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Re: Uni spin hoist [Re: Smiths_Cat] #228191
02/04/11 04:25 PM
02/04/11 04:25 PM
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West coast of Norway
Rolf_Nilsen Offline

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I think the mid girth rule is there to prevent the sails from being used upwind. Another handicap/rating rule standing in the way of development..

I have not tried the "pump action" solution, but I have some ideas I would like to test. Being able to set and retrieve reasonably fast with one hand.. Hmm.

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Re: Uni spin hoist [Re: Smiths_Cat] #228196
02/04/11 05:51 PM
02/04/11 05:51 PM

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Originally Posted by Smiths_Cat
Hi Rolf,

I think there are two problems: The first is the mid-girth rule. If you want to have a furling sail, you have the leading edge more straight and than the rule makes the trailing edge too curved to get enough tension on it to get a good shape. The other "problem" is that a furling sail will have a flatter cut, but I am not sure if this is really a drawback, especially if you save 5 s during hoisting and taking down.
For me, the real development stopper is the mid-girth rule. Remove it and after a couple of years we will see much better down wind sails.

Cheers,

Klaus

On a single hander which is what we're discussing here, I have little doubt a flatter kite would be faster. I'm adding complication here for the sake of internet conversation but could we add short "air batten" parallel to the luff to support the oversize leach?

Re: Uni spin hoist [Re: ] #228274
02/06/11 01:57 PM
02/06/11 01:57 PM
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West coast of Norway
Rolf_Nilsen Offline

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The question is really:

1: Is flatter faster on a singlehander

2: Can we make such a sail work with roller furling

My opinion:
No 2: Of course we can

No 1: I dont know.

Last edited by Rolf_Nilsen; 02/06/11 02:01 PM.
Re: Uni spin hoist [Re: Smiths_Cat] #228276
02/06/11 03:26 PM
02/06/11 03:26 PM
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DanTnz Offline
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My boat doesn't luff either. I find that raising the sail is very quick, especially using the two line system where the spin is already partially out of the chute before rounding the mark. Although obviously you still have to turn down off the wind to raise for much longer than a 2-up boat. But I think it is lowering the spin that soaks up the most and loss of speed. Also, this is where you have to steer a little bit, because you have the mark rounding as a target, where at the top mark you have an open course. If I get it right I'll sheet in the main to round the mark without using the rudder, more complicated if gybing round as well.

So, I don't think the pump up system will help all that much, what you need is a kind of spring loaded retrieval system!

For the same reasons I can't see how a furler will help that much, it's still going to take a couple of operations to stow away the sail (furl and then retrieve). But I guess it could allow you to carry the sail right to the mark though, so worth investigating if someone has the time.

Originally Posted by Smiths_Cat


On non trapezing single hander dinghies with spi, I used to put the tiller extension in the hollow of the knee to helm the boat or simply step on it to fix it. Of course on a cat with its long tiller extension it is not possible, but maybe a device to fix the tiller could already help.
By the way my boat will not luff, if the traveller is dropped. Hence the boat runs straight on a deep course.

Cheers,

Klaus

Re: Uni spin hoist [Re: DanTnz] #228278
02/06/11 03:50 PM
02/06/11 03:50 PM

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My theory with the furler is that it lets you hoist and drop the sail at less critical times with respect points on the course and as a result protect your lanes.

Re: Uni spin hoist [Re: Rolf_Nilsen] #228285
02/06/11 08:07 PM
02/06/11 08:07 PM
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scooby_simon Offline
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Originally Posted by Rolf_Nilsen
I think the mid girth rule is there to prevent the sails from being used upwind. Another handicap/rating rule standing in the way of development..



Not a handicap or rating rule; the girth rule generally defines what a spi is; Girth <75% it's a Jib; >75% it's a Spi.


F16 - GBR 553 - SOLD

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Re: Uni spin hoist [Re: scooby_simon] #228296
02/07/11 12:39 AM
02/07/11 12:39 AM
Joined: May 2003
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West coast of Norway
Rolf_Nilsen Offline

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Originally Posted by scooby_simon
Originally Posted by Rolf_Nilsen
I think the mid girth rule is there to prevent the sails from being used upwind. Another handicap/rating rule standing in the way of development..



Not a handicap or rating rule; the girth rule generally defines what a spi is; Girth <75% it's a Jib; >75% it's a Spi.


That is semantics. Point still stands.

Re: Uni spin hoist [Re: Rolf_Nilsen] #228356
02/08/11 04:34 AM
02/08/11 04:34 AM
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Hamburg
Smiths_Cat Offline
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Originally Posted by Rolf_Nilsen
The question is really:

1: Is flatter faster on a singlehander

2: Can we make such a sail work with roller furling


I guess that question number one should be:
Is flatter slower on a single hander?

If not and furling is possible, then try it.

