That Ken not Barber Hauler Jock Strap thing
Printed From: Yachts and Yachting Online
Category: Dinghy classes
Forum Name: Dinghy development
Forum Discription: The latest moves in the dinghy market
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=10720
Printed Date: 18 Jul 25 at 7:48am
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Topic: That Ken not Barber Hauler Jock Strap thing
Posted By: G.R.F.
Subject: That Ken not Barber Hauler Jock Strap thing
Date Posted: 21 Feb 13 at 9:43am
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So, trade shows over for a bit, I'm hoping to get back on the water and the last thing I wanted to sort out was that elasto strap thing that keeps the sail & boom out and forward when clew first downwind. Having a dementia riddled brain these days, I've completely lost the thread (as well as the plot) and forget which boat it was that I saw pictures of them using it, something I was probably ridiculing at the time. OK maybe? So if anyone has one of these things, useful hints and tips, what size elastic, where do you fit it so it works both ways, judge the tension etc? Oh and what it was called, Dan did give it a name, some initial like J strap after jock who invented it or similar.. Thanks in grateful anticipation, maybe you can stop beating up the furballers and exercise your brains for a bit.. ------------- https://www.ease-distribution.com/" rel="nofollow - https://www.ease-distribution.com/ |
Replies:
Posted By: rb_stretch
Date Posted: 21 Feb 13 at 10:14am
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Used on the Solos. It is normally tensionable as well. BTW. I regularly race against the EPS that was at the Perisher and BM this year. He's a good sailor and has never found the need to use one as far as I can tell.
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Posted By: tick
Date Posted: 21 Feb 13 at 10:21am
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Well my boy, sorry to say that Solo's have them. It's quite simple. A long bungee which passes through a pulley at the bow, round each side of the mast and attaches to the boom....or is the pulley on the boom....anyway, in theory it holds the boom out down wind when you are heeling to windward. It stops gravity hurling the boom across and removing your head. I have seen them tried on Lightnings but on boats without shrouds the boom can be shoved in front of the mast where gravity will keep it there anyway. The OPS or what ever it's called only has lowers dosen't it and that rather natty bearing. Do they interfere with forward movement of the boom?
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Posted By: transient
Date Posted: 21 Feb 13 at 10:27am
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Yep, OKs use them......Looks like a bit of 10mm http://iokda.wordpress.com/2012/05/28/classic-ok-for-sale/# - http://iokda.wordpress.com/2012/05/28/classic-ok-for-sale/#
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Posted By: G.R.F.
Date Posted: 21 Feb 13 at 10:50am
Never met him but have followed his progress, hence feeling the need to do something about making the boat faster, this will solve a little problem I have in light weather, he, like me, got himself beaten by a Solo in light weather and that can never be allowed to happen again, following an incident I had after a late start and issues with the boom not staying forward. No Solo should ever beat an EPS and be allowed to live. ------------- https://www.ease-distribution.com/" rel="nofollow - https://www.ease-distribution.com/ |
Posted By: G.R.F.
Date Posted: 21 Feb 13 at 10:57am
Thanks, that's sort of it, I still can't work out how that can function, as it goes one way it pulls the other, then it's not the only crazy thing about that boat. Geez how can that work, the centreboard, therefore the centre of lateral resistance is ahead of the cockpit, no, I don't want to even start on how wrong that all is, just let me concentrate on the task to hand, a system to keep the boom open and ahead of the mast when I need it. So, did someone say 10 mil, is that stuff 10 mil on the not exactly OK in that picture? ------------- https://www.ease-distribution.com/" rel="nofollow - https://www.ease-distribution.com/ |
Posted By: transient
Date Posted: 21 Feb 13 at 11:08am
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My estimate of shockcord dia was a little of out. Try this link: http://www.mpipks-dresden.mpg.de/~broecker/OKsite/fittingout.html#shockcord - http://www.mpipks-dresden.mpg.de/~broecker/OKsite/fittingout.html#shockcord
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Posted By: JimC
Date Posted: 21 Feb 13 at 11:12am
The block at the bow is the crucial thing to make it work, because it means that the tension is equal each side. Thus with the boom on the centreline it does nothing, because the force on each side and the leverage is identical. However once the boom is let out a bit, on the lee side the shockcord is pulling direct from the boom to the bow, but on the windward side the shock cord is pulling along the line of the boom because its touching the mast. Thus although the force exerted by the shock cord on each side of the boom is still identical, because of the block, the leverage is much greater on the lee side because on that side the force comes at a good angle to the boom, but on the windward side its coming directly along it. |
Posted By: Do Different
Date Posted: 21 Feb 13 at 11:21am
| It will work, geometry, just draw it out plan view with a pulley on the bow so tension is equal on all three side and you will see the forces n action. (thinking about it I guess it would also work without the pulley) |
Posted By: rb_stretch
Date Posted: 21 Feb 13 at 11:43am
Unfortunately many of us suffer that fate every light wind race. Certainly in our club, we know if it is a drifter the Solos are going to win. I've even seen a Solo sail straight past an RS300 on the water, both with good helms. |
Posted By: pondmonkey
Date Posted: 21 Feb 13 at 12:53pm
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I've even seen a Solo sail straight past a Foiling Moth when the conditions were right... [tube]_M1pgq667bA[/tube] ------------- |
Posted By: G.R.F.
