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Demise of the Laser 4000

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salmon80 View Drop Down
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Post Options Post Options   Quote salmon80 Quote  Post ReplyReply Direct Link To This Post Topic: Demise of the Laser 4000
    Posted: 07 Jul 20 at 11:59pm
Originally posted by JimC

This too is interesting...
THE 23RD CHESAPEAKE SAILING YACHT SYMPOSIUM
ANNAPOLIS, MARYLAND, MARCH 2019
Science of the 470 Sailing Performance
Yutaka Masuyama, Kanazawa Institute of Technology, Kanazawa, Japan
Munehiko Ogihara, SANYODENKI AMERICA, Torrance CA, USA


http://vm2330.sgvps.net/~syrftest/images/library/20190319140724.pdf

not the first to tank test a 470, the greeks had a go in 2006 too.

stiffness is all wrong too for model versus full scale and the 470 is renowned for its softy spongy like nature 

All a bit of a waste of time really, 470's are small and cheap its better just to do full scale testing rather than waste money on models and tanks
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Post Options Post Options   Quote Sussex Lad Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 20 at 6:44am
Symmetric downwind on the sea?

It also rather depends what the following waves are doing, they are rarely dead square and they vary in size. It would be a dull old day if sailing the straight line was quicker. Just as well the uninteresting dead run that some refer to when extolling the tactical interest of the assy doesn't happen that often, not on the sea anyway.



Edited by Sussex Lad - 08 Jul 20 at 6:52am
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Mark Aged 42 View Drop Down
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Post Options Post Options   Quote Mark Aged 42 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 20 at 8:06am
And just to muddy the waters further for singehanders, Lasers go faster when sailing by the lee in extreme downwind angles.

Edited by Mark Aged 42 - 08 Jul 20 at 8:07am
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 20 at 8:15am
Doesn't really muddy the waters. Lasers sailing by the lee is just another demonstration that sailing dead downwind is slow.

Edited by JimC - 08 Jul 20 at 8:15am
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 20 at 8:42am
Originally posted by salmon80


Originally posted by JimC

This too is interesting...
THE 23RD CHESAPEAKE SAILING YACHT SYMPOSIUM
ANNAPOLIS, MARYLAND, MARCH 2019
Science of the 470 Sailing Performance
Yutaka Masuyama, Kanazawa Institute of Technology, Kanazawa, Japan
Munehiko Ogihara, SANYODENKI AMERICA, Torrance CA, USA


http://vm2330.sgvps.net/~syrftest/images/library/20190319140724.pdf

not the first to tank test a 470, the greeks had a go in 2006 too.
stiffness is all wrong too for model versus full scale and the 470 is renowned for its softy spongy like nature 
All a bit of a waste of time really, 470's are small and cheap its better just to do full scale testing rather than waste money on models and tanks

They did full scale testing for the resistance but model scale testing for other coefficients. I have tank tested models bigger than a full size 470 so it is possible given a large enough facility but I assume their university tank isn’t big enough for that. Regardless, it won’t be hugely off if they have accounted for Reynolds number scaling effects.
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 20 at 9:10am
In this context, I don’t think running square literally means at 180 to the wind, it means whether the apparent wind is aft (and therefore less than the true wind) or forward of the beam (in which case it is stronger than the true wind). If your boat has decent speed potential hotting up and sailing the extra distance is worth it. If the boat is speed limited it isn’t. The 470 doesn’t run at 180 but the apparent wind is still well aft of the beam on its best downwind VMG, therefore it’s doesn’t need a low drag (asymmetric) sail.
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Post Options Post Options   Quote Cirrus Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 20 at 9:47am
..........therefore it’s doesn’t need a low drag (asymmetric) sail.

Exactly.  And there are many 'asymetrics' that still don't really cut it.  Give the crews a ('permitted') option to goosewing the wretched sail and in many conditons and locations that is exactly what they would choose to do ...


Edited by Cirrus - 08 Jul 20 at 9:49am
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JimC View Drop Down
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 20 at 11:44am
But if you accept that no-one should actually be running square, then half the commonly made arguments for a pole kite disappear. There is of course no reason why a sprit kite can't be cut big full and baggy, indeed where windward/leewards are the course of choice they can be. Coupled to that is the undeniable fact that you can run a much larger sprit kite and much longer effective pole length for the same level of handling difficulty.

Then there's also the other reason why I abandoned the pole kite on my Cherub after a season. I simply got fed up with losing two places on every gybe mark...
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Post Options Post Options   Quote Guests Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 20 at 12:23pm
Very true, ease of handling is a big bonus compared to a pole kite.
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 08 Jul 20 at 3:11pm
Returning to the Alto earlier discussion, I really enjoyed that period of my sailing, not many other boats you can take a raw beginner out and get him/her to the front of the fleet. It hasn't completely failed, it's still out there, people buying and selling them, doing quite well on round island events etc despite having a good PYAG caning early on. (If you want to stop new boats failing this anachronism has to go, along with its class riven prejudices).

It's not perfect, they never seemed to have gotten the kite delivery system perfect and it's still a none wash through self baler, but as a fast man wife, light heavyweight, combo it certainly rivals the RS400, I'd buy another if a potential crew ever came onto my horizon.

I'd love to have been able to race it along with others to test the efficiency of the swinging pole and soaking low as against high and fast. At best it was a get out of jail card for the last bit of a long reach sailed perhaps too high and without wanting to go for another gybe.

I'm trying to wrestle the swinging system off my old V2 and give it a go on the Farr, reckon it would be excellent.

Edited by iGRF - 08 Jul 20 at 3:12pm
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