90% headsail

[ken003]

The only headsail I have is a 135%.  I would like to have something around 90% for heavier winds.  I have a quote from Cruisers Direct Sails which is probably a good deal.  However, The Sail Warehouse has ready made storm sails for half the price.  Their largest storm jib has luff-30', leech-23.6', foot-12.6' (145 sq ft).  This sail would not get a lot of use and we are cruising not racing.  Would sailing performance take a big hit by doing this?  Does anyone have the dimensions for a jib in the 80-90% range? The storm jib sail area is only 145 sq ft, which is equivalent to about a 50% jib?  Should I go with the Cruisers Direct sail?

Ken     

[Craig Illman]

Ken - I have a 90%. I don't know what it's dimensions are. If it was any shorter or the clew any lower, the inside track would really be too short. In over 12 knots of wind, I get plenty of power out of it and it's real easy to tack.

Craig

[Stu Jackson]

Ken,

Craig is right, the position of the track is very important in your selection.

We have both an 85% and a 110%.  The 85% is actually our original 110% that was cut down because of UV deterioration of the protection sunbrella.  The 110% we bought in good condition from a fellow C34 owner.

We use the 85% during the summer high winds here, and the 110% for winter lighter winds and summer racing.  The first two pictures show our 110%, the second two are "Wind Dragon" and "Amandla" in last week's Rites of Spring Race - they have 130%s.

The important part is the position of the clew.  For both of our sails, the clew position is relatively high compared to our racing brethren here, who almost all use 130%s with long leeches and low clews.  And, both our jibs require that the jib fairlead car be placed as far forward as possible on the track to get a good closed leech set; anything further aft opens up the leech, depowering the jib.  One advantage of a high clew is good visibility forward for going anywhere, racing or cruising, but the higher clew does affect flow over the sail/hull combo - like decksweepers get the hull and jib lined up very well - that's why racers keep 'em low.

You can check this clew height distance by looking around your docks at how high the clew is when the sail is furled on different boats (although you won't know the size of the jib (%) when they're furled).  Craig properly notes that the lower the clew, the further forward the car has to be on the track.  In our case, even the higher clews require that forward position.

So, regardless of size, the geometry of any given sail is extremely important for you to know.  Two 110% jibs can have the same LP but be cut differently with higher or lower clews, with longer or shorter leech dimensions.  I do not have the dimensions of our sails, they're not Catalina OEM's, but were both made here by a local loft, Leading Edge Sails, now out of business (but great sails).

Given our experience here, with our C34 and two earlier boats (C22 and C25), our 85% is fine for strong winds.  I have only had to double reef a few times in over twenty five years.  Our 85% and single reef works fine in winds up to 25-30 apparent, then the double reef comes in.  Then the jib car gets moved back.  Then I turn downwind...

Given your choice of a 90% or 50%, I would recommend the 90%.  If you want a real storm jib, consider the ATN gale sail, if you think your sailing conditions would warrant it.  For "regular" higher wind sailing, the 90% would be your best bet to keep the boat moving properly.

[Ken Juul]

In general the area of the head sail can be found by A=(Luff*Lp)/2.  Lp is a % of the J measurement.  A 100% sail, Lp= J.  For a 90%, Lp would be 0.9*13.5=12.5.  The max Leech length is approx the square root of Jsquared +I squared.. J=13.5, I=44....or 46'.  You can't use all that because of hardware so figure a max leech of 43.  Doing the math that gives you a luff of around 40, foot around 13, and area in the 250-260 sqft range. 

A good sail maker can play around with the dimensions to give you a sail that fits your needs and the boat.  You want a sail that is to be used when the wind is blowing to set properly, otherwise it will flog itself to death.

[Stu Jackson]

As far as LP alone, consider the attached sketches.  Same LP, but the clew is much higher on one than another.  Basic trigonometry of different triangles.  Just click on the link and click on the "Open" box.

PS  I just learned that Robert Gainer passed away recently.  He wrote: "The LP by the way also has nothing to do with the height of the clew. A high cut reacher with an LP of 150% has the same LP that a 150% deck sweeper has."

Another way to think of it:  take any jib and hoist it upside down!  The LP is the same, but...the clew is MUCH higher.

[Stu Jackson]

Here's a link to an earlier thread in much th same vein:  http://c34.org/bbs/index.php/topic,3470.msg19156.html#msg19156