Latest News: Forums Technical Jib Furling Systems – an enquiry!

  • This topic is empty.
Viewing 15 posts - 16 through 30 (of 39 total)
  • AUTHOR
    POSTS
  • #10298
    Swiebertje
    Participant

    Hmm, google translate. Maybe that’s one too many?

    #10311
    Anonymous
    Inactive

    Using a narrow diameter flexible plastic pipe split along its length I converted my genoa furling system to reefing for a few pounds.The only difficulty is cutting in a straight line down the length of the tube. Once done slide the tube over the luff wire and stitch in place.

    Granted you will not get the efficency of a professional system but for day sailing, single handed or with children, the difference in performance is unlikely to be significant.

    I know of two or three other members who have done the same and no one has experienced any problem with the sail unfurling in strong winds.

    #10339
    revoli
    Member

    My wayfarer came with a furler. I have always used this for reefing the genoa and have not yet managed to make the genoa unfurl at the top even during some recent very strong winds. My Genoa does appear to be very rigid along the luff (it’s a hood sail) so not sure if this has something to do with it but at the moment I cannot see a need for me to upgrade this (I have yet to hit a storm at sea though) I sail single handed or with young children and cannot praise the genoa reefed on it’s furler and the mainsail reefing lines I installed enough. That and the masthead bouyancy (currently plastic bottles) I think are essentials if single handed or with kids.

    #10589
    Anonymous
    Inactive

    We bought a Selden furling drum and swivel which while functional for the purposes of mooring to quickly furl the headsail or to stop that annoying and sail wrecking flogging while setting the boat up for the day. We planned to add a flexible spar to turn it into a reefing system to add the flexibility of variable sail size but at the moment that project is on hold as we experienced problems with the Selden system particularly in high winds.

    In very breezy conditions, the extra tight luff wire inevitable causes even a well tensioned forestay to sag significantly and always gets caught in the sail when furling. Under high loads the furler and more significantly the top swivel is no longer smooth to rotate ( in fact the top swivel quite often wont rotate under high load ) so its all but impossible to get the sail to furl evenly and one ends up with a baggy mess flogging in the wind. In addition the forestay spacer which forms part of the Selden top swivel is a short steel wire post that wraps around the forestay and screws into the swivel . This is far too short to provide sufficient spacing and of insufficient strength to avoid bending and so eventually snaps.

    All that said we have had two seasons with the Selden furling system and in light to moderate winds is brilliant and saves a lot of faffing about rigging and de-rigging. However this year I bit the bullet and bought the massively more expensive Harken furling drum and high-load swivel, I have yet to sail it in sufficient breeze to test it thoroughly as the boat is currently undergoing its winter refit but the smoothness of these new fittings at the highest tensions I dare put the rig is awesome and induced virtually no twist on the halyard above the swivel whatsoever. I am convinced this will mean the sail will furl smoothly in any amount of breeze.

    So to the remaining issue of the sagging forestay, as I am convinced removing it would be a bad idea, I am thinking about a secondary tensioning system that is either automatic and consist of some shockcord attached between the mast and the forstay or a tensioning line led back to the cockpit. Either of these would attached to the forestay roughly level with the top swivel and the positioning on the mast would be such that it gently pulls the forstay away from the luff and prevents sagging. I have done a rough sketch and invite riducle / serious comments from other readers: [attachment=0:1u00c9h0]forestay tensioner.JPG[/attachment:1u00c9h0]

    #10590
    admin
    Member

    Hello, I too bought a Selden furling drum and top swivel; the Harken High Load one is three times the price of the Selden one so I am sure it is a common decision.

    Initially I had the same problem, that the forestay was getting rolled into the sail. I tried unclipping the forestay and securing it to an eye I screwed onto the deck about 100mm away from the bow (right on the edge) through which I have led the furling line, but it still got rolled in. I too considered removing the forestay completely or replacing it with a rope that I could detach and bring back to the mast once the genoa is up and tensioned, Laser 2000-style (I am still thinking about that, there is another thread on this topic).

    In the end I had the forestay shortened enough to allow room for a lanyard of 3mm Dayneema that I tighten once the genoa halyard is tensioned. By grinding up the lanyard tight, I find that the wire loopy hold-off thingy on the top swivel does keep the forestay out of the sail, but if I forget to slacken the lanyard off in the right sequence when I take the tension off the halyard, the half-hitches I use to tie off the lanyard almost weld themselves into the Dayneema; I had to resort to cutting the lanyard on one occasion. So it’s not perfect but I hope to work on ways to make it better once the ice on the lake thaws.

    Removing the forestay would make bridge-shooting much easier, others have said I should keep the forestay as a safety stand-by in case something breaks. I don’t have stand-by shrouds.

