#108891 - 06/03/07 10:05 AM
Re: Upwind speed (Question)
[Re: Rolf_Nilsen]
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Carpal Tunnel
Registered: 06/16/01
Posts: 9582
Loc: North-West Europe
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Everybody Quote:
any details on the spi halyard along the jib luff route? That is mighty interesting!
It is, but I'm already on the edge of what I can say in public. This guy wants to make an impression on the upcoming F16 Global Challenge and has tweaked out his boat to do exactly that. I think it is most wise to not elaborate on this setup till after the Global Challenge so he can make maximal use of his "invention". Afterward is a different matter of course !
But basically what I wanted to say with it is that F16 sailors still have some way to go to optimize the boats. And we should all be getting into that and progress the F16 performance just as the A-cat sailors have done with their boats (and are still doing).
Wouter
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Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
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#108892 - 06/03/07 10:12 AM
Re: Upwind speed (Question)
[Re: Wouter]
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Hull Flying, Snow Sliding....
Carpal Tunnel
Registered: 02/06/04
Posts: 3526
Loc: Looking for a Job, I got credi...
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Quote:
Everybody
Quote:
any details on the spi halyard along the jib luff route? That is mighty interesting!
It is, but I'm already on the edge of what I can say in public. This guy wants to make an impression on the upcoming F16 Global Challenge and has tweaked out his boat to do exactly that. I think it is most wise to not elaborate on this setup till after the Global Challenge so he can make maximal use of his "invention". Afterward is a different matter of course !
But basically what I wanted to say with it is that F16 sailors still have some way to go to optimize the boats. And we should all be getting into that and progress the F16 performance just as the A-cat sailors have done with their boats (and are still doing).
Wouter
Oh come on Wouter, if it's been in the dinghy park, it's public knowledge. I assume he (I assume it's a he) has just routed the halyard partly down the mast, then thru a block at the hounds, down the forestay to another block on the foestay by the podder and then to the cleat on the font beam.
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F16 - GBR 553 - SOLD I also talk sport here
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#108893 - 06/03/07 10:16 AM
Re: Upwind speed (Question)
[Re: scooby_simon]
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Carpal Tunnel
Registered: 06/16/01
Posts: 9582
Loc: North-West Europe
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Humm ! This is getting a little bit out of hand. I hope he will not be irritate at me for spilling the beans. Quote:
Won't you (potentially) overload the bow areas running all that tension down to the forestay first ?
No, because any tension put on the spi halyard in this situation will lower the tension in the forestay by the same amount. In effect, the load on the bows will remain unaffected. That is just the beauty of it.
But I won't elaborate any further at this time beyond the point that I think it is a very interesting development myself and that I'm quite thrilled to see the EU importer of F16's boats engage in such efforts to evolve the F16 design. (And there are other idea's being tested as well)
How many importers/agents do that ?
I think we can consider ourselfs lucky with F16 agents like that.
If any of you want to scoop on things like this on the shortest possible time frame then I guess you guys just have to come over for the F16 Global Challenge in 10 weeks time !
And be sure to stay on for the long distance race (REM-race) that directly follows our week of bouy racing. It will be great to see a fleet of F16's participating in this 100+ boat race. There will be a very strong F18 fleet there for this distance race and if we can get 15-20 F16's participating then that would be absolutely perfect.
Wouter
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Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
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#108894 - 06/03/07 10:21 AM
Re: Upwind speed (Question)
[Re: Wouter]
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Hull Flying, Snow Sliding....
Carpal Tunnel
Registered: 02/06/04
Posts: 3526
Loc: Looking for a Job, I got credi...
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Quote:
Humm ! This is getting a little bit out of hand. I hope he will not be irritate at me for spilling the beans.
Quote:
Won't you (potentially) overload the bow areas running all that tension down to the forestay first ?
No, because any tension put on the spi halyard in this situation will lower the tension in the forestay by the same amount. In effect, the load on the bows will remain unaffected. That is just the beauty of it.
Eh
Unloading the forestay how, if the Spi halyard is in some way replacing the forestay when the kite is up (I assume the forestay actually just sags a bit) then the load is INCREASING on the bows as the distance between the hounds (top end of the forestay) and the lower fixing (on the bows) is de-creasing, thus load is increasing.
You have totally lost me here Wouter.
