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Why slack rigging

Printed From: Yachts and Yachting Online
Category: Dinghy classes
Forum Name: Technique
Forum Discription: 'How to' section for dinghy questions and answers
URL: http://www.yachtsandyachting.com/forum/forum_posts.asp?TID=12651
Printed Date: 20 Oct 17 at 11:53am
Software Version: Web Wiz Forums 9.665y - http://www.webwizforums.com


Topic: Why slack rigging
Posted By: ColH
Subject: Why slack rigging
Date Posted: 06 Feb 17 at 8:20pm
There's a fair few threads on here which allude to some classes which favour slack rig tension. I'd like to understand the reason(s) why this is preferred, what's the technical reasoning?



Replies:
Posted By: Rupert
Date Posted: 06 Feb 17 at 9:07pm
Because it is faster...

In the case of the Firefly, it allows the rig forwards offwind and back upwind, using job tension and kicker/mainsheet. Sails are cut for this to work, as it means old wood hulls aren't pulled apart.

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Firefly 2324, Lightning 130, Puffin 229, Leader, Topper 44496, yellow Minisail


Posted By: Sam.Spoons
Date Posted: 06 Feb 17 at 10:19pm
It seems that on singlehanders like Solo, Streaker and Blaze (and others) the slack shrouds allow the boom forward enough to allow by the lee running. If you want an extreme case just look at a Star bearing away onto a run. If a boat has a spinnaker and/or trapeze(s) a certain amount of rig tension is required to keep the stick in the boat.


Posted By: sargesail
Date Posted: 06 Feb 17 at 10:48pm
Originally posted by Rupert

Because it is faster...

In the case of the Firefly, it allows the rig forwards offwind and back upwind, using job tension and kicker/mainsheet. Sails are cut for this to work, as it means old wood hulls aren't pulled apart.

And the other thing that happens is that the leech is opened.


Posted By: Paramedic
Date Posted: 07 Feb 17 at 8:09am
On some of these classes (Solo) the rig is essentially unstayed, with the shrouds/forestay used to limit the amount the mast can bend. When these classes were first designed it was probably a much cheaper way of doing it than a bespoke unstayed alloy mast like in the Finn/OK and more robust than the unstayed wooden spars in the same classes. These boats were designed to be built (or at least finished) in your garage/living room/kitchen so the latest hi tech stuff was neither accessible or appropriate and in those days may not have been significantly better.

Nowadays you wouldn't do it, but it was how things were done in those days. It works so nobody has bothered to push for rule changes. 

I may be doing Mr Holt down slightly, but things like getting the boom out squarer were probably more convenient side effects than design features! Fittings, ropes and in many cases hull structure were not up to rig tensions of the sort that we run today.


Posted By: Sam.Spoons
Date Posted: 07 Feb 17 at 9:11am
I'd be interested to see a 1960s tuning guide for a Solo. I have no firsthand experience (though I'm just about old enough) but I suspect Solo rigs were designed to have some tension originally particularly as the first boats had wooden masts. I doubt anybody would have tolerated a slack rig by today's standards. 

I do remember that sailing by the lee was absolutely beyond the pale, nobody in their right mind would allow it to happen so you may well be right that JH would't have considered that an issue.

Edit :- this is a fascinating read  http://www.strawberrymarketing.com/publishing/firefly75/FIREFLY%2075%20years.pdf" rel="nofollow - http://www.strawberrymarketing.com/publishing/firefly75/FIREFLY%2075%20years.pdf  but notice the boat in the first pic has diamonds so unlikely to be a slack rig.


Posted By: Rupert
Date Posted: 07 Feb 17 at 10:15am
On Firefly Reynolds masts (the ones with the wooden top) diamonds were tight, but shrouds loose. The mast rotated, so tight shrouds would have prevented that happening easily. Once the rotating Proctor mast came out, they were so stiff, even the diamonds became slack.

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Firefly 2324, Lightning 130, Puffin 229, Leader, Topper 44496, yellow Minisail


Posted By: Sam.Spoons
Date Posted: 07 Feb 17 at 10:19am
Interesting stuff Rupert, I don't have a desire to own another old wooden boat but it's fascinating reading about them. Smile


Posted By: iGRF
Date Posted: 07 Feb 17 at 12:01pm
Having floppy rigging enables the rig to act a little bit like a racing windsurfer rig, i.e back for upwind and forward for off wind, it also helps in light wind enabling soft sails to heel and keep shape without having to heel the boat on hulls that don't like to be heeled.

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http://www.edgeactionsports.co.uk" rel="nofollow - Beanies, Bike Helmets & Snow accessories to clear


Posted By: Sam.Spoons
Date Posted: 07 Feb 17 at 1:07pm
It looks like the very extreme forward rake of the Star class downwind gets the airflow moving up the sail and, maybe, keeps it attached for longer?


Posted By: Rupert
Date Posted: 07 Feb 17 at 9:16pm
Till the mast crumples like spaghetti!

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Firefly 2324, Lightning 130, Puffin 229, Leader, Topper 44496, yellow Minisail


Posted By: Sam.Spoons
Date Posted: 08 Feb 17 at 12:46am
LOL


Posted By: ColPrice2002
Date Posted: 08 Feb 17 at 9:04am
Both my Fireflys were fitted with rotating masts, the fastest setup was to have the forestay slack enough that the mainsheet could be block to block upwind. For downwind, there was a jib tensioner to pull the rig forward and tighter the jib luff.
If one forgot to release this upwind, the boat was significantly slower.

As Rupert states, the Reynold masts needed tight diamondstays - the section as too thin to be self supporting downwind (remember that the mast rotated).
The later Proctor masts were more robust, nowadays, the mast is fixed with spreadrs, so it's a different setup.

With regard to the Solo,one of the effects of slack rigging is that the mast can sag a bit to leeward, tending to open the leech upwind. With the fully battened sail, I suspect it is too easy to hook the leech.

Colin


Posted By: zippyRN
Date Posted: 11 Feb 17 at 3:43pm
Originally posted by ColPrice2002



With regard to the Solo,one of the effects of slack rigging is that the mast can sag a bit to leeward, tending to open the leech upwind. With the fully battened sail, I suspect it is too easy to hook the leech.

Colin

what section ali mast  was the Solo orginally  built  with ?  given there are people sailing them now with D/ sleeved D / D+  and M7  masts -  all fairly stiff and in the case of a D+ esigned to be extra stiff  in the Ent   with it's deck stepped  Mast  where as a lot of the olderboats look to have C or similar masts 


Posted By: Paramedic
Date Posted: 11 Feb 17 at 9:27pm
Ive not seen a normal D on a Solo for years. I would imagine the gold masts are Ds and Cs not seen a B but i bet they were used too.

Anything semi recent wood be a Cumulus/C/Sleeved C/D+ or Superspar M1/Skeeved/M7


Posted By: Rupert
Date Posted: 11 Feb 17 at 10:08pm
I remember Holt round masts with the track riveted on. Can't believe they were very stiff, but no real idea.

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Firefly 2324, Lightning 130, Puffin 229, Leader, Topper 44496, yellow Minisail



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