By the way, do the VX40 drop the furled spi once it is up?

Quote
I'm adding complication here for the sake of internet conversation but could we add short "air batten" parallel to the luff to support the oversize leach?

From a rule's point of view I don't know. From an aerodynamic point it will help to stabilize. What about horizontal inflated battens? I think it will be more efficient in stabilizing.

Cheers,

Klaus

Re: Uni spin hoist [Re: Smiths_Cat] #228358
02/08/11 04:57 AM
02/08/11 04:57 AM
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What happens when you pitchpole and you have to furl it?
Wouldn't that be a lot harder then pulling it into a regular snuffer?, and would you really want a wet furled sail that high up?

Re: Uni spin hoist [Re: Tony_F18] #228359
02/08/11 05:16 AM
02/08/11 05:16 AM
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Melbourne, Australia
Tornado_ALIVE Offline
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VX40s raise and lower their screacher in between downwinds to reduce windage. It is a lot slower to raise/lower and unfurl/furl than it is to set and drop in a chute.

At the top and bottom mark, you olny want to come in once to deal with the kite. Not furl and drop it later.... You should be on the wire and concentrating on your upwind.

Also, dropping a furled screacher is normally the job of more than one person. One drops the halyard whilst the other gathers the kite. Boats that do this tend to have netting in front of the front beam to give the crew access. You also need somewhere to lash the screacher down. So, a screacher that needs to be dropped is a no go for a small OTB craft. Keeping it up = far to much windage and weight aloft.


Re: Uni spin hoist [Re: Tornado_ALIVE] #228363
02/08/11 08:49 AM
02/08/11 08:49 AM
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Hamburg
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Originally Posted by Tornado_ALIVE
VX40s raise and lower their screacher in between downwinds to reduce windage. It is a lot slower to raise/lower and unfurl/furl than it is to set and drop in a chute.

At the top and bottom mark, you olny want to come in once to deal with the kite. Not furl and drop it later.... You should be on the wire and concentrating on your upwind.

Also, dropping a furled screacher is normally the job of more than one person. One drops the halyard whilst the other gathers the kite. Boats that do this tend to have netting in front of the front beam to give the crew access. You also need somewhere to lash the screacher down. So, a screacher that needs to be dropped is a no go for a small OTB craft. Keeping it up = far to much windage and weight aloft.


Keep it up. It is not so much more windage as many think. A midpole snuffer adds drag as well. It is more weight up, but overall less weight than a snuffer. Unfurling is much faster than hoisting and furling is faster than dropping, espicially in big waves. I say this because my boat is fitted with a hooter, and I sail the boat with and without the hooter, so I can tell. I am not saying it is faster, but it is certainly not so worse not to try it (if furling is possible with the mid girth rule shaped sails).

After pitchpole/capsize you have to pull a line, pretty much as with a spi, but again it is faster. Righting requires for my 70kg to drop the wet sail and hoist once it is up. I think that with 80kg it would be a problem at all.

Hopefully I can once sail against a comparable boat to see how much of difference between spi and hooter is.

Cheers,

Klaus

Re: Uni spin hoist [Re: Smiths_Cat] #228368
02/08/11 11:01 AM
02/08/11 11:01 AM
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West coast of Norway
Rolf_Nilsen Offline

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That would be very interesting! Doing some two boat testing, swapping skippers when sailing one up!

Care to make an educated guess on the difference in drag, considering the turbulent flow at the waters surface?

Re: Uni spin hoist [Re: Rolf_Nilsen] #228387
02/08/11 03:17 PM
02/08/11 03:17 PM
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Posts: 69
Live in Germany, House in UK, ...
DanTnz Offline
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It would be great if someone tried this out. I can't help thinking though, that a spin that satisfies the mid-girth rule, even if you could furl it, is not going to roll up into a neat package. So probably it will be more 'draggy' than a furled hooter type sail.

Inflatable battens would help (to meet the rule and furl), but from the ones I've looked up, you either get permanently inflated (no furling) or inflated/deflated from a compressor or bottle. Which I'm pretty sure would breach external power rules from ISAF, which we all race under.

I really hope someone has a go at making work.

Re: Uni spin hoist [Re: DanTnz] #228389
02/08/11 03:41 PM
02/08/11 03:41 PM
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Daytona Beach Florida
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Is the ideal a 1 handed drop without the spin ending up in the water or under the boat?
Could you do this with a system that uncleated the spin halyard as you pulled the takedown line but reengaged the spin halyard cleat(or something that would temp lock the halyard and keep tension for a controled drop) when you were no longer pulling. This could be an automatic type device or something that could be engaged with your foot.

