Does anyone have the polars for a C&C 33 MK II?
John on Enterprise
On Tuesday, September 27, 2016 12:58 PM, RANDY via CnC-List
<cnc-list@cnc-list.com> wrote:
No problem Bill.
Since we're back to this, I've appended the polar data (in CSV format) I got
from my SailTimer Wind Instrument and SailTimer App this past weekend, as
promised. Needless to say, I think this data is wrong, for reasons discussed
below. For example it shows I can reach hull speed close-hauled in 9 knots of
wind, but I'm slower than that on beam reach in the same wind. I don't think
either of those things is true.
,TWS
TWA,3,6,9,12,15,18,21
22.5,0.5,1.2,1.5,1.5,1.5,1.5,1.5
45.0,2.0,5.0,6.7,6.7,6.7,6.7,6.7
67.5,1.6,4.1,5.5,5.5,5.5,5.5,5.5
90.0,1.6,4.1,5.4,5.4,5.4,5.4,5.4
112.5,2.7,4.0,5.4,5.4,5.4,5.4,5.4
135.0,1.5,3.8,5.0,5.0,5.0,5.0,5.0
157.5,1.3,3.3,4.4,4.4,4.4,4.4,4.4
180.0,2.6,3.0,4.0,4.0,4.0,4.0,4.0
Now, why is this data wrong. First, it was the first time I'd used the
SailTimer App in anger and it wasn't a controlled experiment in polar learning
(the app lets you toggle polar learning on and off, and I wasn't careful about
when it was on). Second, this data was collected in a variety of wind
conditions and sail configurations. Friday afternoon it was blowing 20 gusting
35 and I was sailing under double-reefed main only because my mom was aboard
with only one other of my regular crew and they were nervous in that wind
strength. Saturday and Sunday I was in a two-day regatta in very light and
fickle air under full main, 155% genoa, and sometimes even a staysail. Because
I was preoccupied with racing and adjusting sails constantly, I wasn't paying
attention to the app and accurate polar learning.
The app must have some kind of algorithm to interpolate / extrapolate boat
speeds in wind speeds and angles that it hasn't observed, because I can
guarantee I didn't hit every combination of TWS/TWA in the above data over the
weekend. But this gives an example of what the instrument and app can do.
Before the season ends, I'd like to get back out and do a controlled experiment
- a new data set under main and 155 in say 12 knots, through every TWA,
toggling learning on and off at the right times.
Cheers,Randy
From: "Bill Coleman via CnC-List" <cnc-list@cnc-list.com>
To: "cnc-list" <cnc-list@cnc-list.com>
Cc: "Bill Coleman" <colt...@verizon.net>
Sent: Tuesday, September 27, 2016 8:33:06 AM
Subject: Re: Stus-List C&C Polars Again
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That is a sweet page, Thanks for Sharing.I was able to make a .csv and import
it into the e-95, (I usedthe C&C38 Polars). Unfortunately it will probably be
next spring B4 I seewhat it does for my Dynamic Vectors/Laylines. Bill
ColemanC&C 39 Erie, PA From: CnC-List[mailto:cnc-list-boun...@cnc-list.com] On
Behalf Of RANDY via CnC-List
Sent: Thursday, September 22, 2016 12:28 PM
To: cnc-list
Cc: RANDY
Subject: Stus-List C&C Polars Again Listers- Justwanted to share a site I saw
with polars for a few different C&Cmodels:
http://jieter.github.io/orc-data/site/ Ifyou look at the list of boats in the
left-hand column (or search for"C&C" on the page), you'll see the following
models:*C&C 30 (this is the new one-design version, I can tell from the boat
speedsdownwind - it planes :)*C&C 30E (this is the European edition of the C&C
30, apparently built& sold 1977-1982)*C&C 37*C&C 38*C&C 110*C&C 115Justclick on
one of those boats and you'll see its polar diagram and polar table. I realize
that polars are very boat-specific and sail-specific,but at least here are some
data points. For example the other week I tooka couple hundred pounds of stuff
off my boat, emptied the tanks, and cleanedthe bottom, and I think it made a
difference in light air. But my sailsare old and tired, so I know my boat's
polars will change again when I get newsails and a folding prop.
Forus software developers on the list, it almost looks like thisguy
@Jietermanis might have github-hosted software to create polardiagrams from
user-supplied polar table CSVs. I've tweeted him for moreinformation.
Lastnight I got my SailTimer Wind Instrument installed at the masthead, so when
Igo out tomorrow afternoon the SailTimer App will be able to learn one
polarcurve for my boat, assuming I'm optimally trimmed on all points of sail.
The wind is now forecast to be blowing 15 gusting 20, so hopefully I canget
polar data with the same sails I race under (full main and 155 genoa,
nospinnaker). If the wind gets much stronger I might have to reduce sail,
sothe polar data wouldn't be representative of my normal racing configuration.
BestRegards,RandyStaffordS/VGrenadineC&C30-1 #7KenCaryl, CO
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what we do, please help us pay for our costs by donating. All Contributions are
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