genoa dimensions

[spirith34]

Hi all
Looking at buying a second hand headsail
what would the dimensions for a 100% and 130 % sail be
curently have a 1986 c34 std rig witha 155% headsail
most of a wind over here in Australia is always over 15 knots
ave is 15-20 knots furling the 155 will not go to windward
so am willing to try another headsail

[Mike Smith]

Need more info:

1.  Do you have a fin or wing keel?
2.  Do you reef the main? 
3.  Do you use the traveller?

With a constant 15-20 kts you may need a 110!

Mike

[Jon Schneider]

It depends on the position of the clew (and therefore the design of the sail), but you can figure that a 100's foot is about 15' and a 130's is about 18'.  You need to measure your own luff, but 42' is good estimate if you're searching online. 

Mike, I'm curious... what do your questions have to do with measurements for a jib?

[dave davis]

You asked for the sail size of a 100% and a 130%. Since sail size is measured and related to the "J" dimension of your boat, your C34 has a "J" dim. of 13.5 feet. To keep this as simple as I can. If your sail is 13.5 feet as measured from the clue to the least perpendicular(LP) on the Luff.that means it is a 100% headsail. Now if you want to have a 130% headsail, you multiply take 13.5(J) times 130% and you get 17.55 feet(LP)
You can often find the dimension of a sail as Foot,Luff, and Leach. These numbers can vary depending on the sailmaker. Sorry for any confusion I may have caused.
Good Luck, Dave

[Mike Smith]

Jon -

He may not need a new jib.  His problems are:

A.  He can't go to weather
     Re 1.  You can point higher with a fin keel versus a wing keel.
     Re 3.  You can point higher by adjusting the traveller to bring the boom to centerline or higher.

B.  He is in constant 15 - 20 kts
     Re 2.  Reef the main for overpowered conditions.  You'll sail more upright and be able to point higher

No improvement - then consider a smaller headsail.

Mike

[Stu Jackson]

spirith34

Hi, and welcome.  Here on SF Bay it blows pretty hard, 'specially during the summer.  The racers here have a max head sail of 130%.  We have two head sails, a 110 and a 85-95 (old 110 cut down due to UV cover deterioration - long story previously posted).  Unless racing, we use the 85-95 during the summer and our "big" 110 during the lighter winter period.  Even with the 110, we reef the main before 18 knots of apparent wind, and the boat sails very well.  That's what Mike was getting at, I believe.  We have successfully raced with our 110 against folks with 130 headsails, but our handicap rating is very high, with out fixed three blade prop, roller furling, tack way high off the deck.

If you're going to be sailing in the winds you describe, I would strongly urge you to consider a smaller head sail, given that our boats are generally driven by the jibs.

[Ron Hill]

Spir:  I have a standard rig and have changed out from the Hood 915 continuous line to a Hood 808 line drive.
The most important dimension of a sail (to me) is the luff length so it fits properly on the furler.  I have a sail that has a luff length of 42ft 7 1/2inches and has fit on both units.  
What I'd suggest - is that you measure your present sail luff and then add or subtract a few inches to that luff length to meet your own desires.  When buying a used sail the % is going to be what's available!!
If your winds are so strong you might consider a laminate sail.  They hold their shape a bit better.  
A thought.    

[spirith34]

thanks for all your comments
just to put one or two people at ease
when i furl the headsail to about 2/3 of original size(with the clew at the start of the front shroud) the luff is very wide
this is preventing the pointing aspect ( i think any way)
the main is reefed to the secong reef point
main sail is just average condition for age (so i am told)
the head sail is new ( 1 season old) when i purchased boat
my thoughts were to remove the 150% sail and put away for lighter wind conditions and buy another headsail
thanks again for the help
graeme

[Jon Schneider]

Graeme, you're clearly right on in your assessment that you need a new, smaller headsail, given the configuration that you've just described.  One thing you might want to test is if reefing your headsail a bit less so that it overlaps the main will help.  In reefing your 150 so extremely, three things happen, which I'm sure you know: 1) the luff shortens so you lose topsail power and air-dumping ability (i.e., it's more difficult to control the shape of a heavily-reefed headsail); 2) you have a heck of an airflow disturbance caused by the large roll of sail wrapped around your furler; and 3) the lack of overlap with the main creates an air disturbance ripple at the mast (i.e., the lack of overlap in the slot creates a little "storm" along the leech of the jib).  There's nothing you can do about the first two without getting a smaller jib, but you can minimize the third by reefing a touch less. 

Additionally -and you've probably tried this, but I'd be curious to hear your experience- you might want to try reefing the main less.  Again, you're losing pointing ability by so shortening the main.  I know it sounds strange that I'm recommending more canvas (a little) than you currently deploy, but I've found that bad sail shape (which happens when you reef) will mitigate the lower-power benefits of less sail area.  BTW -and I hate to say this- you might investigate a new main while you're at it.  I wasn't sure what you meant by "average condition for [its] age."  Often that's code for pretty bad condition.  In fact, I equate "average" with useless.  If this is the original main, it's at least 10 years past its prime, and it probably wasn't a very good sail to begin with.  I've found that people tend to underestimate the importance of the main on our rigs because it has less sail area than the genny, but I've discovered that the condition of the main is crucial in balancing and driving the boat.  It's not so much about speed, but control and, thus, pointing. 

And just to be completely thorough in curing the lack of pointing ability, have you tuned your rig?  Can you point better on one tack than the other?  Do you have headsail sag due to the stays being too loose? 

Just some thoughts.  Of course, you're right that the biggest improvement will come from acquiring a smaller headsail, but I would think about the other elements of overall trim as well.