Last edited by orphan; 02/08/11 03:44 PM.
Re: Uni spin hoist [Re: orphan] #228392
02/08/11 04:11 PM
02/08/11 04:11 PM
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Live in Germany, House in UK, ...
DanTnz Offline
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Not sure that would achieve the right result. With a the two line system, trawling the spin isn't an issue. I had a single line on an older boat (not F16) and I don't think a clutch type system to keep tension on would have helped. You just want the sail away as fast as possible. You really want some way of speeding up retrieval rather than introducing more friction. The guys that use single line might have something to say though.

Re: Uni spin hoist [Re: DanTnz] #228393
02/08/11 04:12 PM
02/08/11 04:12 PM
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Originally Posted by DanTnz
It would be great if someone tried this out. I can't help thinking though, that a spin that satisfies the mid-girth rule, even if you could furl it, is not going to roll up into a neat package.


Scarecrow hit upon the solution earlier, have a look at http://www.facnor.com/uk/products/asym_spi_furlers/default.asp which sort of explains it a little.

Nothing very fancy just use a standard furling drum with D12 as the furling line and note the very neat mod of putting a short line to the centre luff edge of the sail, it pulls the centre of the sail in before the ends, it just a matter of adjusting that length to get the smallest tightest roll on the D12.

Re: Uni spin hoist [Re: waynemarlow] #228394
02/08/11 04:38 PM
02/08/11 04:38 PM
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MERRITTISLAND, FL
Matt M Offline
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Originally Posted by waynemarlow
Originally Posted by DanTnz
It would be great if someone tried this out. I can't help thinking though, that a spin that satisfies the mid-girth rule, even if you could furl it, is not going to roll up into a neat package.


Scarecrow hit upon the solution earlier, have a look at http://www.facnor.com/uk/products/asym_spi_furlers/default.asp which sort of explains it a little.

Nothing very fancy just use a standard furling drum with D12 as the furling line and note the very neat mod of putting a short line to the centre luff edge of the sail, it pulls the centre of the sail in before the ends, it just a matter of adjusting that length to get the smallest tightest roll on the D12.


Problem 1 - Even if you rolled up a perfectly flat hooter, it would have a very significant diameter. All that is up in as drag and in the air you want to be clean as it hits your driving sails. A mid pole snuffer system is tucked down where there is already disturbed air and quite a bit of serious testing in the Tornados showed it added negligible drag to the platform.

The advantage is that they are nearly self deploying. My experience with roller furling on other boats, it is likely to be as difficult to even more difficult to roll up. Either way for the 1 up guy 2 hands are needed to do it fast.

On the very few times I have seen them used on cats they appeared essentially non-competitive. There were other problems and issues, so a true comparison was not had. Logically it just doesn’t to appear that there is enough apparent wind generated to make a hooter perform better than a spin. We have already seen where super flat spin cuts are just not as effective as some others across the range of conditions down wind. For the odd condition or race like super light air where you can have a huge jib effect, or beam reaching they would be great. Upwind - downwind give me spin.

Re: Uni spin hoist [Re: Matt M] #228395
02/08/11 04:49 PM
02/08/11 04:49 PM
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For the time being I've decided to stay with the stock system with one change. I've added a turning block on the front cross bar so that I can retrieve the spin while looking forward. Addition of the turning block allows me a little better posture and body mechanics since I'm not twisted at the waist.


Pete Pollard
Blade 702

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Re: Uni spin hoist [Re: Matt M] #228424
02/09/11 10:00 AM
02/09/11 10:00 AM
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Quote
My experience with roller furling on other boats, it is likely to be as difficult to even more difficult to roll up. Either way for the 1 up guy 2 hands are needed to do it fast.

Add a spring between spi pole attachment and furler so that the furler drum stands upright. It is much easier to furl than to drop a spi. I gave the furling line some extra length and knot it to the rear beam. So I can furl the sail from the rear end of the boat. Gives you an extra good feeling in strong wind/wave situation, where on usual spi boats you have to go close to the mast. Two or three velcro strips are stiched on the sail where the sheet is attached. If fully furled, the velcro stripes keep the sail furled and you don't need a cleat. It is a very simple system, which can be rigged in one or two minutes.

Cheers,

Klaus

Re: Uni spin hoist [Re: Matt M] #228425
02/09/11 10:26 AM
02/09/11 10:26 AM
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All,

One major problem that no one has addressed yet is UPPER BODY STRENGTH! All these furlers, etc, still require 2 hands and then you have to get it down and on the boat (windage) wasting yet more boat lengths in a race. Furlers are for cruisers, IMO.

If I can say this on the forum, I had a very slick and easy system for retrieval on my F17. I could outperform 99.9% of the singlehanded spin sailors out there in the hoist and drop. I have pics somewhere on my computer if anyone would like to view. The 2 line systems talked about simply means you have to do one more movement again wasting valuable boatlengths without the kite up and sailing. Don't ask me how I know!

BC wink


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