| Does a spin lift leeward bow? And Hooter editorial #13535 11/26/02 11:10 AM 11/26/02 11:10 AM |
Joined: Jun 2001 Posts: 64 Sandy, UT SteveBlevins OP
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Posts: 64 Sandy, UT | When I was trying to evaluate spin vs Hooter, for me it came down to 2 issues: Stress on the rig and lift of the leeward hull. What got me into spin sailing was an article in Performance Sailor starting off about 'what gets you to beach first, corrects out DFL, and puts a permanent smile on your face? A spinnaker!' and the observation by a fellow P-19 sailor that sailing with the spin just pulls the leeward hull 12" out of the water. So, I tried it for about $400 (Randy S sold me a used spin for $250) and found the reports true. So, when it came time to update the rig I talked to the West Coast guys that had Hooter's and Calvert Sails. The consensus was that it does add stress to your rig, which may not be as serious as I thought, but in a good blow the spin can pull your whole boat out of the water, and my knee jerk reaction was to not add to that load. And I was told by Calvert Sails that the Hooter would tend to press the bow down and the Hooter sailors out here said the same thing. The Hooter sailors out here sail Nacras or similar so a little bow pressure doesn't hurt. But the last thing a P-19 needs going downhill is something driving the bows down. Now, I do know that a spinnaker does help pull the leeward hull out of the water, and I assumed it was because of the fullness of the sail compared to the Hooter. But now after reading the Assymetric thread and reorganizing facts and semi-facts, the leeward hull lifting thing may be due to the angle of the luff of the spin, in which case similar results could be expected of a Hooter. I have never sailed a Hooter, so all I 'know' about Hooters is from experienced but non-racing sailors and 'experts' . So I now question what I 'know' and throw this issue out, not seeing any comments on this issue in the years I've followed this forum. Additionally, as far as cost, ease of handling, and windage go, I believe it is a wash. There are ways to deal with each drawback of each system. It does not cost $3000 to get into a spin, and I doubt any but a very few spent over $1000 to get into their first spin. Hooters ought to be allowed to compete and appraised. Maybe the ISAF hit is justified and the sail is so much faster but the techniques aren't being used to fully use it. Maybe it has conditions in which it is outstanding and conditions in which it is a substantial detriment. But if it has the potential to make us go faster and improve our understanding of the physics of wind and sail, as catsailors we need to be breaking down our comfort zones and learning some more. Obviously when you have an organization there are political considerations, they don't have to be evil, and they may need to change in the light of new ideas. Sometimes in these extended discussions I find myself aligning myself with what I like or believe and discarding the rest so that I get into a cycle of reinforcing what is comfortable to me and completely rejecting and tuning out the rest. I would sure hate to be 70 and find that sailing a Hooter improved my enjoyment of sailing and I could have done that when I was 40. | | | Re: Does a spin lift leeward bow? And Hooter editorial
[Re: SteveBlevins]
#13536 11/26/02 11:56 AM 11/26/02 11:56 AM |
Joined: Aug 2001 Posts: 1,307 Asuncion, Paraguay Luiz
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Posts: 1,307 Asuncion, Paraguay | Steve,
There is no need to complicate things:
Any headsail (jib, spi, hooter) lifts the bow, much like a windsurfer's sail inclined to windward. The differences in sail shape are less important then the relative positions of the sail's extremities.
The tack, hoist and clew of a sail define a plane. In the mainsail, this plane is vertical (or as inclined as the mast is raked aft).
In any headsail, this plane is inclined to windward, so the sail thrust always has a vertical component lifting the boat.
Placing the headsail further forward increases the leverage of the vertical component and raises the bow higher with the same sail thrust.
Simple, isn't it?
