What sort of loads do I need to allow for on a Furling Line?

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NickHarley

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25 foot 'cruiser' - although 80's design so relatively big Genny. Have had problems in past where crew (wife) has had furling line pulled out of her hands, unfurling when trying to furl... so am thinking of replacing standard 'horned' deck-cleat with some sort of Clutch (or up-market 'clamcleat' type gear).

I realise furling lines are not as load-bearing as sheets/halyards etc., but does anyone actually know what sort of loads they have to cope with? Furling line is approx 6mm, which I'm guessing is something like a theoretical 500-900kg break load, but I suspect its thickness is mostly to do with ease of handling (I doubt the drum would take that load).

Spinlock do some nifty 'swivel' Cam cleats, but SWL is only c.140kg for this line, and even the smaller clutches 'proper' (Spinlock XAS) would appear to have c.300kg SWL.

Are these enough (with a margin of safety)? Does anyone have any general advice or recommendations on fitting this sort of solution for furling (there's a bit of an angle involved, so maybe (jamming?) turning block should be used)?

Many thanks!
Nick.
 
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If you can pull it in by hand (and if you can't there's sommat wrong) then the load is not going to be much above 30 kg or so, unless your first name is Arnie.

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Yes, but when you actually try and furl you have to take the load out of the sail.... The peak load on the line with a half furled sail to windward will be higher.
 
re: pulling it in by hand

You're right about 30kg etc. BUT - When I pull it in by hand... I've normally taken the load off the sail by releasing the sheets or luffing etc. I'm more concerned about load when the sail is fully loaded (or overloaded!)....
 
Nick... I had this situation on our boat (35') finding pulling on the furling line was getting very diffucult,esp.in any wind. Solved it by fitting a small self tailing winch aft of the main winch,on a suitable plate to provide the correct angle for the line. It makes an amazing difference,we can furl in and reef the genny easily,a bit at a time ,or let it out under complete control.I realise that you are asking about a cam cleat,but this solution is worth considering.
 
Re: re: pulling it in by hand

Same as the sheets... Maybe!? I was assuming that the furling line load was less because a) the load is lead around the forestay; & b) furling lines are always thinner than sheets!... but I guess that's what I'm asking...
 
do you not run the risk of loosing the feel for the line? Evry boat ive sailed has had a tendency to lock up on the furling drum for many reasons from time to time.... could be an expensive application of torque.
 
Slight drift but, a mate of mine lost his entire rig (with new sails) when he ran off down wind,the tired furling line broke,the whole genoa unfurled and filled with a bang,and pop went the rig over the front...
So,if you are going to resort to winching it in,may I suggest that you fit some high quality strong line at the same time,without necessarily overincreasing the ropes diameter?
 
Re: re: pulling it in by hand

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Same as the sheets... Maybe!? I was assuming that the furling line load was less because a) the load is lead around the forestay; & b) furling lines are always thinner than sheets!... but I guess that's what I'm asking...

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Load on furling line is indirect load and via a turn-drum. It is certainly nowhere near sheeting loads. If it was then you'd have furling lines of similar size to sheets.
Having difficulty furling when wind is at high strength is common and many boats would turn to wind to reduce load to be able to furl more easily. Winching is a possibilty, but then you risk overstressing that line and drum with the incredible power you can exert. Surely best is to find way to reduce load not overcome it with brute force.
 
Roughly, the load in the sheet divided by the mechanical advantage of the drum, which might be 3-5x the diameter of the partly rolled sail, depending on how much is rolled. So quite a lot when its blowing. It can also jolt if the sail flaps.
The consequences of it unrolling in F7 suggest a good margin is called for. I think there may be some words about sheet loads on the Harken site? Also the mechanical advantage of the jib winch will be a clue, A 55 winch x 50lb on the handle is about a ton on the jib sheet for a 40 footer???
Any better numbers anyone?
 
The furling line on my 31fter pulls through a cam cleat. It is hard work for SWMBO and I usually do it for speed. Line is right by the sheet winch so that can be used if it is free or line is long enough to go across cockpit (although I've never done that, come to think of it). 8mm line is plenty.
 
No You don't blindly wind it in without any regard for the forces involved. When winching in.I watch the drum to ensure it is turning freely.So far ,there has been no sign of this happening .I always turn into wind to ease off the sheets as I used to do,but the winch gives much more control of the furling. It works. PS I use good 8 mm line.
 
Re: re: pulling it in by hand

No. By the ratio of the foil diameter to the drum diameter. From memory on mine the foil is abut 25mm and the drum about 75mm so the line tension will be about a third of the sheet tension
 
6mm sounds right size for a reefing line for this size boat. Not clear why there is concern about load on the line. The only time there is load is when you are partially reefed where you need to make off securely to ensure that the sail does not unfurl. Even then the load is not that great. On my Eventide with about 160 sq ft of sail I use a normal cleat and make it off so no load comes on the line. On my Bavaria 37 with 26 sq m I have a Rutgerson jamming cleat that is just a lever against a sheave.

I guess you have around 140 sq ft which should be easy to handle manually with a good lead and a clam cleat with a fairlead should be plenty strong enough.
 
The horn cleat should be fine for the job. I suspect that you need to show wife how to use the horn cleat to advantage. That is use it to provide friction with half a turn or less of the rope pressed against the horn. Left hand holding guiding the rope against the cleat the right hand pulling in then releasing while taking up with the left hand.

I think horn cleats are vastly superior and more reliable than cam cleats or even clutch. The only advantage of clutch or cam cleat is that you can pull the rope on with a winch through the cam or clutch.
Yes you need a stout reliable rope. If you must use 6mm rope for fitting on the drum then go for a spectra or similar strong rope.

So if you can't get a horn cleat to work then you need a winch and even then a horn cleat after the winch is best cleat. olewill
 
IW395, I agree the strain on the furling line is minimal when furling but when the sail is "loaded" i.e. sheeted in, then the load on the DRUM (the other end of the foot (load on tack = load on clew)) will therefore be the same as the sheets, (I can stand on my sheets, they go bar taught in a blow). The load on the reefing line will be less than sheets according to your ideas of mechanical advantage. Try unfurling a reefed genny by releasing the furling line BEFORE unloading the sheets, (be very careful) the load is massive and the furling line is small so you cant grip it!

That said my 43ft has a 18mm sheet and a 12mm furling line through a spinlock cam cleat. Under sail the cleat is "loaded" the method of fixing the cleat to the deck is IMHO more of a concern than the type of cleat.
 
The size of the line is a function of the drum size. Going up from 6mm to 8mm and there will not be enough room on the drum to fully furl the sail.

As olewill says, surging around a horn cleat is an effective way of controlling the rate at which the line goes out when you unfurl. Reducing sail is better done with sheets eased and sail not pulling. Can't see the need for high spec lines on a cruising boat.
 
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