Facebook

Login

Support Sailonline

If you haven't already - join the SAILONLINE YACHT CLUB!

Please also consider making a donation - all amounts are greatly appreciated!

Board » General Discussion » Real Life Honesty Race question

Page: Previous 1 2 3 4 Next

Posted by
NOR_Jawik


Users avatar

Posts
70
Registered at
2008-08-31 20:55:18
2011-04-14 12:04:54 - Re: Real Life Honesty Race question
Gilles said @ 2011-04-14 08:27:29:
Am I crazy?
No you are not. Fix course on Lat/Lon and no rumbline. I like it.
Posted by
BER_Baggus


Users avatar

Posts
70
Registered at
2008-12-26 18:46:10
2011-04-14 14:58:57 - Re: Real Life Honesty Race question
@Gilles & 76 - to be honest, the course is probably too short, only a few hours long. What I was after is what wind direction would be best for our polars. I'll see if I can all the GPS coordinates.
Posted by
76Trombones


Users avatar

Posts
362
Registered at
2009-08-03 18:04:56
2011-04-14 15:15:21 - Re: Real Life Honesty Race question
It's a good exercise! It's not the same as ocean-racing routing, but the tools are similar. Even without shifts and predictors and gribs and such, just identifying favourable prevailing wind conditions is a useful trick.

Totally doable with a spreadsheet. To make life easier for such things it's helpful to fill the area between VMGs (and any other hollows) so that you don't need to worry about tacking.
Posted by
BER_Baggus


Users avatar

Posts
70
Registered at
2008-12-26 18:46:10
2011-04-14 20:45:46 - Re: Real Life Honesty Race question
It's totally doable with a spreadsheet, assuming someone has that spreadsheet...... ;-)

The routing software is good, but it would only show you the optimum course for the forecast winds. I want too see what the best wind direction would be so that when, probably in 4 months time, it actually blows from that direction, we can make the best time. If that makes sense.
Posted by
Smo


Users avatar

Posts
80
Registered at
2009-05-02 21:49:04
2011-04-15 06:03:52 - Re: Real Life Honesty Race question
Should be quite obvious on just cheking wx no need for routers more tricky to get crew there in right time. And good sailing makes it.

--- Last Edited by Smo Smo at 2011-04-15 06:05:01 ---
Posted by
76Trombones


Users avatar

Posts
362
Registered at
2009-08-03 18:04:56
2011-04-15 19:57:47 - Re: Real Life Honesty Race question
I was going to show how to do this just with pen and paper, but here's an example spreadsheet. Change the leg angles and lengths. This is both clumsier and more complicated than necessary, but maybe can tell what is going on.

;-)
Attachments
Posted by
A2


Users avatar

Posts
347
Registered at
2009-10-26 00:39:42
2011-04-15 20:15:00 - Re: Real Life Honesty Race question
I am quite interested in All pen & paper solutions to the various sailing conundrums that encompass navigational exercises.

Please show your work :)

P.S.

When I open the .xls file in NeoOffice I get get a series of #ADDIN? errors for the Spline computation in the field as well as the final Best TWD & Fastest Time



--- Last Edited by Hubert Bonisseur at 2011-04-15 20:22:53 ---
None so blind
Posted by
76Trombones


Users avatar

Posts
362
Registered at
2009-08-03 18:04:56
2011-04-15 20:33:38 - Re: Real Life Honesty Race question
In words:

Convert your polar from knots to minutes/nm. For each leg, multiply the polar by the leg length and transfer to a plot using your dividers. The curve for each leg is added to the one preceding it. The resulting plot reads time, so your best TWD is the minimum.

Here is the data used in the spreadsheet example - the fastest angle in 12kt wind is ~214 degrees.

Course Leg 1 Leg 2 Leg 3 Leg 4
CC 0 45 270 130
NM 3 2 4 5


1/4 Ton 6 8 10 12 14 16 20
52 4.41 5.21 5.75 6.06 6.23 6.34 6.45
60 4.70 5.48 5.97 6.28 6.50 6.62 6.75
75 4.98 5.85 6.33 6.63 6.77 7.01 7.23
90 5.24 6.01 6.48 6.85 7.13 7.27 7.59
110 5.03 5.82 6.32 6.75 7.14 7.55 8.23
120 4.74 5.60 6.16 6.59 6.99 7.40 8.38
135 4.15 5.10 5.80 6.26 6.67 7.05 7.93
150 3.51 4.47 5.25 5.86 6.30 6.68 7.43

