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Why slack rigging

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ColH View Drop Down
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Post Options Post Options   Quote ColH Quote  Post ReplyReply Direct Link To This Post Topic: Why slack rigging
    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?


Edited by ColH - 06 Feb 17 at 8:21pm
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Rupert View Drop Down
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Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post 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.
Firefly 2324, Lightning 130, Puffin 229, Leader, Topper 44496, yellow Minisail
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post 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.
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Post Options Post Options   Quote sargesail Quote  Post ReplyReply Direct Link To This Post 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.
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Post Options Post Options   Quote Paramedic Quote  Post ReplyReply Direct Link To This Post 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.


Edited by Paramedic - 07 Feb 17 at 8:12am
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post 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 but notice the boat in the first pic has diamonds so unlikely to be a slack rig.


Edited by Sam.Spoons - 07 Feb 17 at 9:26am
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Rupert View Drop Down
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Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post 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.

Edited by Rupert - 07 Feb 17 at 10:16am
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post 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
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post 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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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post 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?
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