Wednesday, November 21, 2007

Main & Jib Sails




“SAILING TO WINDWARD IS AN ART AND TO A LARGE EXTENT, IS WHAT SAILING IS ALL ABOUT”.

Sailing to windward well even dictates the shape of the boat, e.g. a sloop rig rather than a catboat rig or gaff rig.


MAIN SAIL

New sails were ordered from Raudaschal sails, Toronto (owner Heider Funk) in April/1986. I believe they are now under new ownership and supply North(?) sails. Heider was quite involved with Jack Payton in developing the split jib for the KERRY DANCER. The new mainsail had an increased roach and had adjustable battens in the top two battens pockets, with velcro fasteners. This feature allowed one to apply tension to the battens in light winds which would apply camber (Maximum camber is sail depth of approximately 18% of the chord length for a very powerful sail) to the sail and in strong winds, the battens were not tensioned (Minimum camber is a sail depth of approximately 5% of the chord length for a very flat sail), which gave you less powerful sails, ideal for strong wind conditions.









The adjustable battens really work as I remember on numerous occasions visiting various groups of sailboats, which were unable to move because of the light winds yet the KERRY DANCER could still move reasonably well in the light winds.


(See information on adjustable battens further on this post for more details on why they can be very effective)

The old main sail was cut down to the first reef points and the top batten was changed to velcro adjustment. The new sail, even with the increased roach, was much preferable to the cut down old sail because of the impact the traveller had on the heeling, as you never knew when the wind would decrease in velocity and you would have to brush against another boat, in light winds, with a much less powerful sail, not suited for light winds.

An interesting observation is that, in my opinion, the KERRY DANCER sailed better in stronger winds with the combination of the new mainsail, even with its increased roach, and the traveller than it did with the old cut down mainsail (which was even better than any reefed mainsail) and no traveller.

VERY INTERESTING INDEED!!!




ADJUSTABLE BATTENS


Our longest adjustable batten with an overall length of 64 1/2"







It is .100" in thickness and .740" in width which makes it very limber.



The deflection of the batten is controlled with an adjustment flap on the outer end of the batten pocket which is fastened with velcro.


















The batten when adjusted for high winds is deflected by compressing the end only 1/2" which results in defection of 5% of 64 1/2" = 3.23".







Amazing how such little compression results in significant deflection. Also shows that if you are out in strong winds be sure to slacken off the compression on the battens or you could have more power than can comfortably handle.


























In light winds, the batten is fully tensioned resulting in a compression of 5 1/4" which results in a deflection of 18% 0f 64 1/2" =11.61". This camber has a significant impact of the power of the sail. You will probably find that when other boats are just sitting in one spot in light winds, you will have sufficient power to manouver when they cannot.







When utilizing adjustable battens on your craft ensure that they are limber enough for easy adjustment. Many boats that have adjustable battens have battens that are too stiff (THICK) and they cannot adjust their sails to the current wind strength, subsequently they find that they are more likely to fall into holes in the light winds

You might have to slacken off your mainsail boom outhaul to fully realize the impact of your adjustable battens.


This concept also applies to your jib sail. In light winds, move your jib sheet fairlead forward to create a more powerful sail.


The only downside to having adjustable battens is that sometimes the wind is so light that when you come about the boom swings over to the other tack but the defected sail stays on the original side. A quick pull on the boom quickly corrects this problem.




SPLIT JIB

Since most boats go downwind at relatively the same speed unless they have an advantage of a whisker pole or spinnaker, the split jib is a real advantage to the KERRY DANCER, especially if you have a whisker pole that allows you to control the height of the clew.

SPINNAKER

My experience with a spinnaker on a KERRY DANCER has been less than ideal. One of our club members tried a spinnaker on his KERRY DANCER and quickly proceeded to break the mast at the spreaders. So, I wouldn’t advise installing a spinnaker when the split jib should perform the same function without jeopardizing the boat. Operating a spinnaker on a very limber fibreglass mast, without a backstay, is asking for trouble.

