Talk:Genoa (sail)

message: A genoa (pronounced like the city, or as jenny) is a type of large jib-sail used on bermuda rigged craft, commonly the single-masted sloop and twin-masted yawl, less frequently on a ketch. Its large surface area increases the speed of the craft; however in high wind conditions a smaller storm jib is usually substituted.
The term genoa is often used somewhat interchangeably with jib, but technically there is a clear delineation. A jib is only as large as the foretriangle, which is the triangular area formed by the mast, deck or bowsprit, and forestay. A genoa is larger, with the leech going past the mast and overlapping the mainsail. Genoas are categorized by the percentage of overlap. This is calculated by looking at the distance along a perpendicular line from the luff of the genoa to the clew, called the LP (for "luff perpendicular"). A 150% genoa would have an LP 50% larger than the foretriangle length. Sail racing classes often specify a limit to genoa size. On International Offshore Rule boats, different classes of genoa have 150%, 130%, and 98% overlap, and so on. Under Performance Handicap Racing Fleet rules most boats are allowed 155% genoas without a penalty.
Genoas do add more sail area to a craft, but at the expense of more difficult handling. It is harder to tack a genoa than a jib, since the overlapping area can become tangled with the mast unless carefully tended during the tack. Genoas are very popular in some racing classes, since they count only the foretriangle area when calculating foresail size; a genoa allows a significant increase in actual sail area within the calculated sail area. In boats where sail restrictions are not applicable, genoas of 200% overlap can be found, although those over 150% are not often seen, since the additional area is shadowed by the mainsail and generates diminishing returns in terms of power per actual sail area.
The gennaker is a fairly new type of sail, and is a hybrid between a genoa and an asymmetrical spinnaker. Gennakers are even larger than genoas (200% overlaps are not uncommon). They have a much greater camber than a genoa, for generating larger amounts of lift when broad reaching and running, but the large camber results in poor performance when close hauled, making the gennaker a downwind only sail. Spinnakers, on the other hand, are strictly for running, and will collapse if used to reach.
Comment:
The phrase in the article above introducing the luff perpendicular is not clear to me.
"This is calculated by looking at the distance along a perpendicular line from the luff of the genoa to the clew, called the LP (for "luff perpendicular")."
A line is a distance between two points.  The clew is a point, but the luff is a line.  One must define the point on the luff to use.
The word "perpendicular" describes a relation of 90°.  A line cannot be described as a perpendicular in isolation.  A perpendicular line is necessarily in relation (90°) to something else which has at least two dimensions (a line or a plane).  Only once the relation has been described can one refer to the perpendicular alone.
If the editor of this article understands the LP, he can easily make the necessary clarifications.  If not, I would be happy to research this point and do it myself. I can't do it right now because I'm in Paris and my yachting books are in Saint-Tropez.
I happened to read the article because I was hoping to learn the history of the genoa.  I'm a specialist of racing sailboats of the class called the 6 metre International Rule.  In our oral tradition, the genoa was invented by one of our illustrious owners of the 1920's, the Swedish diplomat Sven Salèn.  He was apparently posted to Genoa when he developed it.
I was looking for information on the genoese contribution to this invention.  The Web site of the Seawanhaka Corinthian Yacht Club of Oyster Bay, Long Island U.S.A. says that the first genoa was introduced to the U.S. during the 6 metre Scandinavian Gold Cup competition of 1927.  It says that it was introduced by "an Italian boat".  During this competition, Sven Salèn represented Sweden on May Be and there was also an Italian entry named Mati (now Fissa).
If anyone was in a position to introduce the genoa to the U.S. in 1927, it would have been Sven Salèn on his Swedish boat.  Perhaps, Mati had also adopted the genoa.  Perhaps the Seawanhaka confused Salèn's consular posting at Genoa with his Swedish boat - or perhaps they automatically ascribed this genoese novelty to the genoese boat Mati.
I'll ask them if they can sort it out.
Basil Carmody
basil@carmody.ws
Paris & Saint-Tropez, France
: I have added a History section, with a brief summary of Manferd Curry's development of the "Genoa jib". Photos from his book or other sources of "the Swedish boat" and his dinghies (in particular the one of Aero) would be nice if anyone has time to add them. GilesW 12:46, 10 August 2007 (UTC)
thread_title: Comments

