How do sails work by Paul Bogataj

how very interesting
since 13 I have sailed seat of pants, won lots of races, I never knew any of this !!! shud I start over?

 

Just keep watching the tufts and pulling the strings. You can hopefully rely on a good sail/rig designer to worry about the pressure distributions.

Might make a bit of difference if you have a lot of tuning capability in the rig but why rock the boat it you are at the head of the fleet.

Rick W

 

hullo rick , how art thou?
yes, I remember , my P, which all us Kiwis started in, was overweight, the sails were hand me down cotton albeit perfect hand me downs, my dad was never interested, so each summer I would drag the "Shrimp" to the water with a hand made trolley
Sailing dinghys, give a real advantage , later on in the big boats
Sailing is like riding a bike, more so, the FEEL, of the breeze, the eye of the wind I reckon I could sail blindfold,and indeed there are blind sailors, and one eyed sailors too) cheers be happy buddy

 

Good reading thanks guys

i am also a dinghy sailor, and some hobycat
many of todays sailors would be much better if they had the "feel" and cut their teeth on small boats

 

Sail Theory & Practice & Sail Aerodynamics

I always found Paul's explaination to be really good as well.

Here is the man who finally got the discussions on the aerodynamics of sails started down the right path:
Arvel Gentry’s website
http://www.arvelgentry.com/index.html

"If you are interested in sailing aerodynamics and how your sails work, you have come to the right place. All of his sailing technical papers and magazine articles are archived on the Technical Papers and Magazine Articles pages."

Original versions of all of Arvel Gentry’s “SAIL Magazine” articles are included below, as well as other articles that appeared in Yachting, Sea and Pacific Motor Boat, and in Sailing World.
http://www.arvelgentry.com/magaz.htm

Including:

“How Sails Really Work” - by Arvel Gentry
The airflow diagrams in sailing books are wrong!
http://www.arvelgentry.com/magaz/How_Sails_Really_Work.pdf

And other SAIL Magazine Articles:
How_Sails_Really_Work, April 1973
Boundary Layer Flow and the Headsail, May 1973
How a Sail Gives Lift, June 1973
Another Look at Slot Effect, July 1973
More on the Slot Effect, August 1973
Why the Safe Leeward Works, September 1973
The Double Head Rig, October 1973
Checking Trim on the Wind, November 1973
Achieving Proper Balance, December 1973
Sailing to Windward, January 1974
Are You at Optimum Trim?, March 1974

And from Sailing World Magazine:
What Goes Around Comes Around, April 1991
Fluid Dynamics -- How Modern Science and Sailing Discovered Each Other, May 1995

And from Yachting Magazine:
Designer's Forum, Design of the Courageous Mast, February 1975
Sea and Pacific Motor Boat Magazine
Rigging and Handling the Spinnaker, April 1970
Downwind Tacking, February 1970

Sailing Technical Papers:
http://www.arvelgentry.com/techs.htm
Including
The Aerodynamics of Sail Interaction (383KB)
A Review of Modern Sail Theory (453KB)
The Application of Computational Fluid Dynamics to Sails (568KB)
Studies of Mast Section Aerodynamics (248KB)
Sailboat Performance Testing Techniques

___________________________________________
And finally there are lots of good discussions here on this forum:
Sail Aerodynamics
http://boatdesign.net/forums/showthread.php?t=457

 

The interpretation of the dynamics may differ but the illustrated form of an air foil's leading edge seems fairly constant, the drooping D section. Has this form been used in sailing? maybe in a single tack speed sailer? I have posted a tackable design but hesitate building it with no precedent. Is this another example of sailing trailing aircraft design or is this small nuance irrelevant in sailing's chaotic conditions.

 

Yeah - hundreds of times - from the Little Americas Cup solid wind sails, to special double skinned sail systems, to a dozen wingsail variations.

This is nothing new. I suppose the practicalities and costs prevent it from more common usage. After all , the difference between say 12 knots and say 20 knots is still only a bit faster than a fast walk - doesnt justify a sail system 3 times the cost of the hull.

But it doesnt hurt to daydream - and stretch the old greay matter a bit

 

12 to 20 knots? That's worth stretching some material for.

 

Well, perhaps ...

It usually boils down to spending $12,000 on a 75 hp motor to go even faster than 20 knots anytime you like, or $30,000 for a rig that might get to twenty knots if there is some wind.

I still shudder when I hear the prices people pay for say, carbon fibre masts and new sails - (that may be prone to destruction in severe weather). More advanced designs are even more expensive - to build and maintain.

I think you have to be pretty dedicated (and rich) to go out and develop really good aerofoils for boats.

 

Dedication and wealth would help. Maintenance is not an issue with prototypes. Even humble efforts in sailing experiments should be encouraged and given any technical advise they may merit.

 

Oh yes - maintenance is always an issue with prototypes, thats why proven designs are so popular. Prototypes by their very nature are high maintenance. Just read the story of any of the A class cats. Nothing but maintenance and expense.

Personally, the cost and time of exotic rigs and suchlike is largely just a great way for people with too much money to spread it around a bit. If you want to do research, cure aids or the common cold or something - my heroes in the boat world are the Phil Bolgers and James Wharrams, doing more with a lot less.

But, thats just an old mans point of view - have fun your own way

 

New Link for Arvel Gentry's articles

All of those links above for Arvel Gentry's articles are now obsolete (such a shame that history like this gets 'hi-jacked' with some unrelated subject matter)

Here is a good site to access those articles for now:
http://arvelgentry.jimdo.com/articles/

 

Brians reference,http://arvelgentry.jimdo.com/articles/ has some very good content. The first of the series of A. Gentry articles includes copies of letters that constituted a pissing contest between Peter Barrett and Gentry. The technical parts of the articles are interesting and perhaps useful, the follow up letters by the protagonists were lots more fun.