Definition of a spinaker
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Category: Dinghy classes
Forum Name: Dinghy development
Forum Discription: The latest moves in the dinghy market
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=866
Printed Date: 14 Aug 25 at 3:37pm
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Topic: Definition of a spinaker
Posted By: Strawberry
Subject: Definition of a spinaker
Date Posted: 19 Jul 05 at 9:19pm
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How would you define a spinaker? Supposing someone put a 21sqm sail on the front of a Cherub which could go be used to beat? ------------- Cherub 2649 "Dangerous Strawberry |
Replies:
Posted By: maxim
Date Posted: 19 Jul 05 at 9:36pm
| that would be a very large genoa would it not... |
Posted By: kasey3000
Date Posted: 19 Jul 05 at 11:04pm
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Spinnakers have an unstable luff.....thats why they collapse on too tight a reach and why they won't fly at all upwind. ......Think about it....main's have the mast to support the luff and the jib/genoa has a wire in the luff to add support. If you stuck a wire in the luff of a kite and put tension in the wire(like you would on the jib/genoa)...it would probably sail upwind! ........i think Although I think this is open to discussion? Kasey |
!!!!!!
Posted By: Ian99
Date Posted: 20 Jul 05 at 12:21am
It doesn't need this to sail upwind  . I remember sailing against a GP14 a few years back who managed to get around an entire race without taking his spinnaker down.He wasn't going particularly slowly either - nearly keeping up with me in a laser! Admittedly he did have a little help from the tide and the "upwind" part of the course was a series of fetches. I was quite impressed how effectively he tacked with the spinnaker up though - very few boats can do this without going backwards!  |
Posted By: Stefan Lloyd
Date Posted: 20 Jul 05 at 6:56am
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RRS 50.4 "The difference between a headsail and a spinnaker is that the mid-girth of a headsail, measured from the mid-points of its luff and leech, does not exceed 50% of the length of its foot, and no other intermediate girth exceeds a percentage similarly proportional to its distance from the head of the sail. A sail tacked down behind the foremost mast is not a headsail."
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Posted By: Phil eltringham
Date Posted: 20 Jul 05 at 10:14am
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I remember trying to sail upwind in a 200 with the kite up, you just ease the halyard about six inches and it works reasonably up to about F2, not sure if its really faster, but it was good fun. ------------- FLAT IS FAST! Shifts Happen |
Posted By: jpbuzz591
Date Posted: 20 Jul 05 at 10:58am
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my knackered spinnaker wont fill if u try to sail it deep and the only way to fill it is to keep heading and we got very close to beating with it. Very strange ------------- Jp Indoe Contender 518 Buzz591 Chew Valley Sailing club Bristol |
Posted By: kasey3000
Date Posted: 20 Jul 05 at 11:19am
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We can sail on v.v.v.tight reaches in the Kestrel with our kite.....but none of our fleet have managed it on a beat We find that on extremely tight reaches or even when it's a fetch and we carry the kite.....it is slower, it feels like we're sailing through treacle! Once we tested it with my 200 and a friends Kestrel on the same leg of the course( a tight reach)....and the symmetric kite of the Kestrel could sail higher than the 200 with the asymmetric... which we found odd because the asymmetric is the same sorta shape as a jib!...so we thought the Kestrel kite would falter....but it didn't We found that older kite's don't like sailing on tight reaches!!!.....the luff would just collapse straight away! Oh well!!! kasey |
Posted By: JimC
Date Posted: 20 Jul 05 at 11:44am
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50.4 doesn't apply to Cherubs: its specifically excluded in the class rules.
Back in the 60s the class widely used little triangular kites with wire luffs (set from poles). You whammed down on the pole and it would carry well above a true beam reach. They were lousy on broader reaches though, and they disappeared as Olympic courses became widespread and you never sailed beam reaches anymore. Now you could create a triangular asymmettric that would carry upwind. It would be a bit undersize probably. You'd probably have to relocate the daggerboard forward of the mast in order to make the boat balance. Then you'd find that the extra speed would bring the apparent wind well back so you'd have to be sailing very low upwind, so wouldn't gain as much as you'd think. Then you'd discover that your performance offwind sucked because the kite only worked well hard on the wind and you're only allowed one kite on board under Cherub rules. Taut luff asymmettric kites were common on 18s and things before the 80s, maybe before 70s. The loose luff modern asymmettric, as conceived by Andrew Buckland and popularised by Julian Bethwaite has pretty much made them existinct. So you can try it, but I doubt it will be a race winner 95% of the time: it would certainly be prettty poor on windward/leewards. Here's a celebrated pic of a wire luff kite on a 60s Cherub. 