Luiz
| | | A question about rig loading by a hooter vs. spin
[Re: Luiz]
#13537 11/26/02 12:08 PM 11/26/02 12:08 PM |
Joined: Oct 2002 Posts: 50 Farmington, Utah thouse
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Posts: 50 Farmington, Utah | I think I follow the last post regarding bow lifting or loading. However, I'm not sure I understand why folks say a hooter loads the rig more than a spinnaker. Indeed, (it seems to me) both can be sheeted hard or eased. Indeed, it seems both load the mast, rigging, sheets and front beam. So why it there more loading of the front beam when using a hooter, than when using a spinnaker...or is there more loading....??? Thanks, Tom H. | | | Ahh but is isn't that simple ! Read this
[Re: Luiz]
#13540 11/26/02 12:56 PM 11/26/02 12:56 PM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
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Posts: 9,582 North-West Europe | Surely an angled luff produces vertical lift forces trying to lift the bows up BUT it also produces horizontal thrust forces which in turn are trying to push the bows down. What will the net result be ? Read this analysis made by a Finnish sailmaker. http://www.sailingsource.com/cherub/aero.htmClearly guys this issue is more complex than we would like to believe. I can tell you from my own analysis that the diving is not only the result of a balancing act between thrust and lifting but also the course is an important factor. Typically spinnakers and gennakers sail noticably deeper than spi less boats and this more instrumental in reducing dive tendency than the headsail lifting characteristic is. Sorry Luiz, it's not that simple. Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Re: Ahh but is isn't that simple ! Read this
[Re: Wouter]
#13541 11/26/02 01:13 PM 11/26/02 01:13 PM |
Joined: Apr 2002 Posts: 591 Bradenton, FL Sycho15
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Posts: 591 Bradenton, FL | So... he's saying that the sails themselves are generating lift, but since they are also pulling the boat forward from so far above it, they are "pushing the bows down" (because they are, in effect "tripping" over the bows"). This is why lighter crews have less tendancy to pitchpole? Because the entire boat has less weight and is therefore more easily driven (or accellerated) by the sails? Sounds good to me, I only weigh 145lbs and I usually sail solo! I guess that means I'm just more likely to capsize than to pitchpole Why don't we settle this once and for all. Someone give me a spinnaker pole, a spinnaker, and a hooter. I'll go sailing as much as I can for a year and get back to you with the results
G-Cat 5.7M #583 (sail # currently 100) in Bradenton, FL
Hobie 14T
| | | Re: A question about rig loading by a hooter vs. spin
[Re: thouse]
#13542 11/26/02 07:06 PM 11/26/02 07:06 PM |
Joined: Jun 2001 Posts: 12,310 South Carolina Jake
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Posts: 12,310 South Carolina | The hooter requires fulltime tension on the luff, even when furled, and adds to the mast compression at all times (which is then carried to the forward beam). I also believe that the hooter can be carried a lot higher than a spinnaker and wish it would be more fair to run either (I remember a N6.0 at RTI that carried both! - that must have been a painfull portsmouth hit!).
Jake Kohl | | | Re: A question about rig loading by a hooter vs. spin
[Re: Jake]
#13543 11/27/02 12:08 AM 11/27/02 12:08 AM |
Joined: Jul 2001 Posts: 364 Andrew
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Posts: 364 | Actually, the rating hit for carrying two or more additional headsails, based on actual race results, is less than that for carrying only one. Apparently, the extra mess on the boat, parasitic drag, and the hassle of dropping the spin to raise the hooter (and vice versa) takes a bit of the benefit away. Checking the mod table now, it remains: .955 hit for carrying extra headsail in a distance race, and .958 for carrying two or more.
sail fast!
Andrew Tatton
Nacra 20 "Wiggle Stick" #266
Nacra 18 Square #12
| | | Re: A question about rig loading by a hooter vs. spin
[Re: cappydec]
#13545 11/27/02 01:58 AM 11/27/02 01:58 AM |
Joined: Jul 2001 Posts: 364 Andrew
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Posts: 364 | I have the pole; it's a 100% carbon windsurf wave mast @465 cm, official weight is just under 4.7 lbs, and official cost was $95. Base fitting just needs some more grinding for a good interference fit; the tip already has a thick aluminum liner (dead Gary Fisher handlebar section, about 2 1/2" long) Wested in. I have some ideas for the strut(s); one recommendation was to make them 12" long and about 30 degrees apart, but I'm thinking a bit longer. I want the high point of the pole to be as high as possible, while still taking max advantage of the 15' length to lower the hound on the mast and "lay" the chute back for more bow lift a la the skiffs. God knows the P-19 needs it!
As for the "clarification:" I know it has been scored the other way, with the lesser hit for two sails than for one. I also know that I haven't seen Beuerlein carry both headsails in quite some time...it's very possible that they began scoring according to the "clarification" and the 2-headsail rig lost a bit of its "charm", shall we say. Anyway, if you have facilities for welding/otherwise fabricating aluminum, please email me. thanks, and sail fast
Andrew Tatton
Nacra 20 "Wiggle Stick" #266
Nacra 18 Square #12
| | | Excelent article - thanks!
[Re: Wouter]
#13546 11/27/02 08:01 AM 11/27/02 08:01 AM |
Joined: Aug 2001 Posts: 1,307 Asuncion, Paraguay Luiz
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Posts: 1,307 Asuncion, Paraguay | Wouter,
Thanks for the very good article - it is recommended reading for serious catsailors.
