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Old 26-05-2023, 09:59   #1
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sail systems: out-mast furling


I'm aware of mainsail furling systems such as mast-furling and boom furling.
Somewhere I've encountered a different system, which is like out-mast furling. Basically it's a rod furling system, mounted very close to the mast on the boom.
The advantage of this system are:
- easy access
- cheap for refit, rather then changing the mast
- less chance of the sail getting stuck in the furling system

Anyways, thoughts on this pls? Does this system have a name?
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Old 28-05-2023, 13:24   #2
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Re: sail systems: out-mast furling

Initially, a few innovators attempted to retrofit older rigs with external, behind-the-mast roller-furling systems. In essence, these units were akin to a roller-furling headstay stretched between a beefed-up masthead fitting and the gooseneck. Unfortunately, as the tension between the masthead and gooseneck increased, the spar tended to bow and the luff of the mainsail curved to leeward. This made reefing and furling difficult, and placed excess stress on the spar itself.

Seldén and Schaefer solved the problem by adding evenly spaced track connections that linked the mainsail furler to the mast track. Today, Facnor also offers a refined version of this concept for those interested in converting a standard spar into one that hosts a roller-furling mainsail.
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Old 28-05-2023, 13:43   #3
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Re: sail systems: out-mast furling

found some answers here:
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Old 28-05-2023, 15:03   #4
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Re: sail systems: out-mast furling

I would run away - if you like sailing.

My mum put one on her cat back in the 80s and it was awful. It was mounted on a crane behind the mast. If you tightened it up (and you had to to get it to stay sort of straight) then it put a prebend in the mast. Still the luff sagged to leeward. Along with the hollow leech, because of the battenless leech, and incredible drag of the mast and furler, the sail was dreadfully inefficient upwind. I hated sailing with it.

Then there is the engineering aspect. Strangely enough a mainsail actually helps support a mast. The mast is often slightly prebent forwards, away from the sail. When jumping over waves, the main assists the rig in preventing the mast from pumping. People learnt this in the 80s and 90s when the masts of racing yachts fell down upwind when under storm jib only with the mast not constrained by the main. Also the induced prebend of the crane is caused by the compression located 150mm or so aft of the back of the mast, you want all the loads to be near the neutral axis of the mast - not way aft of it.

My mum's mast fell down when going upwind. The mast pumped around and then fell down off Sydney Heads - nothing too nasty, just lumpy. Lawyers at 10 paces and then everyone got cranky. Needless to say she got a normal main with the next mast and the boat sailed much better (she could use full battens and also got a more effecient planform) and the mast never fell down again.

You couldn't give me one for free - a truly awful bit of kit for someone who loves to sail upwind. Hell for me would be me sailing a yacht with immersed transoms, weed on the bum, a big 3 blade propeller and behind the mast furling.

Great on a powerboat pretending to be a sailboat though.


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Old 29-05-2023, 08:27   #5
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Re: sail systems: out-mast furling

anyone have positive experience with installations like this?
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furling, mast, sail

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