Hobie-style Jib Tensioner

Moderator: GreenLake

Hobie-style Jib Tensioner

Postby tomodda » Sun Jul 21, 2019 12:15 am

Hi Folks:

Too hot and windless to sail. Did some overdue rigging work today - my new jib tensioner:

IMG_20190720_222532-01-768x1024.jpeg
Jib tensioner
IMG_20190720_222532-01-768x1024.jpeg (203.22 KiB) Viewed 957 times


Please excuse the night shot, I waited till sundown to work. And don't mind the mess! Unrigged lines all over the place.

Anyway, this is the front of the mast and the port side of the cuddy roof, looking aft. The blue-flecked line is the halyard, and goes in a zig-zag. Down the mast, into a spare fiddle block on its largest sheave, over a cheek block (near my yellow Band 1 marker), down to a bronze foot block and back to a horn cleat. The tensioner/fine tune is the grey-flecked line, it starts at the becket on the fiddle block, goes to a cheek block at the base of the mast, back to the fiddle block, down to a deck block and back to a cam cleat. The fiddle block moves, the two cheek blocks are stationary. The exact angles and position of the blocks were tested out to avoid rubbing or jamming. As it's an external halyard, I also had to watch out to leave some clearance by the spinnaker pole ring. Tight quarters! But I got what I wanted - all jib controls to port, mains'l controls to star, vang down the middle.

Testing on land went great, a good tug on the tensioner leaves the halyard bowstring tight, it twangs! Probably more than I want to tighten it in practice, but good to know that I have the ability.

Hope to test out on the lake tomorrow, we're supposed to have 12kt winds. We shall see...
Last edited by tomodda on Sun Jul 21, 2019 10:13 pm, edited 1 time in total.
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Re: Hobie-style Jib Tensioner

Postby jalmeida51 » Sun Jul 21, 2019 2:44 pm

Hi Tom, I have a question for you, What prevents the fiddle block from jamming up or not staying in position when there is no tension on the halyard, when you drop you jib? Will the fiddle block go back into position when you hoist the jib? Or do you have to hold the fiddle block by hand to get it in the right position while you hoist the jib? I can see your system working if the fiddle block rides up and down on a track. This would prevent it from flopping over and jamming the halyard or tensioner. Please let us know how your test sail went. Thanks, John
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Re: Hobie-style Jib Tensioner

Postby GreenLake » Sun Jul 21, 2019 8:12 pm

I'll post a picture of mine when I get a chance. It looks like a toy compared to yours :)

You have 3:1 in the rigging of the tensioner and a 2:1 cascade the way you pull on the jib sheet. That's 6:1. You should be able to get some serious tension with that one. Mine's a simple 2:1 using 2mm line :shock:

When I tested it, it seemed to work fine (still working on final cleat position). I've been meaning to take a picture at the ramp, but something always distracts me ;)
~ green ~ lake ~ ~
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Re: Hobie-style Jib Tensioner

Postby tomodda » Sun Jul 21, 2019 10:13 pm

@John:

Good question, I'm also wondering how this rig will behave when on the water, not to mention when I unstep the mast for trailering. That being said, I usually don't have lots of slack in the jib halyard, even with the jib down, because I use a downhaul. And the fiddle block is right up against the mast, so there's really not a lot of room for it to get flipped around. The total "travel" - halyard slack to tensioner all the way tightened - is only a tad over 4 inches. All this work for 4 inches! :)

Nevertheless, I went and tested slacking off the halyard enough to tangle the fiddle block. I had to slack it off till the block hit the cuddy top before it flopped over, so I think we're good here. If not, I was already thinking of rigging an eyebolt right beneath the yellow band and a small length of bungee to hold the block up. We'll see after a few sails.

Unfortunately, no sailing today. Fluky wind and WAAAAAY too hot, 100 degrees! OK, that's nothing for you TX200 sailors, but it's heat stroke risk for me, no thanks. Heat wave is supposed to break on Tuesday, then we'll see.

@GL:

Yes, I probably overbuilt. I was going to use a single plain block shackled to a single becket block for the "moving part," but then I got my paws on that fiddle block (leftover from another project) and figured that I could use it "upside down and backwards," so to speak. The cheek blocks are Shaefer 3-series, one curved, one flat. Both were ebay finds, so considerably cheaper than retail. The rest - deck blocks, cleats, foot block - were either original to the boat or parts I bought during a super-sale from CLCboats.com (great site for dreaming!).

