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tingeling 
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Joined: 27 December 2006 Location: Norway Status: Offline Points: 148 |
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 Topic: Polar diagramsPosted: 28 March 2008 at 21:09 |
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I have been searching this and other forums for polardiagrams for my Hanse 400e. I have found diagrams for 430, 370 and eventually 400. But looking closer at them I find them to be quite similar. Strange, or do they just copy the one they had? The only slight difference is on a tight beat, otherwise they all seem to reach 10 knots on a broad reach, the 400 fastes of the the 3?.
 And the 370 as fast as the 430! This is when looking at 120 deg at 20 knot wind.
   Edited by tingeling - 29 March 2008 at 15:58 |
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Peter-Blake
Admiral of the Fleet 
Joined: 04 March 2008 Status: Offline Points: 2471 |
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Posted: 29 March 2008 at 12:57 |
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I think the diagrams show the right boats.
The reason is simple for me:
I.E:
cwl of 370 is 10,05m
cwl of 400 is 10,80m
the theoretical max. boat speed will be:
for 370 2,43 * sqrt 10,05 = 7,70 kn
for 400 2,43 * sqrt 10,80 = 7,98 kn
I hope sqrt is the correct translation for "Quadratwurzel" in german
Yor see, the speed difference between both boat is quite small. A better set sail on the 370 and it will be faster than the 400 ;-)
If you look in the diagram you will find this small diffrence, i think.
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Blake 370
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panos
Admiral 
Joined: 02 March 2008 Status: Offline Points: 1939 |
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Posted: 29 March 2008 at 13:39 |
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from the IMS racing certificates which I found at www.bryggan.net (Hanse dealer) following is obvious :
The published polars for the boats use spinnakers over about 95 ° of true wind so it doesn't matter if they have 105% or 140% simply because they don't use the jib/genoa. They use the spi.
 The values for 105% jib and 140% genoa are the same for true wind over 15 knots because anyway you "reef" the 140% genoa (I mean you change to a #3 = 105%)
 The speed difference of 370 and 400 are (for 60° true wind direction and 10 knots) as follows :
370 with 105% 515 sec/mile=> speed=3600/515= 6.99 knots
370 with 140% 501 sec/mile=> speed=3600/501=7.18 knots
400 with 105% 498 sec/mile=> speed=3600/498=7.23 knots
400 with 140% 485 sec/mile=> speed=3600/485=7.42 knots
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Panos
Hanse 630e - selling her - |
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tingeling
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Joined: 27 December 2006 Location: Norway Status: Offline Points: 148 |
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Posted: 29 March 2008 at 13:53 |
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Thank you for the clarification on the spinaker from the IMS certificate. Normally they will draw the diagram with a new line if that was the case, because the speed at ex. 95 deg. will probably not be the same with the spin and the genoa.
Anyway...I am still confused that, despite the wl speed calculations, at 120 deg / 20 knots wind the 400 shows 10,3 knots, the 370 10 knots and the 430 also 10 knots......in that case the 430 diagram must be wrong....or the two other ones.
I am a little bit wiser, but still wondering.
Tingeling
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panos
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Joined: 02 March 2008 Status: Offline Points: 1939 |
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Posted: 29 March 2008 at 14:30 |
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for 120°,20knots true wind :
hanse 370 374.6 sec/mile =>speed= 9.61 knots
hanse 400 364.2 => 9.88
hanse 400e 361.8 => 9.95
hanse 470e 347.0 => 10.38
didn't find certificate for 430,540e or 630e for which I have special interest. Anybody seen one?
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Panos
Hanse 630e - selling her - |
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tingeling
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Joined: 27 December 2006 Location: Norway Status: Offline Points: 148 |
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Posted: 29 March 2008 at 15:23 |
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So...I guess one should make one self an individual polardiagram based on actual sails, weight, propeller and soforth....
By the way, congratulations with your wedding...best of luck.
tingeling
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panos
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Posted: 29 March 2008 at 18:47 |
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thanks tingeling,
the most important factors to speed are : the propeller to be folding, the surface of the hull which must be perfectly smooth and clean, the sails and sail trim, the crew position , the things you carry on board (actually what you don't carry) and how you drive. The hull shape and the boat length come second. A racing team with a carefully prepared boat and good sails will sail faster than bigger and better boats if they are not setup properly and not sailed correctly .
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Panos
Hanse 630e - selling her - |
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sulutime
Commander
Joined: 06 April 2006 Status: Offline Points: 96 |
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Posted: 30 March 2008 at 14:18 |
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I don't want to be unpolite to anyone but even if Panos is absolutelly correct saying that any well trimmed and steered boat can kick almost any big badly sailed ass, the polars are not built by testing the boats , in wich case they could be tainted by crew, sail shape, water conditions or hull conditions, but simply calculated with VPP by the design team (J&V) so they are based on clean numbers and simply reflect a better balanced project, or maybe an higher sail to displacement ratio, or any other parameter that the VPP takes into account for his predictions. For a broad view on how many parameters and ratios come into such play you can check at http://www.sailingusa.info/design_winds.htm.
Fabrizio Edited by sulutime - 30 March 2008 at 16:02 |
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Fabrizio H400e#127 Roma ITALY
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colincooper
Rear Admiral 
Joined: 23 October 2005 Location: United Kingdom Status: Offline Points: 562 |
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Posted: 30 March 2008 at 14:44 |
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It would be great if anyone has a more typical polar for any of the boats. Presumambly the official one is more aimed at selling Hanses than realistic figures. I'm not a racer and it would be nice to know how close to "optimum" we sail. Has anyone plotted any?
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Colin (owner of Hilde - a 370)
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sulutime
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Joined: 06 April 2006 Status: Offline Points: 96 |
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Posted: 30 March 2008 at 16:01 |
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Sorry again Colin, but the purpose of a "pure" or, more plainly, of a "calculated" polar, is exactly to give a theoretical target to strive for when trimming and steering a boat. The polar shows the optimum and your own diagram shows how closely you are sailing to theoretical optimum. Personal polars (at least I think that's what you mean with typical) are only useful against designed polar, otherwise they only compare crew and boat performance. But for that, sailors invented regattas that are much more fun!!!
Fabrizio Edited by sulutime - 30 March 2008 at 16:04 |
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Fabrizio H400e#127 Roma ITALY
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