Jib sheeting angles

[Albert Ross]

G'day
Does anyone out there know how to work out the best sheeting angle for a storm jib .. that is, how far from the centre line the jib cars should be?
Thanks.

 

[Sheerline]

I suspect there is no "right" answer to this question.

On my 25 footer, all my headsails sheet at 11 degrees - but I race, so height is important to me in all wind conditions.

My guess is that a genuine storm jib would be happier around 15 degrees.

The strength of the deck where you're mounting the track would also be a consideration. /forums/images/graemlins/smile.gif

 

[Talbot]

The answer to your query really depends o the angle of cut of the storm jib. I suppose that you are considering an off the shelf storm jib, cause any sailmaker would be able to cut a storm jib to fit existing genoa car positions.

 

[fluffc]

I believe that Jibs should be sheeted at angle which, when drawn, would extend straight beyond a line drawn between the clew and and point half way up the luff. ?

 

[Aeolus_IV]

Yup - draw a imaginary line from the mid point of the luff through the clew of the sail, and the jib sheet should form a straight continuation of this line. This will result in a even load along the foot and leech of the sail. However, to achieve this the genoa cars will need to be moved for and aft depending on the point of sail.

Regards, Jeff.

 

[Albert Ross]

Thank you for all your help.
2 issues:
1. Vertical sheeting angle, as explained above; I think this controls the relative tensions in the foot ane the leech and therefore the amount of twist
2. Lateral sheeting angle. How much the clew is pulled inwards towards the centre line of the boat; This will control the angle of attack of the wind and therefore how high the boat tries to point .. this is the figure I'm looking for.
I would be very grateful fot any futher comment / advice.
Regards
Peter

 

[fluffc]

For lareral angle, I would just continue along the line of your existing genoa cars. I would not be tempted to sheet the sail to far in, as this may close the slot between it and the remains of the mainsail (or at least start the mainsail stalling).

 

[tugboat]

I think we need to know where is the stay you are hoisting your storm jib. If on the same forestay as you would use for your genoa, suggest your present genoa tracks will be OK if you can move the cars forward enough. This is not ideal as the effort from the sail is really too far for'd and you have lost the slot effect. If you are using an inner forestay, suggest you arrange the sheeting angle so that the storm jib is roughly parallel to a tightly sheeted genoa.

 

[Albert Ross]

Thank you.
I'm using a temporary inner forestay but this is only 20 cm aft of the genoa stay (Jeanneau 34)..... Sounds like I should be able to use the existing jib cars.

 

[LadyInBed]

I don’t understand this 11 and 15 degrees. Are we talking to the horizontal, the vertical or off the stem - stern line?

 

[William_H]

Nigel B we are talking the angle of a line from the forestay to the sheeting block made with the centre line of the boat. For a genoa this angle is often dictated by the need for the sheets to pass outside the sidestays so is often larger than would be ideal. Your storm jib could be sheeted inside the stays possibly to a pulley on the cabin top. funny on my last pleasure sail a week ago I was experimenting with a tiny jib in exactly this way. I used the existing genoa pulley on the track but then passed the jib sheet inside the stays through a pulley on the end of a rope which was tied near the mast base. This pulley (one for each side of course) provided the pull in toward the centreline and stopping chafing on the inside of the sidestays. ( there was some chafing on the cabin top grab rail) The normal sheet pulley on the track provided the correct vertical angle for the sheet to the sail. I think it does improve the pointing of the boat using the tiny jib. I imagine in a storm situation it may still be important to bhe able to point the boat and sail to windward. Of course wisdom suggests a large sheeting angle for strong winds an equivalen to letting the boom go out on the mainsail but this may compromise your pointing. You don't want to choke the slot between the jib and the main but then with a tiny jib this may not be so important. Give it all a try. In my case with a very tender trailer sailer with a large main the tiny jib ( the clew only just reaches the mast)is often used for pleasure sails in 15+ knots so it is important to have it working well. Hope this makes sense give it a try regards will

 

[Sheerline]

I reckon that if your #1 genoa sheets at about 11 degrees and the track runs forward fairly straight, you'll be sheeting the storm jib at around 20-25% at the front of that long track - which is too wide and the boat won't point. That's why most boats have more than one track, with the forward tracks moving inboard to get the angle right.

If you fly the storm sail on the inner forestay (as has been suggested) the sheeting angle will be even wider. Another effect of this will be more weather helm, because you are moving the genoa/jib back and therefore moving the centre of effort aft.

Sails aren't cheap, so a sailmaker who wants the job should be willing to explain your options and guide you before you start drilling into your deck to fit a new track.

 

[Albert Ross]

Thank you.
I think I'm looking at making it about 15 degrees, inside the shrouds, either off the cabin top, or using an extra block to the base of the mast (to get the angles right).
Happy New Year to all.
Peter