Bangle 43.4 42.0 40.4 40.9 40.0 39.3 39.4
BVMG 2.87 3.48 3.87 4.13 4.28 4.38 4.46

Rangle 146.6 152.9 161.6 167.0 172.9 174.7 175.2
RVMG 3.04 3.87 4.62 5.27 5.81 6.22 6.93
Posted by
76Trombones


Users avatar

Posts
362
Registered at
2009-08-03 18:04:56
2011-04-15 20:42:54 - Re: Real Life Honesty Race question
When I open the .xls file in NeoOffice I get get a series of #ADDIN? errors for the Spline computation in the field as well as the final Best TWD & Fastest Time
-

Yes the posted example uses a plugin for the interpolation functions and I don't think OpenOffice handles it correctly. Hmm...

There's a cubic spline function posted at oooforum.org. Very much worth looking into for sailing spreadsheets. I used a second function to find the minimum, but there areother ways to do that.
Posted by
Rod


Users avatar

Posts
392
Registered at
2010-06-24 22:30:48
2011-04-15 20:49:32 - Re: Real Life Honesty Race question
Duuuuh!!! Now I'm feeling stupid! I even taught coastal navigation for a while in the Navy but I do not have any idea what would be needed to get any info out of your spreadsheet. Hands up! How many SOLers know how to do this?
Sorry 76T, but its got to be simpler than that to help ME.
If it breaks, it's not strong enough--if it doesn't, it's too heavy.

Page: Previous 1 2 3 4 Next

Please login to post a reply.

Races

Next Race: 00d 00h 00m

Current Races:

Chesapeake and Potomac TIMED Race 2026

Welcome to the Chesapeake Bay, the sailing capital of the United States. Feast on Maryland crab cakes or crabs seasoned with Old Bay spice before sailing down the Bay aboard a Formula 18 catamaran on a 128 nm course that will take you up the Potomac River finishing at Quantico, Virginia. This is a TIMEDrace so you may RE-REGISTER HEREto try again after finishing a run. You will have two weeks to test your skill and decision making after the race opens.
Race #2032
INFOby brainaid.de
Formula 18 catamaran Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
TRQ2 - TRCH - SYC
RACE CLOSE: Saturday,
23 May at 23:00 UTC
Race starts: May 10th 12:00 Registration will open soon
▶ Flash
GO TO RACE

Tobruk to Iskenderun 2026

Welcome to the fourth of our nine races across the length and breadth of the Magical Mediterranean Sea, and the second that is not in partnership with a real-life event, this time for good reason, which we won’t get into here. From Tobruk to Iskenderun it’s 670nm in length, with the added complication that the island of Cyprus will be in your way. Hoping, possibly forlornly, for plenty of downwind sailing, we’ll take the Lagoon 55 for the voyage!
Race #1976
INFO by brainaid.de
Lagoon 55 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: MED - SYC
Race starts: May 05th 15:00 Registration Open!

▶ Flash
GO TO RACE

Tasmania to Kamchatka 2026

Welcome to yet another all-new route. Tasmania to Kamchatka, part of our Ocean Championship and also the third leg of the ROW (Round the Old World) series. Be aware of the obstacles on the way, likely to split the fleet. It's like X:mas to X:mas, crossing the same waters, navigating the same archipelagos. This second race of OCQ2 2026 will be sailed in our revised 'version 2' Imoca 60 Foil. Race #2031
INFO by brainaid.de
Imoca 60 Foil v2 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ2 - ROW - OCCH - SYC
Race starts: May 04th 11:00 Registration Open!
▶ Flash
GO TO RACE

Go to race archive

SYC Ranking

  1. Sailonline Yacht Club Member WRmirekd
  2. Sailonline Yacht Club Member CriticalHippo
  3. Sailonline Yacht Club Member rumskib
  4. Sailonline Yacht Club Member Panpyc
  5. Sailonline Yacht Club Member rafa
  6. Sailonline Yacht Club Member KaSToR
  7. Sailonline Yacht Club Member CollegeFund
  8. Sailonline Yacht Club Member bonknhoot
  9. Sailonline Yacht Club Member vida
  10. Sailonline Yacht Club Member sassy63

View full list

Series

Mobile Client

SYC members have the benefit of access to our mobile/lightweight web client!

The mobile client