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F16 - GBR 553 - SOLD I also talk sport here
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#108895 - 06/03/07 10:28 AM
Re: Upwind speed (Question)
[Re: scooby_simon]
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Carpal Tunnel
Registered: 06/16/01
Posts: 9582
Loc: North-West Europe
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Dear scooby,
There is an agreement in place that development and testing is done in a protected environment. This way the involved parties feel free to discuss these things in private among themselfs. Garanteeing this free discussion is important in advancing the F16 design. And the driving force under these development projects is achieving some gain in performance over competitors, even when only temporary. Such factors need to be nurtured, because without it sailors are less likely to do all the hard work and investments.
It is a balancing act but eventually we all benefit in the long run as nothing can be kept secret for long periods anyway.
Additionally, you guys can all try to work out a system yourself. Maybe we find the perfect setup afterwards when comparing all individual systems after the Global Challenge !
I know that I'm going to try and work out my own setup. I actually have to as my cleat/halyard situation is different from his requiring me to adjust the setup.
Good luck you all,
Wouter
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Wouter Hijink
Formula 16 NED 243 (one-off; homebuild)
The Netherlands
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#108896 - 06/03/07 10:34 AM
Re: Upwind speed (Question)
[Re: Wouter]
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Hull Flying, Snow Sliding....
Carpal Tunnel
Registered: 02/06/04
Posts: 3526
Loc: Looking for a Job, I got credi...
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I Understand that. But can you expalin how by adding extra load on the front of the boat you reduce the load at the front ? Quote:
Eh
Unloading the forestay how, if the Spi halyard is in some way replacing the forestay when the kite is up (I assume the forestay actually just sags a bit) then the load is INCREASING on the bows as the distance between the hounds (top end of the forestay) and the lower fixing (on the bows) is de-creasing, thus load is increasing.
You have totally lost me here Wouter.
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F16 - GBR 553 - SOLD I also talk sport here
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#108897 - 06/03/07 11:30 PM
Re: Upwind speed (Question)
[Re: scooby_simon]
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old hand
Registered: 10/18/05
Posts: 951
Loc: Brisbane, Queensland, Australi...
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Maybe a shock-cord take-up system is employed which pulls the loose halyard to the bridle, but when the halyard is tensioned it runs its normal course straight up the mast.
If it were running from beam to bridle and up the forestay the loads would be a bit strange...you'd think it would load up the bridle and unload the forestay, but then again, you are running downwind so the forestay/bridle isn't heavily loaded anyway.
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#108899 - 06/04/07 08:21 AM
Re: Upwind speed (Question)
[Re: Mark P]
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veteran
Registered: 02/25/05
Posts: 1382
Loc: Essex, UK
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Guys,
This approach to the spin halyard routing is not new. There were Shearwaters with spin halyards running down the forestay 20 odd years ago. The Shearwater was one of the very earliest adopters of the wing mast and some owners tried to improve the airflow by re-routing their jib and spin halyards.
There are still Shearwaters today with external spin halyards running down the mast so I guess that even after all this time the jury's still out on the benefits?
One of the best solutions I've seen is to go internal and exit at the front of the mast above the gooseneck. The halyard then drops down to a spring loaded block at the base of the mast, runs forward, round a turning block and then back to a spinlock on the beam. From there it's the usual route back to a block/ring and then forward through the chute.
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John Alani
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Stealth F16s GBR527 and GBR538
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#108900 - 06/04/07 08:22 AM
Re: Upwind speed (Question)
[Re: Mark P]
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old hand
Registered: 10/18/05
Posts: 951
Loc: Brisbane, Queensland, Australi...
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This is a possible line of reasoning for the conditions you described.
The lower weight of an A-class means less hull resistance (in general) and lower righting moment (in general).
Lower resistance directly influences speed at all points of sail.
Lower weight may also reduce their pitch radius of gyration (how easy/hard it is to rotate the boat in pitching) which has been shown to improve the performance of boats, particularly upwind.
Lower righting moment means that they can fly a hull with less pressure in the rig, which means they don't need as much draft in the sail (the sail is flatter in general), flatter sails have less drag and can also point higher. Both increase VMG.
A-classes also have less "stuff" dangling about in the wind creating drag. Items like spinnaker poles, chutes, bigger hulls and extra crew all increase the windage (drag from wind) of the boat, which is slower.
A-classes are lean, finely tuned, upwind dominating machines. In their condition, there is not much on the water that can touch them.
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