Does a spin lift leeward bow? And Hooter editorial

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.

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?

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.

I don't quite follow your comment about there always being a vertical component, could you expand on that?

A sail like a NORTH CODE ZERO or reacher or similar requires substantial amount of luff load to maintain sail shape. This high amount of luff load translates to rig compression and puts additional stress on the rig as compared to a relatively softly loaded spinnaker. The sail materials also make a difference on rig compression. The less stretchy reached and code zero sails also increase rig strain.

As to penalties: There is a far greater range of TWA (True wind angle) capabilities on a reacher compared to a spinnaker. The wider range increases the penalty to compensate for the additional use and MPA (Maximum projected sail area or at least potential) over the full range of the course.

LIFTING THE BOWS...? Sails with an acute angle of rake provide additional lift. Witness AUSSIE 18s where only their rudder is in the water at times downwind.

In my experience a flat spinnaker provides more lift than does a reacher or "hooter".

MM

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.htm

Clearly 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

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

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!).

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!

Hi Andrew, how is your spinnaker pole setup coming? Check out the notation just above the modification table.. It reads: For clarification: For class normally without spinnaker carrying a second one or carrying another headsail in a long distance race, apply both modification factors.
For class normally with spinnaker carrying one or more additional headsails, apply modification factor for each.
I interpret this to mean that if I carried two headsails such as a spinnaker and a reacher, I would take both the 0.955 hit for the 1st headsail and the 0.958 hit for the additional headsail. Can anyone shed more light on this?
Don Caldwell
Supercat-20 w/spin and/or reacher

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

Wouter,

Thanks for the very good article - it is recommended reading for serious catsailors.

Cheers,
Luiz

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

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

...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.

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.

What about the wave piercing designs then?

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

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?

If I understand the Brit's summary of the Finn's analysis, there is a net force pushing down on the bows from a spinnaker, but it is substantially less than if the same sail area was on a high aspect rig with the fore to aft CofE at the same distance from one end of the boat? Experience seems to contradict the interepretation of the numbers. Even rereading the article seems to say the same thing, that bows are flying and the boat feels steadier, but the numbers don't lie, so there is more pressure on the bows. In an effort to make sense of both I wonder if the explanation is that while some additional pressure is put on the bows the additional foward speed.... (does something causing the leeward bow to actually ride or float higher?) As I think about this more, I'm still having trouble with a net down force. If you observe the end of the spin pole properly preloaded or otherwise, it bends up as the loads increase. Although part of that is how it is supported and how the loads are applied, if there is a net down force it has to be applied at one of the 3 corners and its not happening at the clew or the tack. (loosen them under some load and see which way they go) Looking forward to some logical, factual input.

Wouter, I'm unable to find link to Bethwaite's article on your site. Is it there and I'm just not finding it?

Also, Wouter, my recent experience and Randy Smyth's article in White's book on spinnaker's indicates that although you can sail deeper with a spin, and you feel like you are going fast and you have flow over all sails, you are sailing too low. Under a spin you need to be sailing higher than what feels right, about the same as non spin boats, but going 'way' faster.

Todd, just because you can pitch pole with the spin up doesn't mean there isn't more force lifting the bows with a spin than without. There is a potential for considerable pitching moment if the boat is not trimmed properly

The direct forces at the clew, head, and tack of the chute are pulling forward, forward/leeward, forward/up/leeward (respectively) from the boat, thus not pushing the bows down. However, the force on the rig as a whole is acting 15, 20, maybe 25ft up the mast. This induces quite a moment in the system which is reacted by a couple that pushes the bows down and pulls the sterns up. The boat is in "pitching equilibrium" (for lack of a better description) when the force of the chute pulling up on the tack equals the force pushing the bows down. This is also helped along by the skipper and crew moving aft in the boat. The force of the skip and crew weight counteracts the upward force of the sterns.

Ultimately there must be a net down force for the system, otherwise the FAA might get involved.

You both gave some great explantions.

I KNOW that there is also upward force applied to the bows, most of the time actually. And yes, of course, my spin pole wants and does bend upward with the sail load of the chute.

I was just interjecting because earlier, the posts acted as if ALL the force was ONLY lifting the bows!

I too have some mast rake which is more than I ran without running the chute. Of course this helps also.

As Shannon stated, all the load, whichever direction, pulling on the mast somewhere above the base, will essentially also 'lever' the bows down some at times.

This has been a great discussion.

Todd Bouton
N6.0na +
#111

I would refer you to Frank Bethwaite's book page 401 in which he describes how 18 ft. skiff sailors use the lift from the spinnaker to control the height of the bow when sailing through waves. Just thought I would throw that in. I don't have a spin.