Help! Roller Furling Line not Man Enough?

Boathook said:
What would the relationship be between the sheet and furling line force ?
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Could there be more that 1 ton in the furling line.

For a 36’ MAB, masthead rig, in 20kts, the sail has around 200 kg of force applied to the sheet. I just selected a yacht from SailboatData.Com. There can’t be more than that in the furling line if say there was one roll in the genoa and the furling line loaded up. If the OP uses the actual area for a furling sail and the wind figures it may give an idea of the loads. If the system is jamming and winching snaps the line, obviously the sheet load comparison is pointless.

I sail a 41’ boat with a Harken furling system and 8mm line and I can always reef by hand, and when partially reefed in 30 kts of wind, close hauled, reefing line is very tight, it doesn’t break. The sail needs to be flogging in these conditions to reef further and while it can be hard to haul on the line, it still reefs by hand.

As for actual relationship between sail force and fuller, line force, I don’t know. From what I can see from internet searches, that is not available.
 
I need to use winches on the sheets, but can generally reef without needing a winch. So on the whole, the strain on the reefing line must be less than that on sheets.

I'd echo those who say to look for whatever is damaging the line; 8mm line reefing line should be nowhere near it's breaking strain

My reefing line has a splice in it (I underestimated the length required!) and even that doesn't weaken it enough to come near breaking.
 
I've never had to resort to using a winch to furl my large (40m²+) masthead genoa. 47ft boat.
Ok I luff up when furling but, still, I really don't think the loads are anywhere close to one ton.
 
AntarcticPilot said:
I need to use winches on the sheets, but can generally reef without needing a winch. So on the whole, the strain on the reefing line must be less than that on sheets.

I'd echo those who say to look for whatever is damaging the line; 8mm line reefing line should be nowhere near it's breaking strain

My reefing line has a splice in it (I underestimated the length required!) and even that doesn't weaken it enough to come near breaking.
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The reefing line load is highest when you're not furling (unless you do it with the sail full of wind), the sheet loads are highest when winching (includes friction and wind load). I can stand on my genoa sheets when taut, the furling line is tight but nothing like the sheet loads.

Failure means chafe or damage.
 
Very odd.
If all else fails I’d suggest asking someone (another yachtie with experience) to look at your set-up and see if they can diagnose where the rope damage is happening. Presumably you still have all of the failed furling lines, old and new.
 
AntarcticPilot said:
I need to use winches on the sheets, but can generally reef without needing a winch. So on the whole, the strain on the reefing line must be less than that on sheets.

I'd echo those who say to look for whatever is damaging the line; 8mm line reefing line should be nowhere near it's breaking strain

My reefing line has a splice in it (I underestimated the length required!) and even that doesn't weaken it enough to come near breaking.
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But the strongest force on the reefing line is not when actually reefing (assume the sail is eased to do this) but when reefed - and the reefing line is all that is resisting the tension of the sheet winch pulling very hard in the other direction.
Still sounds like there must be a sharp edge cutting the reefing line - but we use cruising dyneema for the reef line with s dyneema core to give strength.
 
jwilson said:
I only replaced original from 2005 8mm polyester furling line two years ago as it was not looking very smart. Suspect your line was not polyester, and had UV damage as well as possibly something chafing it somewhere. If you didn't buy the line yourself it could be cheap polypropylene.
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That's what happens when you buy your rope from Aldi
 
Do you still have the remains of the two broken lines? If so, did they both break at the same point? And what does the break look like? Is there a length of worn or abraded line either side of the break? This is nothing to do with the strength of the line, it’s all about identifying the cause of the physical damage
 
jaminb said:
It furls really easy, the line snapped/rubbed through whilst sailing with 2/3 genoa locked out. I have now replaced with 8mm, freed off the front sheave and replaced the roller which had a big groove in it so clearly not running smoothly. It was also very stiff in the ball joint for up and down movement. Will have to monitor it more closely. I was watching my temporary repair (outside of the sheaves) yesterday and there was no sawing movement in the furling line so I am surprised it would rub through after one sail.

Could there be more than 1ton load on the furling line? (37ft AWB)

thanks for your help everyone
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Think on this ....

You can be sailing along ... and without easing off too much sheet on genny - you can still use furling line to reduce sail .....

Does that sound like 1T load ?

If you are breaking a 6mm Marlow - something is wrong ...

Think of the number of boats where they remove the centre core of furling line - to allow it to sit better on the drum ....

I have 8mm on my 38 racer ... but its definitely more than enough for the job .. I could easily go down to 6mm.
 
Refueler said:
Think on this ....

You can be sailing along ... and without easing off too much sheet on genny - you can still use furling line to reduce sail .....

Does that sound like 1T load ?

If you are breaking a 6mm Marlow - something is wrong ...

Think of the number of boats where they remove the centre core of furling line - to allow it to sit better on the drum ....

I have 8mm on my 38 racer ... but its definitely more than enough for the job .. I could easily go down to 6mm.
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Mines 8mm with the core removed for the first 7m. Not a problem with nearly 23 square meter sail area.
 
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