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Advice on setting up an Fx4500 top-down furler on the end of a 2 meter Prod


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We are setting up a new FX4500 furler with the Fast Thimble/swivel. We are committed to using a furler drum retrieval line since going out to the end of the 2+ meter prod to unhook things just is not in the cards anymore for us. I have had conflicting advice on this with regards to setting up the retrieval system. Seems that there are two schools of thought

1) Set it up on a single line thru a pully or low friction ring, This is easiest but some say that the furler drum will want to twist that single point supported line and this results in the drum twisting with the result being that the continuous furling line may get wrapped around, and the whole thing jambs. (The first picture is the end of our prod - it's folded back along side the main hull here - this shows the tang that we would lash a low friction ring to in this scenario)

2) Or.... Set it up such that the retrieval line is lead thru two points of support out at the end of the prod. This resists the twisting mentioned above and prevents the drum from rotating and wrapping the retrieval line (The second picture that I have posted is an example of this on our prod with the old FX2500 furler on the screecher. As an aside...We have experienced allot of chafe issues at the shackle attached to the base of the furler, even thru a dyneema chafe sleeve in just hours of off-shore work.

If anyone here is using a drum tack retrieval system, please weight in on is topic and help me out,  Thanks!

 

Prod Perspective.jpgThanks!

IMG_4492.jpg

Edited by 2flit
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1 hour ago, Gappy said:

You need to use the proper 2:1 shackle for the bottom on the furler to negate Chafee.

If you are at the end of a prod a 2:1 is by far the best option to stop trust.

 

Have you experienced twist as an issue? Twist  that goes so far as to where the furler line gets carried around the body of the furling drum as the drum rotates. There appear to be boats that have spinnaker top down furlers on a single line? Thanks for the advice on the Slid Sheave part # SSH4500, looks far better than that shackle!

Facnor SSH4500 Slid Sheave.png

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7 hours ago, 2flit said:

Have you experienced twist as an issue? Twist  that goes so far as to where the furler line gets carried around the body of the furling drum as the drum rotates.

Yes. Multiple different boats more times than I wish to remember.

Boats that don't have a means of stopping it, it's a question of when, not if, it will become a cluster at the worst possible moment.

The way it stops spinning without this, is relying on tension in each side of the continuous furling line and to a smaller extent, 'rope-memory', in the tack line. Tension is usually achieved by taking the furling line aft to a bungied block.

I have seen that bungie get released and because the luff torsion rope was still loaded with torque the furling line took 10+ wraps around the luff.  That's quite easy to recover from and generally only costs you a podium. The other issue, where you're unfurling and the furler suddenly starts spinning, results in a substantially bigger problem. 

My 2c, just don't use a furler without a 2:1 on the drum or some other means of stopping it spinning (ie a grooved attach).  That Fancor shackle, while it won't be cheap, will be worth every cent. 

PS in your photo I would lash a low friction ring to that stainless plate.  And I would make the bow length of the tack line all dyneema cover or stripped core to make recovery easier and quicker, I would also use a cow-hitched eye splice for the dead end. 

Happy furling :)

 

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Also, as I missed your original question... A suggestion.. 

Lash a low friction ring to that stainless fitting at the end of the prod. 

Then option a

Put an eye splice in your line and cow hitch this to the prod.

After you have set it all up, cranked this on and let the cow hitch settle, stitch it so it cannot open up. 

Warning, this creates a risk that your prod could get crushed, over to you to work out if that is likely based on loads. 

Opton b if worried about pole crush. 

Put a small eye splice in the end. Lash a line around the prod through the eye splice. 

Secure option a or b in place by tying from the stainless fitting to the loop. Finish it with galvanising tape. 

Hopefully the picture helps. 

Screenshot_20201129-190705_Bamboo Paper.jpg

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I am also seeing this attachment for the code sail at the end of the prod being used. The second picture is a close-up of the furler used at the end of the prod. It's interesting that he is not having an issue with the drum assembly trying to twist so far that it wraps the continuous furl line around it, I wonder why this works for some but not others. (He has three furlers, the other two are on a 2:1 and a 3:1 tack downhaul/retrieval line so they would never see twisting with these furlers)

furlers on Prod.jpeg

Single point attachment at end of prod.jpeg

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2 hours ago, 2flit said:

I am also seeing this attachment for the code sail at the end of the prod being used. The second picture is a close-up of the furler used at the end of the prod. It's interesting that he is not having an issue with the drum assembly trying to twist so far that it wraps the continuous furl line around it, I wonder why this works for some but not others. (He has three furlers, the other two are on a 2:1 and a 3:1 tack downhaul/retrieval line so they would never see twisting with these furlers)

Wow, nice boat - where is this?

This will work, up above I said:

Boats that don't have a means of stopping [the furler spinning], it's a question of when, not if, ...

I was not trying to imply that a 2:1 was the only way of stopping the spinning..

What they are relying on here is one of two things, and it's difficult to tell from your photo angles which, but I am guessing that the 2:1 shackle is at 90deg to the furling line?

If so then the eye splice pulls the soft shackle through the low friction ring, the soft shackle then contacts the low friction ring at two points, the added width of the 2:1 shackle creates a triangle and the triangle cannot spin because each side of the triangle opposes the turning force against the ring.

If the 2:1 is in line with the furling line, then they are relying on the fact that the eye splice has two opposing ropes and so the same factors as above occur.  I think this is unlikely - infact I would say that if they had it set up inline, that it would of been assembled wrong and was not optimal - especially if it is possible to pull the soft shackle into the ring as the furler could end up being at 90deg to the boat center.

Risks and mitigations that come to mind:

If the crew forget to really crank this on, eg just pull it down by hand, then when the load goes on the top halyard it will pull that eye splice out of the ring and there will be just one rope - spining could happen - especially if the torque wasn't taken out of the torsion line (this boat probably has a crew that "rarely" makes mistakes and torsion lines are always unloaded before dropping)

if the tack line stretches enough then the triangle could leave the ring - spinning could happen (this boat probably has SK99 lines everywhere so stretch isn't an issue).

If the tack is eased before the halyard - spinning could  happen - (this boat probably has a crew that "rarely" makes mistakes and they get the drop order right every time).

If the furling line is not taught when pulling out the furler it can end up backwards, depending on which way round the soft shackle goes - annoying but won't result in spinning - although this creates an equally bad cluster mess - especially when you discover that you just unfurled your code zero and now the furling line is pointing the wrong way and you have no way of furling it.

This method is a good way to stop the spinning, it's just in my opinion this has more margin for error than a 2:1 off the prod.

There is one other way I have seen and that is a grooved attachment on the prod, the furler is pulled down into that attachment which physically stops the furler spinning.  I have only seen this on one boat at the CYCA and it was a custom built prod with a fancy fitting.

 

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