    I wonder what the statistics are of a furling/reefing drum or top swivel failing? Has anyone had a forestay malfunction that could/did result in the mast coming down? What was the nature of the fault?

    #10591
    Anonymous
    Inactive

    I dont know the stats but wouldnt want to become one 😛

    I don't have stand-by shrouds.

    Thats a very good point, perhaps I am guilty of not applying the simplest solution and should just clip the forestay to the mast once the foresail is up, I’ll have to give it some more thought.

    To solve the bridge shooting issue I too shortened the forestay and the bottom part is replaced with dyneema line which goes though a couple of pulleys and back to the cockpit along the foredeck to a cleat. This system enables the mast to be lowered and raised single handed if need be and could already be used to tighten the forestay while underway as you suggest but as you say it goes horribly tight if the jib tension is released before the forestay which is why I thought a separate system designed just to take the last few inches of slack out of the forestay without needing to overtighten it might solve the problem.

    By using a shockcord elastic either at the top as shown in the original picture ( probably not the best location as it will rot quickly from UV exposure but would be the easiest to implement ) or by feeding the tensioner down to the cockpit with some 3mm line and installing the elastic inside the cockpit mounted on the centerboard casing (a similar arrangement to that used on the spinnaker uphaul) – see sketch. The tensioner line would then never be overly tight even if the jib is released first and adjustment could be made by appropriate positioning of the stopper. There is no need to release the tensioner to lower the mast for bridge shooting only if you wanted to remove it from the boat it completely.
    [attachment=0:6sw182nf]forestay tensioner detail.JPG[/attachment:6sw182nf]

    #10592
    Colin Parkstone
    Participant

    The wire that makes up a std forestay is 2.5mm 1×19 with often a weak rope tail, the wire for a halyard is 3mm 7×19 which is stronger by far than the forestay.
    What do want the forestay for? To hold the mast up on land. Well put it back to the bow when you need it!
    Is it for holding the mast up if the halyard snaps in a strong wind!
    If the halyard snaps the forestay will not hold the mast up in the winds that the halyard is likely to snap!!
    Why not have a much stronger halyard, say 4mm 7×19 ss.
    If you still want a forestay as well, move it out the way when sailing!
    Fireballs use a stuff luff for jibs, the luff pocket has no luff wire in it as its the forestay that goes up the pocket and the sail is shackled off at the head and the tack is adjustable.
    Any help?
    Halyards often snap because they are old, not looked after or miss used in some way!! Service it often and i am sure your have more faith in it when you have kept an eye on its condition.
    CP

    #10595
    Anonymous
    Inactive

    The relatively small diameter change as suggested by Colin may well do the trick and it could be argued this would make the forestay superfluous by introducing a much stronger halyard wire component.

    Although not discussing small ropes http://www.bridon.com/x/downloads/steel_technical.pdf is a guide to steel rope engineering and the principles apply to smaller diameters too. A brief glance shows this to be a much more technical subject than it may first appear – selection of correct diameter and weave type and related strength of the resulting system is not quite as straightforward as bigger=stronger. Other factors need to be considered including the minimum bend radii, handling stiffness, amount and angle of bends, torsional loads and terminating/crimping system etc.

    Given the amount of bending that the halyard takes through the mast sheave it may introduce other subtle issues such as bending fatigue or incorrectly sized sheave beds that introduce exessive wear points on the rope depending on the parts and their exist wear/corrosion as found on individual boats. There is a larger number of components that ‘could’ fail in the halyard rigging versus the simple point-to-point nature of the forestay. In short there are other aspects other than the diameter of the wire rope that might increase the risk of a failure.

    Ive personally never experienced a broken jib halyard, not to say that I wont in the future, so perhaps it could be argued there is reduced risk by not increasing the rope diameter as the other components remain within their normal working tollerances. I have however experienced a mainsail halyard cleat coming away form the mast because of electrolyte corrosion between the steel rivets and the aluminum mast.

    This clearly becomes quite a complex engineering/math problem to provide a quantitive answer that is beyond me.

    I guess the bottom line here is ‘ what’s the worst that could happen with no forestay while sustaining a broken halyard?’ – in the case of the mainsail halyard cleat failure it meant the mainsail dropped and we de-powered, I simply re-launched the sail and used an unused mast cleat to get back underway. However the jib halyard or any component in the halyard system failing could result in the whole mast becoming dangerously unstable ( as too could the failure of a shroud ) which is entirely a different thing.

    #10596
    admin
    Member

    I think it should be clear if the stainless steel wire is at risk of breakage, fish-hooks and rust staining should give you a fair warning. The crimps on each end of the wire could fail but what I would like to know is whether anyone has had a furler or top swivel fail (break)? Increasing the wire guage may not be the most important issue if the bearings in the drum give way under load.

