Single Line Reefing with Floating Block

[jeffoaklief]

I am thinking about switching out Ruf Duck's reefing system to something a little simpler to operate (but possibly more complex in parts and installation).

Does anyone have any experience with a Selden style single reef system (has a floating block)?

Seems to me that there might be some advantages.  

The outboard end could be uncovered spectra since it never goes through a cam cleat or winch.

Fewer lines going to the cockpit (or needing to go to the mast to handle the reefing downhaul)

No need for a reefing downhaul

I foresee some effort to put in two more turning blocks near the gooseneck... but that really is not hard... and (because of you guys) I am getting pretty good at carbon stuff now anyway.

My boom is an old mast Omohundro mast section, so it is pretty deep and seems like there would be plenty of room for the floating blocks... even with my fine tune floating blocks in there already.  If there is a conflict, I am considering getting rid of the fine tune and go back to boom end sheeting with winch assist (the angle of my cam cleat is such that as soon as you put it on the winch it pops out of the cam cleat... so no worries about not easing).

Jeff

[Eric Lindahl]

That looks pretty cool.  Link:  http://www.seldenmast.com/files/595-706-E.pdf.  I have no experience to offer though.  It looks like the the leach is pulling at 2:1 and the luff at 1:1 but with that floating block plate in the boom maybe it all works out, certainly Selden made sure of that.   Also it looks like they specify a cringle in the body of the sail for the luff reef.  Thats interesting.   Seems like a lot of work to set up but if your keeping the boat for years and it makes things easier go for it.  Nothing better than messing around with your boat.

Eric Lindahl

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[Geo Lefler]

Jeff, 

This looks likes a variation of the old 'Jiffy Reefing' system installed on my Gemini, with the addition of the floating car inside the boom. 

Years ago, when I was feeling ambitious, I looked into a somewhat similar kind of single reefing system, with cheek blocks on the outside the boom, but no floating car.  This system had just a single line that ran aft thru the boom - as in most Jiffy reefing systems - up to the the leech cringle, and down to the boom.  But instead of ending the line there with a bowline around the boom, this ran the line through the aft cheek block, forward to a second cheek block, then up to the luff cringle, then down to the goose neck end of the boom (or reefing hook) where it was tied off.  Simple, stupid, and somewhat foolproof. 

But, I figured I'd probably need a winch to pull the line with enough force to make it work, though.

My boom has two internal reefing lines, and I had the grandiose idea that I could put two sets of cheek blocks outside the boom for a two-reef system, with a pair of rope clutches at the single winch.  But I let the whole concept slide as I began to see the difficulty in routing the reefing lines back to the cockpit.  Plus, I'd have to replace the reefing line locking cams at the forward end of the boom with blocks for cockpit routing.  At that point a boom roller furling system began to look more attractive.

I'd be a bit concerned about the Selden system, as you can't easily get to the components inside the boom.  If the floating car - or its blocks - become sticky, sluggish, or frozen when you're trying to reef, what are you going to do?  Regular maintenance would seem the key, which probably would involve removing the boom-end to get to the floating car.

FWIW, I did some googling and found posting on one forum:

https://jeanneau.proboards.com/thread/2598/siezed-sheaves-selden-single-reefing

Good Luck, 

Geo.

[Andrew]

Eric, see if you agree with this thinking:

If the floating block doesn’t move, the leach comes in at 1:1 via an admittedly complicated path. And the luff doesn’t move. 

When the floating block plate moves aft, it’s 2:1. So the luff is 2:1 as it only comes in via the floating block moving. The system is designed so when the floating block is bottomed out on the aft portion of the boom, the tack is where it should be. Or I suppose, it stops when the 2:1 can’t overcome the halyard setting or resistance. 

At that point if the clew hasn’t reached its final destination, it continues in at 1:1 till it’s correct. 

Which finishes first, luff or leach, depends on the dynamics of the system - friction, tension …, but the leach is 1:1 and luff is 1:2. 

One variable might be that our leach tension is quite a bit higher with a square top main. Not sure that’s an issue. 

To not leave the cockpit I think the topping lift would need to be led aft. Raise the boom, much of the leach is taken care easily with 1:1, luff brought down with 2:1. With Jeff’s work on his track, he won’t need 2:1!?

