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Old 31-10-2017, 15:12   #16
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Re: Sheeting Angle, CCA design.

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Originally Posted by rgleason View Post
The points about pointing in heavy winds and seas are good, but it would be nice to know for sure that I should be sheeting inboard of the cap shroud, but not inboard of the lower forestay, as that would set the max size of the working jib.
It doesn't work like that in heavy winds because the winds are usually from a passing front and those winds usually move back and forth so you have constant headers and lifts......

Do you plan to be steering for the best possible VMG in heavy wind conditions the entire time those winds are present?

It's not an exact science................

Racing in these conditions teaches you a lot especially since you have to race with the boat's original set of sails

On boats like ours, those minimal changes mentioned above don't mean much especially in big wind

This is why one design racing is so important when learning to sail. Picture yourself racing 20 other Bristol 32's and all of you coming of the line at the start......while not going over the line too early (OCS)

The best ideas sometimes put you at the back of the pack while others are simply adjusting sail and steering through gusts they see coming
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Old 01-11-2017, 07:16   #17
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Re: Sheeting Angle, CCA design.

Suijin, yes, the solent is aft of the RF, as shown on the pdfs.

Also I just checked my older drawings, and yes the old North 140% (354 sf) would sheet to 10.5 degrees, (I loved that sail, and the 95% too) in plan, measuring the line from the clew to the tack, and the angle to the centerline. I usually trimmed the leech away from the spreader by about 2-3" however. The new Hood 135% (328sf) obviously does not sheet to 10.5 degrees and is perhaps 11-11.5 degrees. It is however more forgiving on the higher end of the wind range because of the area, the shorter luff to fit on the solent, and the lower center of effort.

When the jib is rigged to the solent, I am inclined towards a sheeting angle of 12-13 degrees for the jib, due power needed for heavier winds and seas (as pointed out). At 13 degrees sheeting angle, the jib would sheet inside only the cap shroud and be about 85%LP which is closer to the 90%-95% LP that I've found is useful for spring & fall.

Then in the spring-fall when I normally use the smaller jib rigged on the forward roller furler it might even sheet to a 11-12 degrees because the clew will probably clear the lower forestay. I think using a centerline barberhauler and releading the jib sheets from the railing track (adjusting the cars) will work for upwind sailing. The centerline barberhauler will require some higher forces to sheet the jib in.

However I hope that hoisting the bagged 85% (205sf) jib on the solent as wind increases, and bagging it as the wind lessens, it proves to be manageable. I think I may ask for two jiffy reefs, even though Jim Cate found them useless. I think this jib would qualify for a ISAF heavy weather jib, but it is probably too big and UK says it needs to be low stretch material and have battens. I am thinking I'd rather have no battens or just short vertical (for RF) to make it easier to bag the sail.

As you've suggested, I'll be asking the sailmaker about all this, but this has helped me think about the jib's use in practice and to establish what size jib and sheeting angles are likely to be appropriate.

I'll report back later. Thank you all for your help thinking about this.
PS: If you have further thoughts on this, I'd love to read them.
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Old 01-11-2017, 16:53   #18
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Re: Sheeting Angle, CCA design.

I'd forgotten about Joe Copper's article "Convert Your Sloop to a Double-Headsail Rig"

Attached is a photo of our sliding tack which tightens the solent with a 4 part pulley, its effective but it has developed a bit of a hard spot, and I think the bearings are not hard enough, because it tightens with light loads on the jib, but as the wind gets greater the car bottoms out and is harder to move. I'd like to find harder ball bearings, or maybe just replace them again or perhaps convert the track and slider to just sheet teflon surfaces.
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Old 16-01-2021, 15:56   #19
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Re: Sheeting Angle, CCA design.

I think 12-13 degrees is a reasonable sheeting angle to aim for, dependent on sea state. Smaller jibs around 90-100% when sheeted outboard, are generally at 16 degrees sheeting angle. They can be cut very high to allow a better sheeting angle.

Attached are jib plans/sections/elevations for:
  1. 85% Jib shown mounted on the solent 1' back from the roller furler. This is cut high so that it can be set between the cap and lower-fore shrouds at 12-13 degrees. (If cut lower, 12 degrees would not be possible)
  2. 78% Jib shown mounted on the solent 1' back from the roller furler. This is cut low so that it can be set inside the lower-fore at 12 degrees. (If cut lower the sheeting angle could be bigger.)
Both jibs can reside on the roller furler (during spring and fall) with no sheeting angle issues.

Using a sheet load tool, the head sails are good in these ranges (including 2 10% reefs)
  • 135% Genoa 14.7-19.1 knots (new)
  • 90% Jib 12.9-20.2 knots (old)
  • 85% Jib 18.5-23 knots (proposed) (205sf)
  • 78% Jib 19.3-24.1 knots (proposed) (189sf)
I realize that sheeting inboard anywhere will lead to more work and I need to add some jib lead adjusters that are easy to deploy and are flexible. See the attached Lead-Adjustment-2021-1-6.pdf

I wonder if the 3/16" line will be too small for our hands, and if I should drop the 3:1 Block and tackle below the Cam cleat. Perhaps I should be using 5/16" dyneema through out instead of 3/8"?

Also see Soft Solent with 80-75% Jib and Inboard Sheeting

Advice-Suggestions (appreciated)
------------------------------

Seabreeze: [Don't change sails, rake aft further to sail upwind better]

Suijin: I personally think the 90% will be the most versatile sail. You could furl it to 80-70% and not loose as much shape and performance as with your 135, and it will only really be an issue if you're close hauled.
...The 110 is on a furler and the staysail is hanked on a detachable inner forestay (which I rarely detach...I just furl and unfurl to tack, except going up a smaller body of water). Staysail goes up when working to windward, almost always.

Kestrahl: 10 degree's - forget about it for this boat, you will sit there pointing high but going nowhere. Even on my Davidson cruiser/racer with fairly good foils for its age the No3 is at 13 degree's.

DonCl: In my ol CCA boat there is more con than pro to trying to increase the sheeting angle. And btw the beam is already pretty narrow. Nah I’d just be sliding sideways more than foreways, we just don’t have the speed andor acceleration to make it make sense. I love my old boat, but it’s not going to point much higher than I got.

Jim Cate: "I would never rely upon a reefing jib or staysail for heavy weather sailing."
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Old 17-01-2021, 05:26   #20
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Re: Sheeting Angle, CCA design.

Actually, the closest sheeting angle is 14.5 degrees, for the jib outboard of the stays. That can be improved somewhat by cutting the jib higjer.
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