Stus-List C&C Polars Again

RANDY randy.stafford at comcast.net
Tue Sep 27 18:46:58 EDT 2016


Speed over ground - the SailTimer App uses GPS to calculate speed. And it's showing about 0.75 - 1.0 knots faster than my onboard transducer-based speed instrument. Since I trust GPS more, I'm now calibrating the onboard instrument to match the speed shown by the app. 

I scrubbed my bottom a few weeks ago but couldn't see to get the keel (murky marina water), so I'm sure it's not perfectly clean. 

Cheers, 
Randy 

----- Original Message -----

From: "Jeffrey Nelson via CnC-List" <cnc-list at cnc-list.com> 
To: "cnc-list" <cnc-list at cnc-list.com> 
Cc: "Jeffrey Nelson" <jhnelson24 at gmail.com> 
Sent: Tuesday, September 27, 2016 3:42:46 PM 
Subject: Re: Stus-List C&C Polars Again 



Add a dirty bottom at this time of year and they'd work for my boat too. :-) 
Are you using speed over ground or speed over water for your baseline speed? 
-- 
Cheers, 
Jeff Nelson 
Muir Caileag 
C&C 30 
Armdale Y.C. 
Halifax 

On 9/27/2016 6:24 PM, RANDY via CnC-List wrote: 



Those are a reasonable approximation but they're from a 30E, the European edition of the 30, which has a different design from my MK I (e.g. reverse transom, different interior, probably different displacement), and who knows what sails and what kind of prop etc. That boat is apparently fastest on a shallow broad reach, probably under spinnaker. 

Assuming I can get an accurate set of polars for my boat this year, they'll still show lower speeds than the boat's true potential, because I have old tired sails including an undersized main, and I have a fixed prop. Even so I'd like to get an accurate set of polars as a baseline to compare against when I have new sails and a folding prop, hopefully next year. Then hopefully I can sail the boat to its true speed potential. 

Cheers, 
Randy 

----- Original Message -----

From: "Bill Coleman" <coltrek at verizon.net> 
To: "RANDY" <randy.stafford at comcast.net> 
Sent: Tuesday, September 27, 2016 1:26:24 PM 
Subject: RE: Stus-List C&C Polars Again 



Can’t you just use the polars given on that site? They have a C&C 30 


	

Wind velocity 	

6kts 	

8kts 	

10kts 	

12kts 	

14kts 	

16kts 	

20kts 
	

Beat angles 	

45.5° 	

43.7° 	

43.3° 	

43.7° 	

43° 	

41.3° 	

40.5° 
	

Beat VMG 	

2.55 	

3.08 	

3.46 	

3.8 	

4.14 	

4.39 	

4.53 
	

52° 	

3.98 	

4.73 	

5.31 	

5.82 	

6.15 	

6.35 	

6.5 
	

60° 	

4.26 	

5.02 	

5.65 	

6.08 	

6.34 	

6.52 	

6.72 
	

75° 	

4.51 	

5.3 	

5.94 	

6.29 	

6.49 	

6.67 	

7.02 
	

90° 	

4.64 	

5.61 	

6.24 	

6.55 	

6.71 	

6.8 	

7.04 
	

110° 	

4.77 	

5.75 	

6.31 	

6.63 	

6.93 	

7.23 	

7.53 
	

120° 	

4.65 	

5.63 	

6.24 	

6.57 	

6.86 	

7.18 	

7.75 
	

135° 	

4.27 	

5.19 	

5.97 	

6.39 	

6.67 	

6.96 	

7.56 
	

150° 	

3.68 	

4.6 	

5.39 	

6.04 	

6.4 	

6.66 	

7.21 
	

Run VMG 	

3.19 	

3.99 	

4.69 	

5.33 	

5.92 	

6.31 	

6.83 
	

Gybe angles 	

148.1° 	

152.1° 	

153.5° 	

159.8° 	

180° 	

180° 	

180° 



Right? 




Regards, 



Bill Coleman 




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