Cheers, Luiz
Luiz
| | | I got a few more articles like that go to :
[Re: Luiz]
#13547 11/27/02 08:21 AM 11/27/02 08:21 AM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
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Posts: 9,582 North-West Europe | I got a few more articles like that go to : http://www.geocities.com/kustzeilen/and scroll down Especially the article by Tom Speer, Jim Boyer and the article by Bethwaite about the 49-er are interesting. And lets not forget JSD with "Airfoils and airflow" In the future I hope to update the page with several more links to interesting articles. Have fun. Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | ???
[Re: Wouter]
#13549 11/27/02 08:53 AM 11/27/02 08:53 AM |
Joined: Jul 2001 Posts: 2,844 42.904444 N; 88.008586 W Todd_Sails
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Posts: 2,844 42.904444 N; 88.008586 W | I'm currently in a 12 step program for spinnaker flying.
My name is Todd Bouton, and I fly a spin on my cat.
I agree with most of what's been said, especially Wouter's comments.
Before I got to his post, I didn't agree with this major lift thing, especially since:
I'VE STUFFED (PITCHPOLED) AND CAPSIZED MY CAT, MORE THAN ONCE, AND IT WILL PROBABLY HAPPEN AGAIN! IF THERE'S ALL THIS LIFT (SINCE THERE IS AT TIMES), THEN WHY DO PEOPLE STUFF A BOW FLYING A CHUTE?
(I'll quit yelling now) And I've seen Many, that's right many, others do it also. PI Sailing on their I-20 in Rough Riders, etc.
It ain't ALL Lift!
Todd Bouton N6.0na+ #111
F-18 Infusion #626- SOLD it!
'Long Live the Legend of Chris Kyle'
| | | And they are also good...
[Re: Wouter]
#13550 11/27/02 11:54 AM 11/27/02 11:54 AM |
Joined: Aug 2001 Posts: 1,307 Asuncion, Paraguay Luiz
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Posts: 1,307 Asuncion, Paraguay | ...but Tom Speer's article is too complicated and Jim Boyer's is practical, but too simple. JSD is my preferred. Two years ago I printed the entire book hoping to learn how to fly ... and then started to build the Catri.
Luiz
| | | Mea culpa
[Re: Todd_Sails]
#13551 11/27/02 12:17 PM 11/27/02 12:17 PM |
Joined: Aug 2001 Posts: 1,307 Asuncion, Paraguay Luiz
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Posts: 1,307 Asuncion, Paraguay | Todd, It's my fault . The lift is there, but the torque of the sail's thrust also has to be considered (and there is even more to consider - but you can read about it in the articles indicated by Wouter). Focusing in the torque only: The sail's thrust can be considered to be acting in the center of the sail area, which is HIGH. The torque generated by the thrust tends to bury the bow. What keeps the boat from pitchpoling is the bow's flotation. Lack of flotation there is a big problem. The effect of the torque generated by the sail's thrust is usually greater then the effect of the lift, thus your initial confusion. Super simplified conclusions: 1-A big foresail increases the risk of pitchpoling, due to the higher thrust generated by the greater sail area creating a pitchpoling torque. 2-A big foresail MAY reduce the risk of pitchpoling, if it is placed sufficiently forward for its lift to generate a torque which is bigger then that of the sail's thrust. This is the reason why 49rs have loooong bowsprits... I hope it helps.
Luiz
| | | Almost right !
[Re: Luiz]
#13553 11/27/02 05:50 PM 11/27/02 05:50 PM |
Joined: Jun 2001 Posts: 9,582 North-West Europe Wouter
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Posts: 9,582 North-West Europe | all yes, BUT that diving is in turn counteracted by the fact that the craft sails deeper downwind. Why this is is more complicated.
However I too noticed that a spi boat sailed well has less tendency to dive than a spi-less driven well too (often meaning at a higher angle much closer to reaching)
Wouter
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands
| | | Wave piercing - it helps
[Re: Jacques]
#13554 11/28/02 08:28 AM 11/28/02 08:28 AM |
Joined: Aug 2001 Posts: 1,307 Asuncion, Paraguay Luiz
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Posts: 1,307 Asuncion, Paraguay | Jacques,
The wave piercing design has to do only with the bow shape above the water line. Its only effect is reducing the difficulty for the bow to emerge after burying. For bows with equal volume, this is the only difference.
Is this what you wanted to know? Or did I miss the point?
Luiz
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