CUNNINGHAMS AND LINE HELD SLIDES

Aug 11, 2011
857
O'day 30 313 Georgetown MD
Looking at my mainsail recently I noticed that many slides on the sail are being held by a line on the lower section of the sail. Thinking this as jerry rigged, I purchased some extra slides and slide shackles. Took some time this weekend to review and perhaps replace when I realized it seems like this line with the slides in place is exactly how it should be. I have no experince with this set up. My immediate thoughts are that is helps to lay the sail flatter at the cunningham rings when the sail is reefed and flaked. I hope I've been able to explain the set up and can someone confirm my theory or tell me I've got it wrong and explain what its all for?
Image.jpg
 
Oct 22, 2014
20,993
CAL 35 Cruiser #21 moored EVERETT WA
Nice drawing Robert. Can you post a picture of how the lines are run? Are there holes in the sail? Are the lines only at the luff?
 
Nov 8, 2010
11,386
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
I'm assuming that the line goes slack when the luff is not pulled tight? If so that might help the lower part of the sail stay clear of the reefing cringle when reefed, which would be a plus.
 
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Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
If I understand your concept, they're called jack lines. Read about them on sailmaker's websites. They avoid having to remove the slug stop on your mast when reefing or using the cunningham.
 
Aug 11, 2011
857
O'day 30 313 Georgetown MD
I looked up Jack Lines just to be sure my concept of Jack Lines was correct and I don't believe the line that holds the slugs on the main sail to the mast is called a jack line.
My understanding a jack line runs the length of the boat either side to which you attach a tether and the other end of the tether on to your body harness, sometimes built into your life preserver. This saves your Derriere when you go overboard if you are hooked up to it. So to avoid any confusion, tonight when I get home I'm going to take a few pictures and post them to show exactly what I have.

((To explain my Van Gogh of a drawing, the large circles are the cringles, the 3 pairs of larger black dots are the collets that the line runs through. Each pair of collets has the line run through holding a slide. The small dotted line with the slides (drawn in reverse of how they mount) is the line (rope) in question. ))
 
Aug 11, 2011
857
O'day 30 313 Georgetown MD
Nice drawing Robert. Can you post a picture of how the lines are run? Are there holes in the sail? Are the lines only at the luff?
Only on the luff, only below the highest reefing cringle of which i have two for reefing and down, one at the base of the luff.
There are 3 or four pairs of collets, the line runs through the collets, between each pair, the line holds a sleeve.
 
Feb 26, 2004
22,760
Catalina 34 224 Maple Bay, BC, Canada
My understanding a jack line runs the length of the boat either side to which you attach a tether and the other end of the tether on to your body harness, sometimes built into your life preserver.
Different use of the same words.

I just did a Duckduckgo search on "jack lines on sails" and found this as the FIRST hit:

 
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May 17, 2004
5,028
Beneteau Oceanis 37 Havre de Grace
Mar 26, 2011
3,401
Corsair F-24 MK I Deale, MD
Jackline is a safety line (jackstays in the UK). Jack line (two words) can be any of a number of utility lines, including this. Like "jack of all trades."

Another purpose is to prevent pulling the slides out of the sail when and upwards angled boom is lowered during furling. If you think about it, the luff perpendicular gets longer when the boom comes down. It is NOT a jury rig.
 
Jan 7, 2011
4,726
Oday 322 East Chicago, IN
My O’Day 322 also has that setup. I don’t know the purpose, but my boat moves when I hoist the main sail, so I don’t worry about it to much.

If I have the sail raised all the way, the line is pretty tight and the sail shape is ok (for what I think is a 30-year old original main sail).

If I reef, this section of the sail is loose below the reef ring.

Greg
 
Jan 7, 2011
4,726
Oday 322 East Chicago, IN
I just watched the video about the sail for the C &C. My gate is a little high, but the slides go down past the gate cover, so I probably don’t need the jack line set up.

But like I said, when I raise the main, the boat moves...so...let’s sail.

Greg
 
Aug 11, 2011
857
O'day 30 313 Georgetown MD
Well gosh darn it, I've learnt something again. Stu is spot on. That exactly what I've got, but my sail is much dirtier (HA HA).
Thanks Stu, you really came through. Very good video. Thanks. Oh and jury or jerry.......mmm, quite interesting.
IMG_2760.JPG
 

RoyS

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Jun 3, 2012
1,739
Hunter 33 Steamboat Wharf, Hull, MA
Have that as well. Also you should use a cam cleat on the mast just below the boom to tension the jack line after raising or reefing the sail. When reefing just grab the jack line near the bottom of the reefed sail and tension while inserting into cam cleat. Simple to use and shapes the sail nicely at the bottom. Jack line end should be loosely tied at the sail tack until the halyard is tensioned and tied off. Then tension the jack line by pulling down by hand and place in the cam cleat.
 

RoyS

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Jun 3, 2012
1,739
Hunter 33 Steamboat Wharf, Hull, MA
Keeps the lower luff tight against the mast even when the slides are piled up due to reefing, but you need the cam cleat on the mast.
 
Oct 22, 2014
20,993
CAL 35 Cruiser #21 moored EVERETT WA
@RoyS it sounds like you are using the 'jack lines' as a Cunningham or downhaul to tighten the mainsail luff. From the size of the lines I see being used in the video or the picture by @twodzusfittings I would think the lines are not designed for that purpose. The 'jack lines' appear to be designed to just capture the sail slugs when the sail is dropped and the bottom slugs fall out of the mast track. The sail image shows two cringles that would be used to tighten the sail luff with a proper sized line.
Am I missing something?
 

RoyS

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Jun 3, 2012
1,739
Hunter 33 Steamboat Wharf, Hull, MA
In my case the reefed sail lower slides do not fall out of the mast slot. They do stack up at the bottom. When reefing the appropriate cringle is placed on a hook on the boom and the halyard is tightened. Lastly the jack line is pulled down and clipped into the cam cleat. This last action draws the luff snugly against the mast. Even the stacked up slides are applying this force. The downward force, applied with your fingers, is minimal and the jackline is not under much strain. I would supply a photo but I am away for a few weeks.