Setting The Pole Height on your Spinnaker

Dave = Campaniello=20 is the newest salesman at UK Sailmakers in New York. Before = joining=20 UK, Dave was the Director of J/World in Key West - one of = the=20 premiere schools for racing sailing in the United = States.=20

Too many times have I been racing on a boat where = someone=20 says "The clews aren't even- raise the pole." Well, yes, = this is=20 true - the clews should be even - if you are using the right = sail in=20 the right conditions at the optimum wind angle, which is not = always=20 the case. When I ask a lot of people how the break looks, = more often=20 than not they are not, they are not so sure what I am = talking about;=20 the usual response is "fine". The correct response is = "even". What=20 that person is not aware of is that I am asking him if the = pole=20 height is right. Here are my tips for getting the pole = position=20 right when trimming the spinnaker.

Let's start out with a few truths and = untruths.
1. The=20 pole position largely affects sail shape - True.
2. The = height=20 of the pole is strictly determined by the height of the = leeward clew=20 - False.
3. The pole height controls the break of the = leech,=20 which helps induce the correct, designed sail shape when set = right -=20 True.

Now, lets establish a few important design = aspects.=20 Many of you have heard the term "a profile like a beetle's = back"=20 when describing spinnaker shape - starting round at the top = and=20 getting straight and vertical as you go down (see photo = above). In=20 order to achieve this modern shape, your spinnaker, when = folded in=20 half and laid on the loft floor, is cut with a distinct "S" = curve=20 along the luffs (see below). Providing the correct pole = height=20 enables this curve to 'set' properly when being flown, thus = giving=20 us that desired shape.

Let's analyze some = different pole=20 height settings. With the pole too low, you'll be trying to = pull=20 that curve too straight. Instead of billowing away from the = boat,=20 the shoulders will curl over, causing the top of the = spinnaker to=20 break early, which causes the trimmer to tighten the sheet=20 prematurely. The end result is an over-trimmed (and = over-flattened)=20 spinnaker, which is choking off flow of air around the main = as well=20 - all bad things.

As you raise the outboard end of = the pole,=20 you see the break change - instead of the breaking at the = top, it=20 moves down and evens out along the luff, as the top of the = sail=20 opens up. The break becomes even, indicating a properly = shaped sail=20 - at least in the front. The easy way to remember this is = "move the=20 pole to the break." If the sail breaks high, raise the=20 pole.

If you have the pole too high, the opposite = will=20 happen. The shoulders will billow out too far- causing the = bottom of=20 the leech to break first- and the top to break late. This = causes the=20 trimmer to want to over-ease in order to get the top to = break. The=20 end result is an under-trimmed sail, with too much leech = twist -=20 allowing the air to escape over the leech instead of being = directed=20 to the foot, where you want it while sailing downwind. =

What=20 about the inboard end? Well, that's easy. One of the pole's = jobs is=20 to extend the sail as far away from the rig as possible. The = inboard=20 end is adjusted to match the outboard end, strictly to keep = the pole=20 perpendicular to the rig, therefore keeping it as extended = as much=20 as possible.

On the sheet end of things- the sail, = remember,=20 with the pole too high was inherently over-trimmed- so as = the pole=20 is raised, the sheet can generally be eased. And as the pole = is=20 lowered, the sheet generally will need to be trimmed, as the = luff=20 closes up top. An easy way to remember all this- " Down and = in" or=20 "up and out". Another consideration here is that the guy = must be=20 adjusted when raising or lowering the pole- if we are to = raise the=20 pole the guy must be eased, or the pole will oversquare. = Again, "UP=20 (on the pole) and OUT (on the guy and sheet). If we lower = the pole,=20 it will undersquare. Therefore, DOWN (on the pole and IN (on = the=20 sheet and guy). I often use the Phrase of "reigning in" the = kite=20 -The sail has gotten too far away from the boat -the guy was = eased,=20 so the pole end raised up a little- then the trimmer had to = ease=20 more because the luff wouldn't break- but when it does the = whole=20 thing is about to luff- so the guy gets eased again, and so = on and=20 so forth. Now the sail is truly ballooning, and needs to be = "reigned=20 in". AKA over-eased, under-squared and under-trimmed. This = is a bad=20 combination- a high center of effort, a low amount of = pulling force=20 due to decreased exposure to the breeze - bad and really = bad. This=20 is an occurrence I see way too often. If we pay attention to = the=20 subtle but important detail of the break, we will see that = our clew=20 heights often end up even- when the sail is being used in = the proper=20 range of conditions.

But what then, when we are not = using it=20 in the ideal conditions, such as a one design class where = you are=20 only allowed one sail, or when the breeze changes and you = are not in=20 a position to do a peel?

Lets look at the high wind = side=20 first. As the breeze increases, we sail deeper- squaring up = more,=20 and easing the sheet and consequently raising the pole to = get the=20 right break. Anytime a spinnaker sheet is eased - the clew = goes out,=20 but it also goes up. Now we have a sail that has a clew that = is too=20 high - as the sail we have up is designed to be trimmed with = the=20 clew lower. The end result is an asymmetric shape that = allows the=20 air to flow from luff to leech. The solution here is not to = raise=20 the pole further- that will only make it worse, since it = will cause=20 the trimmer to want to ease even more. This is where a twing = on a=20 spinnaker sheet becomes very valuable. In addition to = keeping the=20 clew lower, it will help increase the boats stability by = controlling=20 the oscillations of the sail. On lager boats, many times the = solution is to trim it off what was the lazy guy instead of = the=20 sheet- until it is time to gybe, when you switch back to the = sheet=20 on a twing.

We said that if the clew is high, the = air flows=20 luff to leech- sound familiar? It should- especially if you = use an=20 asymmetric spinnaker or trim a headsail. As the breeze gets = lighter,=20 we sail higher angles. The guy gets eased out and the pole = goes=20 forward and consequently, wants to go up. The sheet gets = trimmed in=20 and the clew goes down. What often then happens is the clew = ends up=20 lower than the pole, wish is just plain 'ole bad. If we = lover the=20 pole enough to get it lower than the clew, now we have that=20 asymmetric shape that we see screaming past us on the sprit = boats- a=20 low tack, with a high clew to induce that luff to leech = flow,=20 without choking off the newly established flow around the = back of=20 the main. Not the best way to use your kite- but remember, = you were=20 supposed to do a peel to a reaching sail five knots ago.=20