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Posted By: Scooby_simon
Date Posted: 20 Jul 05 at 12:31pm
Most of us at the ECPR were using our kites up wind quite well for part of the trip out of the river (Was keeping up with most of the Tornado's too and then it all went wrong !)------------- Wanna learn to Ski - PM me.. |
Posted By: Strawberry
Date Posted: 20 Jul 05 at 6:15pm
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I'll re-phrase my question, if i made a 21sqm jib, what would make it a jib rather than a spinaker? ------------- Cherub 2649 "Dangerous Strawberry |
Posted By: kasey3000
Date Posted: 20 Jul 05 at 6:38pm
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For one the kite is made of a different, much lighter material than the jib.....i don't think a jib would be any good in a kite material?.....too thin??? The shape would be completely different, even comparing a jib/genoa to a asymetric....a jib has a slightly curved foot and a kite has a very curved foot....goes very high at the clew. ........if you want a jib that big.....get a Flying Dutchman!...............plus, it wouldn't comply with the Cherub rules Kasey. ------------- 49er 908 |
Posted By: Strawberry
Date Posted: 20 Jul 05 at 6:57pm
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So is it the material that makes a spinaker a spinaker? If you made a jib out of spinaker material would it be a spinaker? ------------- Cherub 2649 "Dangerous Strawberry |
Posted By: kasey3000
Date Posted: 20 Jul 05 at 9:36pm
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NO!!! although....spinnaker material is defined as "spinnaker cloth". Just checked in the English Dictionary.... "Spinnaker = a large triangular sail carried opposite the mainsail of a racing yacht running before the wind." "Jib = a triangular staysail extending from the outer end of the jib-boom to the top of the foremast or from the bowsprit to the masthead." Just keep the jib for upwind and the kite for downwind!!!! Kasey
------------- 49er 908 |
Posted By: I luv Wight
Date Posted: 20 Jul 05 at 9:51pm
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We have been here before.... a few years ago.
It would be possible ( under cherub rules) to use a 'spinnaker' that is very flat , used upwind like a huge jib, and to have a very very big mainsail. However this would ( probably) only be any good in force 1 or less upwind, and no good in anything downwind. So it's an expensive way of (perhaps) more speed upwind in conditions when racing is cancelled. |
Posted By: Stefan Lloyd
Date Posted: 21 Jul 05 at 7:06am
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I've just looked at Cherub class rules at http://www.sailingsource.com/cherub/chframe.php - http://www.sailingsource.com/cherub/chframe.php and wow, they are short. Since, as has been pointed out, RRS 50.4 is excluded, there does not appear to be any definition of what is the jib and what is the spinnaker. You can't have a 21 sq m "jib" because "The combined area of the mainsail and jib shall not exceed 15.50m2". As has also been said "Only one spinnaker may be carried on board in any race." Therefore if you make the spinnaker your upwind sail, you are also stuck with it downwind. Doesn't sound a great idea really. |
Posted By: Strawberry
Date Posted: 21 Jul 05 at 7:31pm
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I think my question has been mis-interpretted. I mearly meant to spark a discussion as to what defines a spinaker, rather than say, any other headsail. I'm not planning on actually doing it. It's all hyperthetically (spelling???) ------------- Cherub 2649 "Dangerous Strawberry |
Posted By: ssailor
Date Posted: 21 Jul 05 at 7:54pm
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Yeh most of it is - i think the main defining point without going into
the rules is the unstable luff, if its got a wire running down from the
head to the tack its a jib! The majority if not all spinnakers also
have sail in front of the luff, as in if you drew a staight line from
the head to the tack there is sail to either side, whereas a jib
finishes along the line! - dunno if u get what i mean
------------- Any one in need of quality carbon fibre work (tillers etc) at decent prices! Int 14 Gbr 1244 'Nucking Futs' The New Port rule!!. |
Posted By: kasey3000
Date Posted: 21 Jul 05 at 8:00pm
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I think what really defines a spinnaker is simply that you hoist it for downwind and drop it for upwind.... like jib is defined inboard sheeted and genoa is outboard sheeted.....just when and how you set it ............it would be pretty interesting to see how a 21sqm jib would be though Kita ------------- 49er 908 |
Posted By: Strawberry
Date Posted: 21 Jul 05 at 8:00pm
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Yer, I get it. But you can get spinakers with wire luffs. ------------- Cherub 2649 "Dangerous Strawberry |
Posted By: kasey3000
Date Posted: 21 Jul 05 at 8:03pm
but they aren't quick with wire luffs !!!.....boring and slow  ------------- 49er 908 |
Posted By: ssailor
Date Posted: 21 Jul 05 at 8:33pm
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and surely with a wire luff they are just large headsails for downwind like on some of the yachts/tri's?
