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post #1 of 9 Old 11-14-2012 Thread Starter
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Thoughts on jib sheeting inside the shrouds

My boat's shrouds lead to u-bolt type chainplates literally at the rail of the boat. The jib is sheeted to a block on the rail, then led aft to the winch. This arrangement leads to a considerable amount of chafe upwind, both on the lines and on the clew of the working jib, it makes setting up the 50% jib a real PITA and chafes the lines a lot in that case, and I get the feeling that it can't be helping my upwind performance. Oh, and adjusting the car for the conditions is very difficult, involving hanging over the rail and popping the snap shackle that holds the block on the rail.

The solution would be to run a 6' long jib track on the deck, right next to the coach roof, on both sides of the boat. It would bring the clew of the jibs inboard by about 10 inches. I would have two jib sheets per side. I would keep the jib sheets leading to the blocks on the rail for off the wind sailing, but have an additional sheet leading to the jib car which will be on that track for upwind work only. This will eliminate chafe, make sail changes so much easier, and I hope help upwind performance a little (though my shoal draft keel is my biggest limitation in this respect).

Is there any reason this is a bad idea, other than the extra lines in the cockpit?
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post #2 of 9 Old 11-14-2012
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Re: Thoughts on jib sheeting inside the shrouds

If you can physically do it (ie. your side stays actually let you) it's a very good idea and used a lot on your average racing yachts. Since you've not posted any pics of your side decks, it would help to know what sort of boat you have.

You don't need extra lines in the cockpit - it's only the track you need to install. You move your existing jib cars and sheets to the inside track whenever you intend to use it.

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post #3 of 9 Old 11-14-2012
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Re: Thoughts on jib sheeting inside the shrouds

I've been considering this idea for our Tartan 27' as well; putting an inner fair lead track next to our coach roof.
I don't think there is anything bad about this idea except perhaps slightly more complex sheeting, something else to trip on when going forward and putting holes in the deck. In theory the inner track would provide a tighter sheeting angle for the jib giving you higher pointing ability. That is the theory as I understand it.
On my boat a short track of around 2' in length would probably do the trick, while our outer tracks, mounted on the rail are about 6' long.
I owned a 19' Lightning that was rigged for racing and it had a similar arrangement with the inside the shrouds sheeting advantageous for sailing upwind and the outer (around the shrouds) sheeting for off the wind sailing. This arrangement worked great on the Lightning.

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post #4 of 9 Old 11-14-2012
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Re: Thoughts on jib sheeting inside the shrouds

It can be helpful, as you can 'close' the angle of attack of the sheeted in sail, and it will certainly be more adjustable than moving a snatch block along a perforated rail.

It will limit the headsail size, though - if you bring the clew inside the shrouds - to a sail that won't run the leach into the spreaders. However if the track is long enough a genoa could be sheeted in at a better angle as long as the camber of the sail will accomodate the spreader/shroud without excessive chafe. Another thing that will crop up that may not now is chafe along the coamings and cabinsides with the new, narrower leads to the winches.

Then there's the issue of actual gain.. the boat sorta has to be designed to work with that rig configuration and in some cases the underbody won't support your new 'pointing' ability and you'll suffer from enough leeway to wipe out the perceived improvement in 'pointing'.

But it 'looks' faster!! Worth a try if you don't mind spending a few bucks. Just be sure to properly back (and seal) the track installation.. the loads can be considerable and you don't want soggy deck core a couple of years down the road.


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post #5 of 9 Old 11-14-2012
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Re: Thoughts on jib sheeting inside the shrouds

What are your tell tails telling you?
There you will find your answer.
Hope this helps.
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post #6 of 9 Old 11-14-2012
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Re: Thoughts on jib sheeting inside the shrouds

I have the same issue. Jib on the toe rail, leaning over the lifeline on the leeward side to adjust. This is the low cost way that I've solved it.