WHISKER POLE

The split jib is a great innovation to give you an advantage downwind if it can be properly controlled with an adjustable whisker pole that you can raise or lower to get the split jib into clean air.
The whisker pole uphaul line attaches, with a sister clip, to the top of the outer end and the downhaul attaches to the bottom sister clip. With the uphaul and downhaul controls, you can fly the split jib as you would a spinnaker, tensioning the luff.
The whisker pole is stored in its collapsed state in a cutout in the styrofoam floatation under the starboard seat.


WIND INDICATOR

Nowhere has it been mentioned how critical a good wind indicator is to achieving good windward performance. Others manage to sail well with wind indicators on their shrouds or a ribbon from the masthead and I compliment them on their ability to read the wind. However, a WINDEX 15, with the vanes set to the appropiate angles for a KERRY DANCER, allows a helmsperson to notice and adjust for the slightest change in wind direction (THE WIND IS NEVER CONSTANT- THE ONLY THING CONSTANT ABOUT THE WIND IS THAT IT IS CONSTANTLY CHANGING). A characteristic of the most proficient sailors is that they monitor the wind direction frequently.







WIND INDICATOR MOUNT FOR MAST














HALYARDS




The original halyard tails were 3/8" three strand dacron eye spliced to 1/8" 7x19 stainless cable with a thimble nicropressed onto the wire end. They were replaced with 5/16" dacron double braid eye spliced to the thimble nicropressed on the wire end.


The new halyards have worked well for several years with the exception that occassionally the main halyard would hang up on the mast's thru bolts when the mainsail was being raised. Then you would have to lower the mainsail a bit and attempt to raise the mainsail again. Another problem was that the sister clip on the end of the main halyard would not pass thru the retainer on the mainsail top pulley, consequently the main halyard could only be removed from the mast by cutting off the sister clip and nicropressing on a new sleeve when the main halyard was re-installed. As a result the wire portion of the main halyard kept getting shorter and shorter which resulted in the rope tail not being able to be attached to the sister clip when the sail was removed (to prevent the halyard from swaying in the wind).


In an effort to solve this problem, the main halyard will be tail spliced to a new length of 5/16" dacron double braid.







SECRETS OF THE TAIL SPLICE REVEALED

















JIB HAYARD TOP PULLEY



Within a year of installing the new jib sail, it was found that the material had stretched sufficently that a tight luff could not be accomplished. This was the result of too much sailing in strong winds The halyard pulley was changed so that the pulley was above the the forestay (not part of the forestay) which resulted in the ability to tighten the luff properly. Originally the forestay was attached to the pulley's frame and then to the hounds.























Why the jib halyard cannot be removed without disassembling the jib halyard top pulley










IDEAL SAIL TRIM


SAILING TO WINDWARD
These two sketches ( RIGS and RIGGING by Richard Henderson -page 187) outline idealized slots with proper trim and twist for light and medium winds for beating to windward.The best way to check your sail trim is from another boat off of one of your stern quarters or even standing on shore (It is difficult to evaluate your sail trim when you are on the boat being evaluated.) An even better approach is to capture the sail trim state with a camera.













Once you have captured the details of your windward sail trim, the big question is how you are going to use that information.






A. Blame your poor windward performance on the design of your craft. ( if the boat designer had wanted your boat to perform better, he would have added the necessary controls when the boat was made.)

OR

B. Work out a plan to add each control that is lacking over a period of time that is compatible with your financial and time resources.


WHAT CONTROLS ARE NECESSARY TO ACHIEVE IDEAL SAIL TRIM??

