Adjustable Shrouds on the Supernova

Tuning the Supernova Dinghy

Adjustable Shrouds on the Supernova

Postby Pete1177 » Thu Aug 25, 2016 1:32 pm

I have emailed current Class members regarding this year's AGM and the topics under 'Any Other Business' for discussion. One of these is to discuss the possibility of adjustable shrouds. Cliff and Gavin have been working on the concepts and have made a proposal which was attached to the Member's email. The proposal is also downloadable from this website http://www.supernovadinghy.org/post/notice-of-agm.

We would welcome comments from members and other Supernova sailors about the proposal and I have created this topic as a 'sticky' to allow others to post their comments on this forum. Please feel free to ask questions if you need clarification.

Pete
Secretary, Supernova Class Association.
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Re: Adjustable Shrouds on the Supernova

Postby IainWilson170 » Thu Aug 25, 2016 5:01 pm

Just read the download and I think I get most of it. However doesn't advantage 2. Contradict myth 2. ?

One point I would make regarding these type of upgrades concerns those sailors who will benefit the most. It could benefit the better sailors more than the less good. An example is adjustable lowers- I reckon there are only a handful of sailors in the fleet who's overall game is good enough to squeeze the advantage from this system meaning the best get quicker and the rest carry on figuring out how to stay upright/ which way to go etc. So if it can be shown that it is an upgrade benefitting All sailors then fine.

I would say that if it is an addition to the adjustable forestay it will give sailors one extra thing to think about benefitting the top sailors more. If it is instead of the adjustable forestay and it is better than its a good progression.

Can't be at the agm as I am working but hope you all have a great inlands.

Iain 1147
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Re: Adjustable Shrouds on the Supernova

Postby Merlin » Thu Aug 25, 2016 7:23 pm

I too have been experimenting with adjustable shrouds, just like Cliff and Gavin. However, I have been down the one string route. There seems to be some confusion about a one string system and to say it will open the door to greater innovation is incorrect. There is nothing to add to the system; the kicker system remains static whatever the rake, and therefore rules itself out for incorporation. The lowers both Cliff and I agree do not require adjustment if the shrouds are adjustable. In short there is nothing to add.

I have conducted tests of my one string system, and I am satisfied subject to further testing and refinement it will be of advantage to all, irrespective of ability. (Slightly biased view)

The system Cliff and Gavin are promoting has great merit, being cheaper than a one string system and it appears easier to set up. I do have concerns over the lateral compression when fitted to a Mk1 boat, but this can be negated by increasing the mechanical advantage of the pulley system attached directly to the shrouds from 2 to 1 to 5 to 1. However, this does up the overall cost. The only worry I have is what would be the result if both shroud and forestay adjusters are released inadvertently. The only drawback I can foresee is one of restoring initial settings.

A one string system will be more expensive to fit. However, it will not open Pandora's box to further evolution. It has only two control lines which, like Cliff's system, would only utilise existing cleats (where adjustable lowers are fitted). It should also provide all the non cost benefits Cliff has listed. One continuous control line adjusts the rig tension to the required setting. The second continuous control pulled one way increases rake, and pulled the other way reduces rake. Once the rig tension is set it should remain constant, until such time as the mast bends, either by the lower tension relaxing or kicker tension being increased. This means that the rig tension may not need adjusting and the only adjustment needed would be to pull the rig back up wind and forward downwind. It should Return to the starting point with the original rig tension restored; as long as the kicker is returned its starting tension.

I am of the opinion that the best route is to spend the next year testing out a one string system. Fitting a system with shrouds and forestay adjusted separately, is using old technology, when a popular (in other classes) modern system is slightly more expensive, but carries several advantages as well as doing everything the old technology does.

What is for certain is that continuing to race in high winds with slack rigging is not desirable, particularly on the sea with large waves. However, one has to accept that many fleets sail on lakes where the risks diminish significantly. I don't foresee any speed advantage being derived from any of the three options. I think it has to be judged on the grounds of safety, and convenience.

The 3 options are 1) most obviously, do nothing, 2) test out a cheaper dated system or 3) test out a more expensive modern system. Whatever is decided the Supernova will remain a top quality singlehander that is much admired.
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Re: Adjustable Shrouds on the Supernova

Postby IainWilson170 » Thu Aug 25, 2016 7:44 pm

I would think a one string system would address my point about the benefits to sailors of differing abilities. Depends on the cost though. One question we need to ask ourselves is will we eventually progress to a one string system whatever we decide now? if the answer is yes we may as well get on with testing/adopting it. Also it is obvious that modernising the boat and making it look great attracts new members to the fleet, not sure that sticking a pulley in the lower adjuster fits this bill.
What is the cost of a one string system merlin?
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Re: Adjustable Shrouds on the Supernova

Postby philipcoles » Thu Aug 25, 2016 8:41 pm

Being new to the Supernova this year and sailing in estuary / waves most of the time, anything that addresses the (alarmingly) slack rig would be welcome. The one string solution is attractive and this should be fully examined. Welcome the innovation and hope to attend a few meetings next year.
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Re: Adjustable Shrouds on the Supernova

Postby Merlin » Fri Aug 26, 2016 1:32 pm

Firstly to answer one question about the cost. I reused some pulleys, but from memory the cost was about £250.00, however I will check through what I used because I have refined the system.