Note, my original plan was to use smaller stuff from Racelite - I love them but am always confused/dubious about what working loads their blocks can handle. I guesstimate a SWL of 600lbs on their blocks. So quick calculations, it's a 3-1 pulley, I can easily put a 200 pound pull on it when really tightening down, throw in the mast forces when bouncing over waves... starting to get risky. So overbuilt it is. The cheek blocks cost me $30 each with shipping, the fiddle block I'll call "free" and the rest is sunk costs. So $60 to tighten my jib halyard by 4 inches, don't tell my wife! :roll:
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Re: Hobie-style Jib Tensioner

Postby GreenLake » Mon Jul 22, 2019 12:09 am

Mine is rigged so the halyard itself is always "hand tight". Should my tensioner fail, all that would happen is that the halyard loses a bit of tension; sail stays up. And I'd probably heave to and tighten it some more before continuing.

I very much doubt that I can pull 200lbs on a halyard (mine is cleated on the mast). I figure, if I get 50, w/o the tensioner thats pretty good. Doing 2:1 if I can put 30-40lbs on my tensioner line, I get 60-80 lbs on the halyard, that seems to be enough to take the scallops out in the winds I sailed it in. Just guesstimating, but my tensioner line is 2 or 3mm.

Also, one upper limit on halyard loads is given by the wind load at which your boat will capsize. (Once it heels far enough, that limits further wind force, down to 0 when you are in the water). There some dynamic factors on top of that, if you slam into waves etc., but that's a limit that yacht designers actually use (less nowadays perhaps with ropes so strong that you need to oversize them just to be able to grip them).

Going down to 2 or 3mm is probably a bit aggressive, but the block has at least 200lbs working load (it was spec'd on the label and seemed reasonable when I selected it). And it would take a 6mm line, if I felt like it. (I did think I looked up the MWL for the line, concluded it was going to be fine and forgot it promptly ;))
~ green ~ lake ~ ~
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Re: Hobie-style Jib Tensioner

Postby tomodda » Mon Jul 22, 2019 8:30 am

GL:

Ahn, yes.... gossamer-thin spectra/dyneema/etc halyards. I was considering going that way, I know that they are certainly strong enough. Two things hold me back - a nasty incident, 30 years back, with spectra kite-string (I'll do anything that involves playing with wind!) which left a permanent scar on my torso and fear of thin lines under high tension, and how do you splice the 2mm stuff onto something that you can hold?!? Yes, I know there are ways, but I'm happy with my Sta-Set halyards for now. I may go to 10mm amsteel sometime in future and splice it into a grippy tail (easier than with the thin stuff). Perversely enough, I'm using 2mm "magic thread" for my 1:2 jib downhaul - since it goes UP the forestay when the jib is up, I wanted to minimize windage, but it's not under any sort of real load.

As for forces on the halyard, I disagree with the wind load at capsize being the maximum load. I'd think that the entire rig - jib, mainsail, mast, boom - jerking back on the forestay when you hit a wave is greater than just overcoming the righting moment (capsize). I have a wire luff on my jib, so when the halyard is really taught the forestay itself is slack - all load on the halyard and associated hardware. Likewise, my statement "I can pull 200lbs" is purely because the halyard is led to the deck and I can give it short, sharp tugs with my entire 250-lbs of bulk + a little muscle. Wouldn't be possible if halyard was cleated at mast.

Speaking of calculations, I wrote that at max tension my fiddle block moves 4 inches. But how much stretch am I taking out of the halyard? It's going thru a 1:2 purchase as it goes over the fiddle block, so is it 8 inches? Does it stretch equally on both sides of the block? How do I even measure this? Obviously all I really care about is getting the scallops out of the jib luff, so who cares? But I'm curious, will give it a think.

Looking forward to seeing your setup. Maybe I'll downsize one day and re-purpose my cheek blocks as bottle openers ;-)

Tom

PS - The other justification for this whole tensioner setup is peace between me and my regular crew. I'm always grumbling at him about jib set - "Hey, can you give the jib halyard another tug please? Look at those scallops.... I know you're trying but PUT YOUR BACK INTO IT!" and the conversation quickly degenerates from there. It doesn't help that he only weighs 150lbs soaking wet and he considers keel-hauling a nice way to get his back scratched. All that being said, we have a lot of laughs on the water and he's a great helmsman as well, so we often swap places and I get a chance to set my sails properly.
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Re: Hobie-style Jib Tensioner

Postby GreenLake » Tue Jul 23, 2019 2:04 pm

Well, as for wave forces: sailing mostly on protected waters, so little in the way of waves (other than wakes). If my tensioner pars, it won't be a disaster and I will have learned something. I don't have "free" lines that are very thin. ("free" means stuff with enough tail to wrap around me - I do know better than wrapping any of those around hand/fingers :) ) Mostly things like outhauls, reeflines etc. And my actual halyards are 1/8 or 3/16" (Amsteel) with wider tails - it's not that impossible to splice a nice braided tail onto Amsteel. You'll find instructive descriptions on https://L36.com.

