements? About the only real modern development that has radically improved performance is the ability to hang ballast very low and cant it to windward when beating. Pretty much everything else is just small linear development of detail and efficiency. Thoughts?

 

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I think your original comment was an unfortunate generalization that ignores all kinds of innovation by modern sailboat designers.
Like altitude controlled bi-foiler configurations for monohulls and multihulls. Altitude controlled three foil systems for multihulls. Various altitude control systems for hydrofoils including Dr. Bradfields "wand" and Greg Kettermans solid state "feelers". The John Ilett monohull variation on the Bradfield "wand". Hydroptere with effective retractable surface piercing foils with a wide speed range. Hydroptere.ch with variable geometry hulls that convert to stepped planing hulls when advantageous. Two foil, single strut hydrofoil systems for kites and windsurfers. Self-tending solid wing sails.
Curved lifting foils for multihulls and monohulls. Rudder t-foils for multihulls and monohulls.The Bieker rudder t-foil. Solid, slotted wing sails. Inflatable airfoil kites that float.
CBTF-particularly the facility for collective "steering". Andy Dovalls winged canting keel-eliminates requirement for extra lateral resistance.
Guy Whitehouse/Jo Richards 110 degree canting keel. Ian Oately's 90 degree canting keel system. Hugh Welbourn's DSS(laterally deployable foil).
And more, much more....
Generalizations like this are never true and serve no good purpose, in my opinion. Ignoring recent* innovation in celebration of historical innovation is unfortunate-both should be recognized and celebrated.

*last 40 years or so

 

Yes, that's what I was refering to as well. It can demonstrated that the dimensional factor which mostly influences the engine power output is not the volumic displacement but the total piston area.
So it is actually square inches (or centimeters) for both cars and sailboats.
Cheers!

 

Generalizations do serve many good purposes. Although they do not technically encompass all possible results, they do allow people to analyze data, develop equations to explain the data, and from those equations enable the ability to predict future results. I'm surprised you are denying this, as you are quite fond of posting predicted performance as solid evidence before actually building and testing something.

Each individual "innovation" has to be measured against historical developments over sufficient time to determine it's place in the pantheon of progress. What seems groundbreaking and innovative today may fade in the passage of time - or may prove to be more important than people today give it credit. I hesitate to label anything as "innovative" or groundbreaking - just as I do not like to dismiss ideas just because they haven't worked yet. Quick to judge is also quick to be wrong.

Generalizations are not popular with the politically correct, with people on opposite sides of issues or people who like to argue for argument's sake. But they are the basis for much science, much development of mathematics to explain results and many things outside technical issues like keeping people safe and secure.

Time is the best jury on innovation, not initial enthusiasm.

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CutOnce

 

Has everyone given up trying to answering my question ?

How does sail efficiency translate into improved performance ?

 

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In fact, I wasn't denying anything nor was I referring to the concept of "generalizations", ah...in general. I referred specifically to one generalization that, in my opinion, presents a very incomplete and inaccurate picture of the actual facts.

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Surely all of those smart guys at North Sails, Quantum etc. have tested and simulated, and know the improvement a 3DL sail has over a conventional sail !

Or maybe they don't - and just ask top dollar for a nice a performance look ????

Someone out there must know......?

 

Now I understand, and I guess that modern engines with large bore short stroke high revs do prove your point. Thank you.
The now outdated quote came from Harley Davidson when they were trying to compete with Honda in the late 60s possibly.

 

Just to challenge this forums participants:

If I had been an America's Cup sail developer at say Quantum or North Sails (they do excist you know) and I had asked for this forum's advise on translating a 5% efficiency gain on a main sail and try to turn this into a speed gain, would you have answered as a) arrogant b) not at all or c) helpful but no facts as my question has had the ill faith of being ?

Uuups - now my rating is probably down one more point on reputation. Doesn't really matter when this forum can add no value.