Anyways, any thoughts on that evaluation?

On Jun 16, 2020, at 09:46, Eric Lindahl <ejli...@comcast.net> wrote:



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[Eric Lindahl]

That sounds reasonable to me Andrew.  Its just tricky where to make that floating block bottom out.  With different (reef worthy) winds perhaps one would want more control of the luff tension than just the single setting of the bottomed out floating block.  In any case smarter minds than mine have designed this system.   My F31 cunningham has 8 to one purchase so I'd think Jeff would want more than 2:1, but I think this system is made to be winched down.

Eric

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[jeffoaklief]

Truth be told, it has always been hard for me to work out ratios and forces when complicated block configurations are involved.

I can understand Andrew saying that the clew is coming in at 1:1.  I think the tack is coming in at 2:1 (easier pull than 1:1) but only because I am going to run the downhaul line through the cringe and down to a dead eye on the boom.  The floating block does not affect the tack, I think, because it is just re-routing the line not creating purchase.  Since the tack sees an "easier" purchase it should end up going tight first. (although I suppose both clew and tack will come down somewhat at the same time because with the topping lift on and the halyard down there should not be a lot of resistance with the Tides Track unless I am trying to reef off the wind).  Once the tack is dead ended then the tack purchase is irrellevent since all the "power" then goes to the clew.

Am I thinking about this correctly?

Yes, not much power in the purchase but I am planning on taking the line to the winch.  I already have two clutches at the cockpit winch for this purpose (previously for the clew end reef tension only).

I am guessing that I will need to get rid of my mainsheet fine tune to make room for all this, but frankly even at it's 32:1 it is not that useful, and even though it runs the full length of the 14' boom that is not really much adjustment.  Last year I experimented with using the 8:1,  bringing it in to my hand strength threshold and then taking the forestay sag out with a winch.  Seems to work, and it is simpler.  

Jeff

[Andrew]

Ha! Are we allowed to change our opinion?

Thinking about what Jeff proposed, “I am going to run the downhaul line through the cringle and down to a dead eye on the boom,” made me realize I had forgotten part of the system. 

The bowline from the boom up through the leach cringle and back down is 2:1 by itself. So the system as designed by Selden has 2:1 at both clew and tack (via the moving slider). 

I’d suggest that going up to the luff cringle and then back down to a dead eye on the boom effectively adds 2:1, making the luff portion a cascade system equal to 4:1. 

All likely academic, except like you say, downwind when roach and square top may play an issue, guessing leach > luff?

We all know the risk of how winches disconnect forces from what may really be happening. On my South Pacific trip a rip was put in the brand new “bullet proof” main while winching in the third reef with the vang not loosened (luckily by the captain!? - obviously out of practice with all us ‘trainees’ doing the work). Out came the Sailrite in Rurutu. 

I wonder if only putting 2 or 3 wraps on the winch could act like a clutch and make you look up if too great a tension caused it to slip. 

On Jun 20, 2020, at 20:19, jeffoaklief <jeffo...@gmail.com> wrote:



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[Eric Lindahl]

Andrew and Jeff, I think your ideas make sense.  I've got nothing to add.  Let us know how it works.

Eric

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[jeffoaklief]

Ok.  Are you sure about the 4:1?

If I could figure out how to post pictures to this I would... but I will have to try written description instead.  So... Imagine that there is a block with a 2:1 purchase.  Then, on the part that I am pulling on (say a foot up) I interject a few other blocks.  First, I put a fixed turning block so the line runs left... and then another fixed turning block so the line runs back right the same distance... then another fixed turing block so the line continues the path it would have had without all those other blocks I just added.  I should probably throw some other stuff in there like dividing by your social security and then picking a card from the middle of the deck... but I digress.  I think the resultant is still a 2:1 purchase on the tack.

For some reason, I do not think the floating block in the boom impacts the purchase on the tack.  It does make the apparent line line length shorter or longer though... since I can not see the length in the boom  :).