1) A small block 8' from the bow and another right near the cockpit, both shackled to the toe rail.

2) A loop of 3/16" StaSet thru both blocks, tied to the jib sheet block in the middle.

3) Jib sheet block snap shackled around remaining loop.

4) "Line arrestor" over to prevent travel, actually only required on one line.

5) I've included a ROUGH sketch for your viewing pleasure. I'm actually an architectural designer and work in 3D modeling almost exclusively but I had 23.14 seconds to pound this out before the boss came by so . . .deal with it!

I used a clothes line tightener this year, as a proof of concept, just to see how functional it would be. It works SLICK! Loosen the arrestor (from the safety of the cockpit) and pull a line to adjust the block location. Let the arrestor tighten again. DONE! This winter, I have plans to build two blocks from aluminum and nylon with a cam latch for tightening. The jib block will run along the lower StaSet via another small block.

This is essentially a modified Barber hauler. I tried a standard Barber hauler but it didn't give me as much control as I would like.

So, for those who might say "3/16" StaSet?!?!?! Are ya DAFT laddie?" It has a tensile strength around 1900 lbs X 4. I'm not worried. Others might question why I wouldn't just get a track and bolt it on. Well, shallow pockets for one. Another is the size of my boat really insists that I keep the side decks as clear as I can.

Again, it works slicker 'n whale snot!
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post #7 of 9 Old 11-14-2012
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Re: Thoughts on jib sheeting inside the shrouds

You can sheet your jib to the base of the mast if you like, but it may not help you point any better or go any faster. Closing off the slot between the jib and main by tightening your sheeting angle may create so much backwind in the main that it is counterproductive. You may point higher, but if it cuts your speed by 3 knots and increases leeway, it's not really helpful. Having an existing setup led to the rail lends to a guess that the sails involved here are not less than 2 years old, and may perhaps be somewhat blown out. At best they were cut for a more modest angle of attack than the one you're contemplating, so may not perform well at all if sheeted in at a tighter angle. The best way to find out before going crazy buying hardware and drilling holes, is to try what Don suggests first. Rig up a barber-hauler of some sort that will lead the jibsheets inboard: Attatch a snatch block to a line and cleat it somewhere on the cabintop so that a jibsheet running through the block is inside of the shrouds. Then lead the sheet back to the winch so it avoids chafing points, of course. You may need to use a hefty snatch block - you don't say how big your boat is. Do the same P & S, and see what it does. Does the jib shiver at the leech while the luff is full? The draft of the sail may have blown aft, calling for a new or recut sail to work with the new angle of attack. When you sheet in the jib does half the main start to backwind? You've closed off the slot too much, which means you're putting on the brakes, not the accelerator: ease off the barber hauler to open up the slot. If you're lucky, the tighter angle will enable you to avoid some of the chafe you mentioned and point higher without going too much slower. Try a bunch of different barber-hauler positions to see what works best. It could be that a single padeye on each side could work the changes you seek - much cheaper than a track with a car, and a lot easier to install. You could also find, like Don, that the barber hauler works well enough to not need anything more than that. Have fun playing!

Last edited by paulk; 11-14-2012 at 09:46 PM.
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post #8 of 9 Old 11-15-2012
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Re: Thoughts on jib sheeting inside the shrouds

If you are like me, you will not be able to use a 150 on the inner track, at best maybe a 110% to jib fortriangle! I have pics of what I did to my outside tracks HERE, in the article it shows where my inner tracks are that were added after the fact. Some boats even have both of the tracks as I have from the get go!


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post #9 of 9 Old 11-15-2012
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Re: Thoughts on jib sheeting inside the shrouds

Sheeting inside the shrouds 'may' be a good idea for better upwind performance.