------------- Any one in need of quality carbon fibre work (tillers etc) at decent prices! Int 14 Gbr 1244 'Nucking Futs' The New Port rule!!. |
Posted By: kasey3000
Date Posted: 21 Jul 05 at 8:37pm
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what i don't gte with kites with wire luffs is.....how do they come down into the chute? is there a special system? ------------- 49er 908 |
Posted By: JimC
Date Posted: 21 Jul 05 at 9:59pm
Well you don't see them nowadays, but mine had 2mm diameter flex wire, so it really wasn't an issue. Of course nowadays you'd just use vectran or something. |
Posted By: Stefan Lloyd
Date Posted: 22 Jul 05 at 7:51am
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From a racing point of view, in general RRS 50.4 defines the difference quite precisely (except for your example of a Cherub). I quoted it in an earlier post. Basically, a jib or genoa is more or less triangular, while a spinakker is "fat" in cross section. Any other restrictions come in via class rules. So for example, while you might expect a spinakker to be made from nylon, there was experimentation with mylar film spinakkers for yachts in the late 80s (very pretty but they didn't really work) and some AC boats use spectra spinakkers of huge price. If you want a real example of muddied waters, consider the Code 0 headsail which were carried by a lot of VO60 boats. They measure as spinakkers, in order to get around a ban on masthead jibs in the class, but they "look like" big genoas made of laminate and are designed for close reaching. http://www.quantumsails.com/download/dispatches/Code_Zero.pdf - http://www.quantumsails.com/download/dispatches/Code_Zero.pd f is a good read. |
Posted By: pro wannabe
Date Posted: 26 Jul 05 at 6:58pm
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you couldnt really put any sail on a bow sprit for up wind /beating because you need a tight luff! but ive managed to get my spinnaker on my laser 2 to fly on a beat, but then its not a normal spinni, its longer and thinner, but still regulation size, if you get a semmetrical boat andn put the kite up and pull the pole down as tight as possible and pull the sheet in as tight as pos, then you can tighten up a fair bit! ------------- Your spinni aint as big as your mouth! |
Posted By: timnoyce
Date Posted: 26 Jul 05 at 7:05pm
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pro wannabe... you say that your laser 2 kite is regulation size yet
longer and thinner? it's a one design so surely it should be exactly
the same as all the others. not sure they'd be too happy at the nats
with an odd shaped kite to be honest
------------- http://www.facebook.com/bearfootdesign - BEARFOOT DESIGN Cherub 2648 - Comfortably Numb |
Posted By: JimC
Date Posted: 27 Jul 05 at 8:50am
I imagine what he means is that its longer and thinner than say a Fireball kite. The Laser 2 has a lot of (70s) Cherub in which is why the long pole and a better reaching capability than other equivalent boats. |
Posted By: Iain C
Date Posted: 27 Jul 05 at 8:57am
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Go on strawberry, stick a code zero on your cherub, we could do with a laugh... ------------- RS700 GBR922 "Wirespeed" Fireball GBR14474 "Eleven Parsecs" Enterprise GBR21970 Bavaria 32 GBR4755L "Adastra" |
Posted By: pro wannabe
Date Posted: 27 Jul 05 at 6:57pm
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dunno about nats but i like it the way it is, i can get round a whole corse without dropping it! ------------- Your spinni aint as big as your mouth! |
Posted By: LocoP
Date Posted: 27 Jul 05 at 7:36pm
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Strawberry - why do you need a definition of what a spinnaker is? Surely you know its the big yellow one sheeted off your transom!!! Code zero dont even think about it
------------- Get your heart racing |
. You'd need a bigger car just to put it in when its rolled up!!!