Date Posted: 21 Feb 13 at 1:32pm
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Well that's as maybe, but that is now history, once Kens jock strap is in place alongside my new sail, it will never happen again - ever. And if it even looks close, then it'll simply be a case for t-bone ramming, another solo graphic on the gunwale and off to report it on the Laser hall of fame site. ------------- https://www.ease-distribution.com/" rel="nofollow - https://www.ease-distribution.com/ |
Posted By: gbr940
Date Posted: 21 Feb 13 at 3:18pm
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All the Finns use them as well...and I seem to remember when I had mine going to Aladdins Cave in Port Solent and finding the thickest shockcord they had which was about 8mm, lead from the kicker to the block at the bow and back the otherside.
Hope that helps a bit ------------- RS400 GBR1321 |
Posted By: G.R.F.
Date Posted: 21 Feb 13 at 3:35pm
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Thanks gbr940 it's coming back to me now the other thread we had on the subject, the thicker the shock chord, clearly the greater assistance for a bit of post kinetic reset action.. Solo's they're not allowed kinetics are they? Not good for them at their age... ------------- https://www.ease-distribution.com/" rel="nofollow - https://www.ease-distribution.com/ |
Posted By: hughsheehy
Date Posted: 21 Feb 13 at 5:20pm
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The shock cord thingy is called a "JC strap". If you search on Finn or OK pages you should find lots of info on how to fit them. Basically the fattest shockcord your chandler sells from one side of the boom, outside everything, through a block on the bow, back to the boom. Oh, and take it off on windy days because it can complicate capsizing. H |
Posted By: fab100
Date Posted: 21 Feb 13 at 5:58pm
Grumph (that's GRF, Hugh) never capsizes Oh hang on, falling-in. Was n't that why he sold his 100?  ------------- http://clubsailor.co.uk/wp/club-sailor-from-back-to-front/" rel="nofollow - Great book for Club Sailors here |
Posted By: hughsheehy
Date Posted: 22 Feb 13 at 1:12pm
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Well if he never capsizes he's a better sailor than I am. Or he never sails in strong winds...or maybe just never gybes in strong winds. The JC Strap is great in light airs and makes downwind sailing much neater but it needs to be TIGHT to work properly. The problem arises if it's on when you capsize in a blow. It can pull the boom out to the side so instead of the boat lying head-to-wind after you right it, it's inclined to turn side on to the wind and capsize again. And that's a right pain in the a··. Boats like the Finn and OK, with the mast right up on the bow, are probably particularly affected. H _______________________ http://PortApproach.com - Port Approach |
Posted By: G.R.F.
Date Posted: 22 Feb 13 at 3:39pm
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Don't listen to him Hugh I'm perfectly as capable of capsizing as the next man and have chucked myself in even as recently as a month ago in this freezing bloody weather, so that's really helpful info, getting the EPS back up again can be problematic because of some of the strange and unexpected ways it goes in to windward, usually by over enthusiastic sailing by the lee and getting headed into a turn. (Should have gybed earlier) So I can see this strap will need a control lead back to the boat to release the pulley tension. ------------- https://www.ease-distribution.com/" rel="nofollow - https://www.ease-distribution.com/ |
Posted By: hughsheehy
Date Posted: 22 Feb 13 at 9:06pm
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There was a good discussion of JC Straps recently on the OK Dinghy forum, where it was me asking the silly questions... http://www.okdinghy.co.uk/phpBB3/viewtopic.php?f=4&t=1038 H ____________________ http://PortApproach.com - Port Approach |
Posted By: GybeFunny
Date Posted: 23 Feb 13 at 7:14am
| When I have see these straps on Solos I notice that that the elastic puts a forward and slightly downward force on the boom when on a run due to being attached to the bow which is lower than the boom. This prevents the leech opening in the very light winds. Is this just something you have to put up with in exchange for the convenience of not having to hold the boom out with your foot? |
Posted By: RS400atC
Date Posted: 23 Feb 13 at 11:05am
I sailed a Solo with this bit of elastic about thirty years ago, so memory may be a little suspect. As far as I recall, the tension had to be enough to hold the boom out when it was raised by heeling to windward on a run. So it's acting mostly against a minor component of the boom's weight. So I would hazard a guess that the weight of the boom is adding a lot more leech tension than the elastic. In those days of course we all used big diameter plain bearing mainsheet blocks, which were actually quite low friction. On a boat with a tight rig, you could try attaching the forward end to the forestay at boom level? With a gnav, could you make it lift the boom? On a keelboat, you might do this with a topping lift if you are running with a preventer due to sea state. |