Certainly the problem of hanging over the rail and adjusting fairlead cars is easily and economically solved by changing to something like the Garhauer EZ glide adjustable (from the cockpit) genoa car system - Garhauer Marine Hardware -5217233

However bear in mind that several things may adversely occur at the same time when sheeting in overly close:
1. reduction in aerodynamics due to the jib leech operating at 'too close' to the point of maximum draft in the main - and the 'bootstrapping' which enhances both jib AND mainsail aero-performance rapidly falls off.
1a. possibly needing a new / flatter mainsail as in 1 above (so-called backwinding) Typically to bring the jib clew within the 10 tack angle you need 'racing cut' sails - Not a forgiving 'rounded luff' cruising cut sail for the unprecise helmsman; rather, a 'flattish' shape at the luff sections instead of 'rounded' and a 'precise' helmsman.
2. Jib LP interfering with the spreaders, as Faster already stated.

Normally on most boats the jib clew position for 'best upwind' angle of attack will best optimize at a line at 10 offset eminating from the tack of the jib ... running back and across the 'rail' at that offset angle; 12 on boat with 'cruising cut' sails. Any (attack) angle much less than 10 on non-high-end designed boat is usually 'pointless'. Cruising boats usually best optimize between 10-12 jib attack angle, the 12 line favored to compensate for the use of 'forgiving to the helmsman' / unprecise sails.

Before you fully commit to an inner rail, Id recommend that you 'experiment' by using a 'barber hauler' - a line that is lead perpendicularly along the horizon from near amidships to the jib clew and simply 'tied' additionally to the clew ring.
Then do some data collection of various attack angles vs. boat speed with varying 'in' settings on the barber hauler .. or better yet, watch your VMG to a very far waypoint. The boat's VMG will optimize at the 'best' attack angle and important 'slot open distance' for the exact wind and wave conditions at the time.

You will probably have to slightly loosen the main halyard to flatten the 'luff entry' shape a wee bit ... but that creates a more draft aft mainsail shape, so dont 'overdo'. If your mainsail is cut for 'cruising' - a 'rounded' rather than flat luff entry shape you will most probably experience a LOT of so-called backwinding when you do barber haul .... just ignore the backwind, especially if the VMG numbers are getting 'better' as you pull in.

How to barber haul: Set up the boat with the FULL set of tell tales (including steering tales)... once the sail shape is correct and the tales are flying perfect, ignore them except the row of 'steering tales' or 'gentry tufts' about 'head high' and emanating from the jib luff back for a few feet. Begin to pull in the barber hauler while recording and noting VMG (this takes a while and doesnt happen instantly as it takes time for the aerodynamic flow to 'settle in and adjust itself' to changing sail interaction of 'the slot'. The optimum barber haul 'in' setting for the days wind and wave conditions will where the boat 'maximizes' its VMG. You will need to do a lot of data recording, etc. to make this 'work'.
Then once youve determined the best barber haul 'in' setting vs. various wind and wave conditions, then simply install the inside track based on these optimum recorded data numbers.

When questioning so-called backwinding, especially in lighter wind condition when the vectorial sum of the attached flow of airstreams on the windward side of the sail is actually and visibly seen in the tell tales as 'going forward' ... you have to make the 'guess' if what youre seeing is 'actual' aerodynamic flow .... or that youve simply 'closed the slot' to where the 'aerodynamics' are simply decreasing. The way around all this when barber hauling is forget the tell tales (but not the 'steering tell tales) and simply look at the speedo or the VMG and no matter what you 'think' is happening as 'backwinding'.

To help understand what is going on ... the aerodynamic flow CIRCULATES mathematically 'around' a sail/sails (most 'sailing books are simply 'wrong'). The best explanation for the non-technical person in: The Origins of Lift .... and shoots to hell the erroneous concept of 'backwinding', etc. but yet what looks like backwinding will develop when the jib gets too close to the mainsail when barber hauling, etc. Use your speedo or VMG when barber hauling or using an 'inside track' and simply 'ignore' any minor 'backwinding'.

Hope this helps.

Last edited by RichH; 11-15-2012 at 01:42 AM.
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