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Board » Technical Support » Mini 6.5 polars

Posted by Hirilondë Posts 48 Registered at 2010-02-22 12:50:31	2015-11-14 23:06:17 - Mini 6.5 polars
	I just logged into the Inhaca RTI Sprint to set up my morning back up DC for the start and noticed the polars for the present wind. I am in 15.6 kts. wind and the optimum TWA to weather is 34º? Unless they have done some drastic changes to the class I don't recall a Mini ever being able to sail much better than 45º TWA. In 2005 Rodney Johnstone's proto design was built for the 2007 Mini Transat. It was probably the most weatherly proto built and could just get to 45º TWA These are reaching boats designed specifically for the route from France to Brazil. Anyway, I suggest checking into this. Probably too late for this race, but 34º is unrealistic to keep.
Posted by kroppyer Posts 346 Registered at 2010-02-05 15:25:55	2015-11-14 23:39:37 - Re: Mini 6.5 polars
	Hi Hirilonde, We are aware that the mini 6.50 polar is not as realistic as can be in multiple ways. Partially because you pointed it out 2 years ago here. We try to be as realistic as we can (without getting wet), and there's a lot of places where we can improve. In the case of designing polars and updating them, we try to take the guesswork out of it more and more. We try our best to get reliable data to create a good polar. I'm not sure how the mini polar came to be. If we were to update the polar, my opinion would be that it has to be based on good data. In the absence of that data, there will be no update. Personally, I really like the mini 650 polar sol has. It might not be worthy of carrying the name "mini 6.5" because it doesn't represent the performance of a mini well enough, but it's a challenging polar that I enjoy very much. If this mismatch between polar and reality is a real issue, renaming the polar might be a solution. But apart from that, it would of course be nice to have a good, realistic mini 6.5 polar on sol. We need data for that (at least 40 points of high quality, if points are less reliable we need lots more points. The OD60v3 polar was designed using several thousands of datapoints). --- Last Edited by kroppyer at 2015-11-14 23:42:52 ---
Posted by Hirilondë Posts 48 Registered at 2010-02-22 12:50:31	2015-11-15 01:52:54 - Re: Mini 6.5 polars
	Thanks for the reply, again The Mini is a box rule, so there is no one polar and I have no data on any boat myself. I would think that rounding out the curve to weather to be a little more like a multi-hull would make SOL's polar at least a good bit closer to real. I am not so concerned about being an actual reflection, but the performance of this polar is just plain weird. In the mid range winds it is almost as if the boat had 2 head sails creating a dip in the curve. And I have never seen the dip of any polar at 40º TWA. Thanks for listening...........
Posted by bonknhoot Posts 97 Registered at 2013-08-06 21:35:15	2015-11-15 05:11:45 - Re: Mini 6.5 polars
	Hi Guys, While Qt crunches here's two further thoughts on the matter. 1/ two headsails is exactly how I always interpreted this polar, which has the merit of keeping you busy. 1a/ two downwind sails (a gennaker and an oversized symmetrical) also seems to be part of the wardrobe, for more HOT (hand on the tiller) sailing. 2/ there is a source against which we can compare our data. VR are running the Mini Transat at the moment and their polars are available on http://gwranking.forumactif.org/h10-outils-pour-vrtool. I'll do a comparison and report back. Clipping along
Posted by Hirilondë Posts 48 Registered at 2010-02-22 12:50:31	2015-11-15 08:18:49 - Re: Mini 6.5 polars
	Last I knew all a Mini had was a working jib, code 0, large and small spinnaker.
Posted by JB Posts 305 Registered at 2013-03-07 08:54:34	2015-11-17 12:53:06 - Re: Mini 6.5 polars
	From: http://minitransat650.com/leov/html/design.html "Sails : The number of approved sails carried on board must not exceed eight (8). This must include a storm jib of maximum area 4m2, reef able to 2.5m2, and a try sail of 5m2 maximum area of a fluorescent colour and a minimum weight of 340 g/m2. Material Sails (EXPECT BIG CHANGE IN 2008 RULES) * Mainsail : woven polyester, with windows of 0.2m2 maximum area.* Head sail : woven polyester and polyester film * (Head sails in 3DL are permitted but only in polyester -this was a ruling made in February 1997)* Spinnaker : nylon *Double film sails count as 2 sails. A wing mast of more than 2m2 in projected area counts as one sail, as well as any other wind propulsion system. See article I-11 for the sail number rule." Sail Fair.
Posted by Rod Posts 392 Registered at 2010-06-24 22:30:48	2015-11-17 19:21:22 - Re: Mini 6.5 polars
	Do you intend that we will have a choice of sails? --- And if we guess wrong, the sail will blow-out and be lost forever? Yours for greater realism!!!!!! Rod If it breaks, it's not strong enough--if it doesn't, it's too heavy.
Posted by JB Posts 305 Registered at 2013-03-07 08:54:34	2015-11-18 09:42:58 - Re: Mini 6.5 polars
	Viva Rod. Yes you can choose your sails for the race but, inside the actual J-23 paragraph Sail Rules (2015_-_OFFICIAL_TEXTS_-_MINI_RULES_(J_AND_S).pdf). If you made a bad sail/material choice and/or blew it under way, that’s it, you have to conform to it. Sail Fair.
Posted by JB Posts 305 Registered at 2013-03-07 08:54:34	2015-11-18 09:45:12 - Re: Mini 6.5 polars
	Have also a look on: argo 650 ficha.pdf , about the number and type of sails for the mini 6.50 class. Sail Fair.

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