Posted By: Lukepiewalker
Date Posted: 23 Feb 13 at 5:02pm
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On a Finn or an OK you'd need an awfully long leg.... Certainly on my Finn the downward component never concerned me... ------------- Ex-Finn GBR533 "Pie Hard" Ex-National 12 3253 "Seawitch" Ex-National 12 2961 "Curved Air" Ex-Mirror 59096 "Voodoo Chile" |
Posted By: hughsheehy
Date Posted: 24 Feb 13 at 7:55am
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Any downward component is tiny, particularly in an OK or Finn where the boom is quite low. In a solo it'd still be minimal H ------------- _________________ __________________________ http://www.portapproach.com - Port Approach - Casual Gear for Serious Sailors |
Posted By: RS400atC
Date Posted: 24 Feb 13 at 11:36am
| I think some people over the years have used quite strong bungee, to overcome the friction of the mainsheet. I think that's wrong, you don't want the sail held out when the boat has picked up speed in a puff, then the wind goes forward after the puff, leaving the main as an airbrake. |
Posted By: Roger
Date Posted: 24 Feb 13 at 12:26pm
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I think you are all over complicating this issue, the bungee exerts very little downward force and as the boom moves further from the center line that minor force would drop even further as that reduces the tension on the elastic. I have sailed with one of these on a modern Solo for the last 3 years, it does what it is supposed to in light winds and is never a problem at any other time..  |
Posted By: hughsheehy
Date Posted: 26 Feb 13 at 9:50pm
The JC strap can be a little annoying - at least on an OK - on a slipway because it pulls the boom out to the side of the boat quite effectively. Makes the boat tend not to sit calmly head to wind. Similarly, if it's windy and you're likely to capsize then it can cause hassle after a capsize. The boom pulls out to the side and the boat is slightly more difficult to right. Simple solution though. Just disconnect it as soon as there's any wind. H ------------- _________________ __________________________ http://www.portapproach.com - Port Approach - Casual Gear for Serious Sailors |
Posted By: RS400atC
Date Posted: 26 Feb 13 at 11:19pm
| Can you pull the front pulley of it to the bow with another block and a cleat? |
Posted By: JimC
Date Posted: 27 Feb 13 at 8:51am
On my vintage moth I just have the block attached to the bow with a hook... Means you can't pull it off/on on the water but its a lot less hassle than more strings. |
Posted By: G.R.F.
Date Posted: 27 Feb 13 at 8:56am
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I've already got quite a lot going on with the bow cleat ever since I had that incident when the mast fell down, but I had envisaged an on/off pulley which I pulled tight to engage and slackened when I didn't need it, it maybe could double as a redundant safety so the mast doesn't fall completely down again. At the moment I have an adjustable rake thing, backed up by a bit of spectra so if I let it all go or it slipped through the cleat, the mast won't fall completely down. Very traumatic that, not sure what was worse, the shock of it, or being rescued by girls sailing on a puddle, I still wake up screaming some nights... ------------- https://www.ease-distribution.com/" rel="nofollow - https://www.ease-distribution.com/ |
Posted By: pondmonkey
Date Posted: 27 Feb 13 at 9:00am
I plan to fit one this weekend, I'm not sure what the total elastic required will be, but I guess you want enough tension across the centreline, but nothing like maximum stretch. ------------- |
Posted By: Roger
Date Posted: 27 Feb 13 at 9:59am
Can't help with the length, but I'd guess 3-4m would be sufficient, very powerful bungee, 10mm diam from memory. Tied to the kicker take off point on the boom one end, down round a suitable block tied to the bow and with a metal hook on the other end so you can quickly attach to the same point as the other end after hoisting the main, I can check at the weekend but I guess I only have to stretch mine 18 inches to 2 foot max, but its very powerful bungee. |
Posted By: pondmonkey
Date Posted: 27 Feb 13 at 10:04am
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cheers Roger... I bought the bungee from P&B, pretty fat stuff. No need to measure, there's plenty of Solos at the club with them so I can just mimic one of their set ups. I'm sure I'll have a suitable block & hook somewhere. ------------- |
Posted By: Lukepiewalker
Date Posted: 27 Feb 13 at 10:11am
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Mine used to attach to the mainsheet block attachment straps on the boom, a couple of hooks. Never capsized it so can't comment on the ease of release while under duress.
------------- Ex-Finn GBR533 "Pie Hard" Ex-National 12 3253 "Seawitch" Ex-National 12 2961 "Curved Air" Ex-Mirror 59096 "Voodoo Chile" |