    Interestingly I could not find the breaking strain of the Selden drum from a cursory Google search, I think I kept the paperwork that came with it, I wonder how it compares with the tension needed in the genoa halyard to generate the correct shroud tension…

    #10597
    Anonymous
    Inactive

    The Furlex20s datasheet http://www.seldenmast.com/search.cfm?downloadmanual=7142685&filename=595%2D496%2DE%2Epdf indicates 500kg max working load. While it doesnt quote it, breaking loads are typically somewhere around 50% higher for most equipment.

    The Harken 434 is rated at 227kg and the high load 435 is rated at 431kg http://pdf.nauticexpo.com/pdf/harken/harken-catalogue-2011/21575-23956-_147.html so I would suggested the published Fulex working load figures are somewhat generous to say the least ! To my mind ‘working’ implies you can still turn it !

    While checking the Harken site they are now offering a hoistable swivel system which suggest its possible to tension the luff separately from the forestay – perhaps this is the answer to our prayers !

    … er hum except its ludicrously expensive:
    harken 464 hoistable swivel £190.59 purple marine
    harken 479 4mm tack adaptor tang 108.18 purple marine

    #10598
    Swiebertje
    Participant

    The solution is staring you in the face: Look again at the Seldén file you posted. What do you think is the function of the 97mm pin on the top swivel? Hint: An old CD works just as well. That and a short length of bungee cord at the bow is all you need. There is no need to modify the mast at all. And the simpler the system is, the more reliable it is.

    BTW there is a reason the Harken High load is expensive. Together with the Bartels furler it is the only one I know that furls under high load. All the cheaper ones require you to take the tension off before furling the Genoa. In condition where I need to reef the last thing I need is a complicated reefing exercise.

    Visit the cruising conference coming April and see how others have done it.

    #10601
    admin
    Member

    Yes a CD could be used but it must be held perpendicular to the halyard to do its job so a simple CD would need something to fix it properly. The amount of spacing and the tension required (in my experience) would require a robust mounting to stop it twisting away and breaking.

    I see that RWO make one that fits on their top swivel http://www.tridentuk.com/sailing/produc … R2070.html.

    Dean I suggest the difficulty with your bungy rope idea might be making an attachment to a featureless length of fore-stay and the amount of force needed to be applied at an un-oppertune angle needed to pull it out of the way. I like your thinking however.

    A word in defence of the Selden furler and top-swivel; I have tensioned my rig to suit “heavy weather” in the Wayfarer Book which means about 130kg in the shrouds, so I guess something similar, possibly more in the genoa halyard and I have had no problem with rolling the sail away with the system under load. I have not added any extra lubrication, it just works. I don’t doubt that the Harken High-Load kit is superior engineering (most of my blocks are Harken) but the Selden kit seems to do the job.

    My question remains unanswered, who has had a furler or forestay fail? Is there a strong case, based on experience for keeping a wire forestay in place once the genoa/ jib halyard is tensioned?

    #10602
    Anonymous
    Inactive

    At the moment I have installed a Plastimo Yacht halyard diverter as the RWO one doesnt fit the Harken swivel, this is very well made and definitely not going to break but does ‘look’ a little on the heavy side however the additional mass should be of advantage to prevent any remaining halyard twist while furling.

    Hopefully this system will mean the tensioner wont be needed at all but if not, Mike, you’re right the attachment to the forestay will be a bit awkward, I was thinking of a soft wire loop swaged onto the forestay. Its true too that the angle is far from perfect and might require a sizeable force, possibly this is beyond the capability of even a thick/multiple bungy without installing a cascade sheave or two to give it additional leverage, some experimentation might be required.

    #10603
    Swiebertje
    Participant

    @Mike Summers wrote:

    I see that RWO make one that fits on their top swivel http://www.tridentuk.com/sailing/produc … R2070.html.

    On my old boat I had one of those wheels above the top swivel, intended to protect a Genoa from chaffing against the spreaders on a big yacht. It is a two part plastic wheel that slides together around a wire and does a good job of pushing the stay forward on a Wayfarer too.

    #10604
    Anonymous
    Inactive

    I used one of those last season as a diverter and indeed still have them above the shrouds for their original purpose and look a while lot nicer than wrapping the ends of the spreaders with tape. The diverter I was referring to is this one : http://www.bosunslockerchandlery.co.uk/3678/Plastimo-Halyard-Diverter-Wheel.html as its a bit bigger, much tougher and designed for the task so holds its self perpendicular much better and on the Wayfarer doesn’t look out of proportion once the sail is up.

Viewing 15 posts - 16 through 30 (of 39 total)
  • You must be logged in to reply to this topic.