(A great site, by the way).

You may have to experiment which ratio of diameters works. For one of my halyards, I spliced a bit of wider Amsteel at the end, so I would be able to get the tail diameter I wanted. It was supposed to work per instructions, but the dimension of the braided rope must have been off ever so much and as Amsteel absolutely will not stretch there was no way I could make it work without an "adapter" piece. Still, a fun project.
~ green ~ lake ~ ~
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Re: Hobie-style Jib Tensioner

Postby GreenLake » Wed Jul 24, 2019 10:27 am

Here's the promised picture of my "minimalist" jib tensioner.
2679
The tensioner is the thin blue line. It goes from a fairlead up to a block that hooks into a Prusik loop. The Prusik loop sits on the splice where the halyard changes from Amsteel to double-braid. Otherwise it tends to slip. Alternative would have been to tie a loop into the halyard. Simply hooks in so quick to rig/derig; nothing to string. 2:1 so far sufficient to get the desired tension. The line is 3mm, and at half the halyard tension I find I can still pull it OK. Without the tensioner added, the jib halyard is as before, so if the tensioner fails the sail stays up.
~ green ~ lake ~ ~
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Re: Hobie-style Jib Tensioner

Postby tomodda » Wed Jul 24, 2019 6:24 pm

GL:

Very nice, certainly one way to do it! Prusik knot solution is very elegant (along with your famous mast-stepping sleeve). I'm also worried about how much rigging effort my tensioner is gonna be when stepping/unstepping the mast. Well, go time is tomorrow, 3PM, we shall see. Only 7knot winds forecast, but 78 degree temps! Positively fall-like after two weeks in the Carolina steam-bath!

Off topic, an observation, a thank you, and a question (not in that order).

-I first found this forum when I was considering the DS as my next boat and wondering how I'd step the whole (no tabernacle) mast, single-handed. Found your sleeve solution and decided that I could do this. Then I wound up buying a DS with a tabernacle anyhow, but if it wasn't for your post about how you've done it, I'd be sailing a Sunfish or something tiny. Thank you!

-I've visited the L-36 site a lot, especially for tips on rigging a vang (my 20:1 is based on his), sail trim, and inhaulers. I finally took the time to look thru his ENTIRE index of articles and there are some really good tips. I was particularly struck by how he is attaching his halyards to headboards with a simple toggle instead of a shackle - saving a good two inches of halyard length! and his articles about rigging the mainsheet system. We obviously don't need a gross/fine trim for the mainsheet, but food for thought!

-Question, when you step your mast, I assume that the side-stays (shrouds) are not rigged. What keeps the mast steady while you rig your stays? Are the partners enough? With a tabernacle, I keep my side-stays rigged all the time, pull the mast up using my jib halyard attached to the stem-head and then rig the forestay before taking the halyard off the stem. If I dont have both sidestays rigged, disaster ensues. So, can you walk me thru your mast-raising process?
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Re: Hobie-style Jib Tensioner

Postby GreenLake » Thu Jul 25, 2019 3:07 pm

Thread drift, here we come.

Glad you ended up with a DS!

I attach my main with a variation of the L-36. I have an eye at the end, wider than fits the headboard. I do the same luggage tag hitch tied on the bight, using the eye as a stop. Needed for my sail, it's too tall otherwise.

Mast raising: I insert the foot into the sleeve, push up, hold mast steady while standing in the cockpit (more of a knack, not entirely strength, but reach helps), then lower, mast step+partners secure free-standing mast while stays are attached. (A helper on deck is not needed for me, but I can see how somebody might like assistance).

It's really nice to not have to worry about the mast once it's on the step.
~ green ~ lake ~ ~
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Re: Hobie-style Jib Tensioner

Postby tomodda » Thu Jul 25, 2019 6:05 pm

GL:

Thanks for the explanation. Yes, there is a knack to mast-raising. If everything is steady side-to-side (sidestays properly attached and at right length), I can raise it with one arm and hold it while snugging everything down. That's THIS year, I was a lot weaker last year - recovering from health issues - and needed a tackle to raise it. It's all good, the Daysailer has been part of my recovery, gives me something to strive for.

<END THREAD DRIFT>

Tom
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