I have posted a short poor quality video of the system on U tube, it should come up if you search for Supernova One String System. In essence there are 2 controls, green either rakes the rig forward or rig back, the cleats are situated either side of the mast. Ideally the rake back should be on port side and the rake forward on starboard side. The orange control line is for rig tension and is continuous, the cleats are on the inwhale.

If you cannot view it let me know.

Edit - The Video can be accessed at this URL https://www.youtube.com/watch?v=iG9bXv1Yqms- Pete1068
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Re: Adjustable Shrouds on the Supernova

Postby IainWilson170 » Fri Aug 26, 2016 3:13 pm

Just looked at the one string vid. Wow thats a lot of rope and blocks, kinda changes the simple appearance of the boat. I now think that I would like to see both systems on the dinghy park operating side by side to form an opinion.
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Re: Adjustable Shrouds on the Supernova

Postby PaulBloom166 » Tue Aug 30, 2016 10:22 am

I've read the document which has been emailed out but am unclear of using rake vs rig tension to depower, can anyone explain what the main difference are?
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Re: Adjustable Shrouds on the Supernova

Postby Tom1134 » Tue Aug 30, 2016 4:01 pm

Same here!

As well as a debate on whether to adopt the new rig we also need a full explanation of what actually details powers it. Rake or less tension or both. Better have the debate before the beer.
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Re: Adjustable Shrouds on the Supernova

Postby nhalstead » Wed Aug 31, 2016 6:52 am

I'm fine with the current forward and aft rig movement, so am not really much interested in a single string system. But the one thing that IS a problem is the ability to let the boom out properly once going downwind with the rig more upright. From my understanding the system devised by Gav and Cliff will achieve this (although as someone else pointed out the notes are somewhat contradictory). It will simply allow the leeward shroud to be slackened when the rig is upright.

I've been contemplating this for several years and have achieved no progress due to my failure to address one simple issue. That issue is - what happens when you tack (or gybe) having forgotten to tighten the leeward shroud? My best guess is that the mast breaks, or possibly rips the footplate off the foredeck - it could even rip the foredeck off! Has anyone with more engineering skill than me looked into this?

I've used such systems on other boats and they are a wonderful solution to the problem - but I've only used it on bigger boats with hog-stepped masts. I can assure everyone that, sooner or later, the unstayed tack or gybe will happen. It may not be often, but it will - and generally of course in the heat of competition.

I fervently hope that someone can put my mind at rest over this and if they can I'm all in favour!

Norman
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Re: Adjustable Shrouds on the Supernova

Postby CliffMilliner » Thu Sep 01, 2016 7:34 pm

Good to see the differing opinions here.

Q) Depowering the rig-

Raking the rig depowers the sail by lossening the shrouds due to the mast raking back. Loose shrouds depower due to allowing the mast to cant slightly to leeward, bend more, and also absorb the shock loads of gust. But this comes at a cost of more mast rake, so increased weather helm due to COE moving aft, making getting stuck in irons easier and a lower boom so hits the water sooner when dumping main sheet. Some people however really like the extra rake on windy days. I would argue they are mostly top fleet guys, not majority of sailors.

Adjustable shrouds, allow you to loosen just the shrouds( both at the same time) , but keep the same mast rake. So you get all the benefits of depowering the mast, but keep the rudder feel/boom hight the same. This favours sailors who like a more upright mast, and don't like weatherhelm. I think this would help most members, especially new guys.

Both of the above work well, it's a mater of how you like the boat to feel when your trying to depowering the rig.

Q) Ajustable forstay and shrouds.
Gav and I discussed at length the proposal to only allow adjustable shrouds, and fixed forstay and lowers, so effectively only allow 1 of the 3 adjustable. As we found we never adjusted the forstay once we had the shroud set up., but decided this may not be liked.

Q) Single string.
This is the most difficult decision to make. Single string systems are simple to use, but come at a cost in £££, complexity to rig, and look untidy. I personally feel this is not where the class should be going in the near term. What ever the decision, I think we all need to keep in mind we don't want to do anything that slows the growth of the class, so we need to consider what's best for the majority of the membership, not just the top of the fleet. but also we don't want to stifle the slow evolution of the class, we don't want a M1/M2 situation again.

Hope that helps... It a quite complex subject.
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Re: Adjustable Shrouds on the Supernova

Postby IainWilson170 » Wed Sep 14, 2016 4:23 pm

What was the verdict on this at the agm?
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Re: Adjustable Shrouds on the Supernova

Postby AlistairGlen » Mon Sep 26, 2016 1:03 pm

'Answer came there none'!
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Re: Adjustable Shrouds on the Supernova

Postby Chris1333 » Mon Sep 26, 2016 7:01 pm

Hi all

Apologies for the delay, as you can imagine this is a very complex area and the committee have been busy discussing various options.

We have approached Hartley Boats to discuss possible ways forward and they are currently considering (it has been the boat show this week).

We will confirm our decision as soon as we can.

Thanks to everyone for their comments on this.

Chris

Chairman Supernova class association
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