This all feels like the time, in fourth grade, my dad explained that if I was leaning on a stationary 10 ton boulder, the boulder was "leaning" back on me with exactly the same force... and saying that if I was pushing more than the boulder the bolder would move (and vice versa).  I struggled for years thinking about sentient boulders... their knowing exactly how much to push back without pushing me over.  And what if the boulder was on an incline?  That must be tough for the boulder... just enough force to keep from rolling down the hill and then along comes a kid...

Anyway... I hear you on the winch power thing.  My first thought was that keeping an eye on the draft would be enough... but maybe marking the reef line before hand would be a good idea.  Kind of like the mark you would put on the main halyard to let you know how far to lower.

Jeff

[Shaun Heublein]

Looks like a pretty sweet setup as long as that 'sliding plate' does not get stuck/wedged on anything. For what it is worth the tack is pulled at 2:1 and the clew is also pulled at 2:1 but, with a fair amount of friction due to the line having to slide through the cringle. They do not cascade in to 4:1 for any single point, tack or clew. I would imagine that with the increased friction at the clew, the tack will tend to come down first, unless resisted by the halyard length. You might be able to save room in the boom and simplify things by using a simple low friction ring to replace the entire in-boom plate/block/tack line connection. Just splice the ring into the end of the in-boom tack line and run the clew line through the ring, no plate to jam and no block to seize. That ring could then be really anywhere in the boom as long as it has room to travel within the boom the length equal to the distance from your mainsail tack to reef tack.

[Andrew]

Am I sure? I’m sure someone might be able to convince me of something different, but here’s my (current) thinking (and a new potential wrinkle). 

If I’m following your description correctly, we agree that any fixed pulley that only changes the direction of the line doesn’t enter into the calculation (except to decrease effectiveness via friction etc.). Any pulley that moves will enter into the calculation. 

Let’s isolate the systems by saying the leach/clew is in and the luff/slider hasn’t moved. (If it’s moved, nothings changed, just adds visual complexity.)

As per the Selden design, the luff/cringle only moves if the slider moves. To move it, two lines pull on one moving pulley - 2:1. Confirmed by fact that to make the pulley/slider move one foot you have to shorten two lines a foot each by pulling out two feet. The line ends at the cringle. 

Separately let’s look at your idea of modifying the reefing line so it goes up through the cringle and down to an attachment at the boom (now same as the leach). We have the same scenario as the slider - two lines moving a cringle/pulley - 2:1. Confirmed by same fact that the two lines each have to shorten a foot (2 feet of line) to move the cringle one foot. 

These two systems are set up in a simple cascade (via the slider) so when we combine them we have four lines moving two pulleys by pulling on one line = 4:1. Confirmed by pulling out four feet to move slider two feet, which moves the cringle one foot. 

Moving all that line is the penalty of mechanical advantage. We all see the main sheet pilled on our cockpit floor. 

Thinking about this made me realize one possible problem with your luff modification. The slider has to pull in (or move) twice the gooseneck to cringle distance. I don’t know any of these numbers, but your second reef may require more slider movement than the length of your boom allows? If fifteen feet say, you would need 30’ plus space for any supporting hardware. 

On Jun 21, 2020, at 22:46, jeffoaklief <jeffo...@gmail.com> wrote:



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[jeffoaklief]

Love the ring idea.  Fewer parts and less bulk.  The ring would also be a perfect fit for the coverless dyneema I would use at the clew.   I am going to do that.

I am still not convinced about the 4:1.  Maybe you are right... but I would like you to show your work.  :)

Jeff

[Andrew]

I think you’ll show us! Will be exciting to see. 

On Jun 22, 2020, at 12:51, jeffoaklief <jeffo...@gmail.com> wrote:



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[Shaun Heublein]

Yes, the Selden diagram, as drawn with the tack line terminating on the sail, is 2:1 on both the tack line and the clew line. If you make a small modification to the Selden drawing so that the tack line runs up through the reef tack cringle and back down to the boom instead of terminating on the sail, you will have created a 2:1 pulling on a 2:1 resulting in a 4:1 ratio pulling on the tack cringle. Jeff proposed making several small modifications to the Selden diagram as pictured in the attached file. In this diagram both the tack and the clew are pulled at 2:1 and the block inside the boom will move forward a distance equal to the distance from the clew cringle to the boom.

Hope this helps.

Shaun