Thanks

 

Hprasmus, you have been given n answer in the posts #16, #17 and #25.
If you expect to see some reassuring numbers, then you'll get old while waiting. That's the essence of the answers you've been given - the advantage cannot be quantified because it will depend on all the rest of the sailboat (which is not made up of just sails). Performance prediction of a sailboat is one of the most challenging fields in CFD, far from being entirely developed and understood. Not even with all the money in the budget of A-Cup teams.
Cheers

 

Can you define efficiency? 5% increase in mainsail L/D ratio, or 5% increase in drive for the same heeling moment, or something else? What kind of boat, what kind of rig? Once all that is known, it's easy to look at a VPP and quantify the gain in knots, if that's ajat you want.

 

Thanks daiquiri,

Your answer suggests that not even the most advanced sailmakers have any idea of the performace gain of their various sails ? Very interesting. So all the hype of sails designed and manufactures to suit cruising, racing and AC are just unsubstatiated marketing gimmicks ?

Is there not a sailmaker out there that could add wisdom to this hypothesis.

Thanks.

 

Of course it does, it's basic math, but only if the boat keeps the sail the same size as what is being "improved", not making it smaller, which puts you back where you were in your performance/speed/VMG to windward, but costing more money due to added complexity.
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Rant alert, click away now.
If we improve something, it's supposed to work better, not just cheat a rule for those who can afford it. But I guess in some eyes, that's improvement.
As with all sailing things that truly fly and compete with each other, BMW Oracle etc and all the techy, foil-ey, wing-ey, solid-foil-sail, always-delicate high speed, usually multi-million dollar interesting boats that are thrilling to watch, but need a support boat with a machinist to keep all in order once a week at least, and has been pointed out above, fads and experiments come and go, and they are just logical steps forward in well-known widely published fluid-flow technologies, like airplanes. The Wright Flyer of 1903 uses the same aero tech the F-35 or SU-27 does.
All are as cutting edge and experimental in pushing the limits as the budget allows in the desire to get to windward first, then get down wind first, and this drive so one can be first and get all the attention is very simian and the usual thing, and once necessary in war (Baltimore Clippers 1812 for example) to impose our viewpoint on others and avoid having theirs imposed on us, but this does not mean these racing gadgets will exist 20 years from now, because they have no economic support other than rich folks experimental toys that are used 8 weeks a year at $100,000 a week to really race, and spend the rest of the time hauled out in Monaco, or break under too-hard use, or inevitably are left behind by the next tiny step in performance efficiency and wind up in a scrap heap like their long line of predecessors. You don't go cruising in one unless you have deep deep pockets and an EPIRB because they break at inconvenient times.
A good new idea is something that lasts.
Earliest cast in stone documentation of spritsail in recognizable modern form on a large trader is on a Roman sarcophagus of the third century AD. This held on in Thames barges making money under sail until the 1960s (documented 1,700 years of continuous, profitable, commercial, not toy use) so was a good new idea and still a great small boat rig.
Since needs these days are no longer carrying manure or bricks, but to experiment in very high efficiency and pushing as hard as possible at the laws of thermodynamics in the quest of pure knowledge and social competition, we see some very cool boats and startling things. But few will be around one thousand seven hundred years from now like the sprit rig probably will in some form, because they do not have a reason to exist other than "gee whiz", and for a lucky few to win money through advertising support as they compete with each other and entertain us on TV, like Gladiators in Rome, only here the stakes are money more than lives.
Announcer: "Well, folks it's pretty gusty today, and they're at the mark and GOOSE is on her foils at 42 knots under the 6 spreader 140 foot tall carbon rig but GANDER is hot behind and extending the controversial inflatable battened headsail, and Wow look at her go! 44, 46 knots but GOOSE is at the mark first and getting her spinnaker ready, and here comes the mark and around they go and GANDER has deflated the battens and unrolled the rest of the sail, and Oh No GOOSE wrapped her spinnaker and she's broaching there she, Oh the rig came down!... Well, there goes 15 million dollars. Ha ha ha, now for our commercial.".
Audience says "What's on Jersey Shore?" as they wonder where their next meal or health insurance payment's coming from.
End rant.