message: As mentioned in the History paragraph, the inventor of this sail referred to it as the "overlapping jib". It came to be known as the "Genoa jib" as explained. It is now usually referred to as the "jenny".
I suggest changing the title from "Genoa (sail)" to "Genoa jib (jenny)" or something like that.
GilesW 11:37, 10 August 2007 (UTC)
thread_title:  Proposed title change 

message: I cannot find the term "venturi effect" in Curry's book. I only used it because there was no WP entry for "slot effect". Naughty me! I will correct it.
Curry did claim accelerated airflow behind the overlapping jib, when used with a fully battened main. He also showed correctly that the airflow close behind a main with a jib is faster than the (stalled) airflow behind the same main at the same AoA with no jib. 
Curry was adamant about their advantages over soft mainsails because they allow a narrower slot and a more efficient slot effect. He likened soft mainsails to umbrellas without ribs. I cannot find anything in Marchaj AHOS 2nd ed about fully battened mains. It is fascinating to study Curry's results in the light of modern knowledge, he was surprisingly close to the truth, and spotted something that Marchaj seems to have missed & I had to learn the hard way: when looking for power, mainsails are operated on the ragged edge of the stall. However Currys boats were evidently so much better than the opposition that he sometimes drew the wrong conclusions. He did not mention two-boat tuning.
I think this is the subject of another article. GilesW 17:27, 21 August 2007 (UTC)
thread_title:  Venturi effect 

message: I suggest replacing specific angles with qualitative descriptions, e.g.
"Flat cut gennakers can generally be used closer to the wind than spinnakers. However when running before the wind, the main sail blocks the wind of gennaker, whereas the conventional spinnaker's movable pole allows it to be kept full."
Or something like that. GilesW 11:15, 30 August 2007 (UTC)
thread_title:  Gennakers 

message: I would like to see a citation on the assertion that a jib is defined by being smaller than or no larger than the foretriangle. I have never encountered this usage.  —Preceding unsigned comment added by Millerpd (talk • contribs) 17:58, 21 April 2009 (UTC)
replies: text: From http://www.sailjazz.com/editorial/read/155; "Essentially the key difference is that genoas will overlap the mast while jibs do not. Jibs are designed to fit into the foretriangle, the space between the headstay and the mast. Genoas are designed to overlap the mast by anywhere from a few inches to several feet. Genoas are identified by the percentage of overlap. A 110% genoa overlaps the mast by 10%, a 125% by 25% and so on."  The common use of % overlap in genoa descriptions, as it points out, implicitly supports this definition as well.  scot (talk) 21:04, 21 April 2009 (UTC)
thread_title:  Jib smaller than foretriangle? 

message: The claim of the swedish well known yachtman Sven Salen to be the inventor of the "genoa jib" or overlapping jib, is grossly false.
The genoa jib was first made by the famous italian yachtman Raimondo Panario, a native from Voltri (close to Genoa city) who exhibited it the first time in the winter italian races of January 1926 of the "Coppa del Tirreno" on the 6mR "Cora IV". Of course this new sail allowed him to win these races, and the following ones on the French Riviera (spring 1926)and the Cup of the Denmark's king (june 1926).
Sven Salen never participated in the italian races of early 1926.  —Preceding unsigned comment added by 88.179.141.76 (talk) 13:50, 29 January 2011 (UTC)
thread_title:  Genoa Jib 

message: This link is broken as of 26 Sept 2013.
It appears that the article is available at the following link, but I do not know how to make this change, or if it is appropriate.
http://ljjensen.net/Maritimt/A%20Review%20of%20Modern%20Sail%20Theory.pdf
Can someone help?
Thank you.
Rick  — Preceding unsigned comment added by 198.189.141.254 (talk) 01:57, 27 September 2013 (UTC)
thread_title:  Broken link to article :  A Review of Modern Sail Theory