THE ABILITY TO CONTROL THE FOLLOWING FUNCTIONS IS ESSENTIAL TO ACHIEVE IDEAL SAIL TRIM

#1 mainsail leech tension (low in light winds- high in strong winds)
#2 jib sail leech tension (low in light winds - high in strong winds)
#3 mainsail foot tension (low in light winds - high in strong winds)
#4 move jib sheet fairlead to inboard position for light winds
#5 move jib sheet fairlead to outboard position for strong winds
#6 move genoa sheet fairlead to inboard position for light winds
#7 move genoa sheet fairlead to outboard position for strong winds
#8 move mainsail sheet anchor to above centerline (to windward) for light winds
#9 move mainsail sheet anchor to below centerline (to leeward) for strong winds

Ideal sail shape and trim for close-hauled sailing depends, of course, on the weather conditions, especially on the strength of the wind.


On a beat the camber and twist of a boomless headsail is easier to control, because the sheet tension is then pulling the clew away from the tack and spreading the two corners apart.
This greater controllability of the headsail shape means that the jib's leech can be made to conform better with the mainsail's vertical curve, and the slot can be optimized from head to foot. Notice that in both sketches the slots are fairly uniform from head to foot, but the sails have been flattened with less curvature vertically as well as horizontally in the medium breeze. This results in more forward thrust, better ability to point, and less heeling. The shape is achieved by tensioning the luffs and tightening the sheets while moving their leads farther to leeward. The mainsheet lead is moved with the traveller, and the jib's lead is transferred to a rail track. As the wind increases, the jib's lead is moved further aft to increase the upper leech and widen the slot to reduce heeling. In light winds, the sails are given more vertical curvature and camber to increase their power. The mainboom is on the boat's centerline, but the sheet's attachment has been moved slightly to windward of center so that it can be eased to allow some sail twist (boom moves up) without having the boom end move to leeward, thus causing the main to choke the slot. The lower battens can hook to windward slightly, but the upper battens should not. The luff tension is slack to increase camber and move it further aft. Draft in the lower mainsail is controlled with outhaul tension. The foot should be slack in light airs and tensioned in heavier winds. The jib's leech follows the mainsail's curve and a fairly uniform slot is achieved by moving the jib lead inboard, easing the sheet, and pushing the lead a bit farther forward to prevent excessive leech curvature and sail twist. The jib's stay as well as it's luff are slacked to increase draft and move the maximum camber aft. All of these adjustments create powerful sails for light airs, but it should be said that in a real drifting match, where the breeze is almost calm, the sails should be made much flatter to maximize projected area, minimize stalling and limit slatting in motorboat swells.


SAILING OFF THE WIND

When running before the wind, sails provide power through drag, and you must guard against one sail blanketing another. Blanketing occurs when the forward sail comes into the wind shadow of the after sail and is starved of non-turbulent air. This situation is caused by sailing by the lee, and the obvious solution is to head up a bit to give the forward sail clean air or, when a spinnaker is not carried , jibe over one of the sails and sail wing-and-wing.
Of course, the smaller the offending sail and the farther it is from its victim, the less the blanketing.

There are times when a headsail can be carried successfully in the lee of the mainsail, if it is used in conjunction with a poled-out jib. The sails can be arranged to minimize blanketing by encouraging the air flow from leech to luff on the windward sail to spill into the wind-starved leeward sail.












We (Richard Henderson) carry a drifter-reacher opposite a poled out genoa on downwind legs when racing in non-spinnaker events, and the combination is astonishingly effective. In fact, my crew and I are often amazed that on certain occasions we can keep up with boats carrying spinnakers. This seems to indicate that not only twin jibs can be effective but also that spinnakers are not as beneficial as many sailors think.















So, the split jib of the KD seems like a pretty good solution to sailing downwind.









1 comment:

floatingkiwi said...

I like to post feedback whenever I feel it is appropriate and this post deserves that.
I am restoring a folkboat and haven't yet decided on the rigging layout but I would like to make provision for all possible combinations and this site and its descriptions,"Kerry Dancer"(cool name), is one of the most helpful and easy to follow, I have read.Adding this to my favourites. Thankyou.
KerryEmmerson.
Kiwi in California