Profile for jakob

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Name	jakob
Email Address	jakob@sailport.se
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Posts	364
...one of the guys behind the game...

2011-06-06 06:56:28

Re: IMSYC 2011

Board » General Discussion

You people are fantastic! What enthusiasm and engagement!!! I will try to get some students to this thread.
...one of the guys behind the game...
2011-05-02 06:35:10

Re: IMSYC / SOLstice Cup

Board » General Discussion

You find them in Homework set 5 and 6.
...one of the guys behind the game...
2011-05-02 06:08:28

Re: IMSYC / SOLstice Cup

Board » General Discussion

...and if you want to play around with hull shapes etc to investigate effects on CP, trim, stability etc you might want to try the msy_hydrostatics-code that I put on the same web-page. The code lets you import hull shapes and then stretch them in various ways
...one of the guys behind the game...
2011-05-01 18:35:20

Re: IMSYC / SOLstice Cup

Board » General Discussion

Regarding IMSYC: If you are interested in the rule for the IMSYC race 2011 you can find it here http://www.kth.se/polopoly_fs/1.47075!IMSYC-66%20rule.pdf
I have about ten students designing boats for the race )

/Jakob
...one of the guys behind the game...
2011-01-15 12:33:46

Re: Leg 2 IMOCA Global

Board » Sailonline Race Committee » Races

Hi

As always in SOL: Changing course, maps etc in the middle of a race is generally a bad idea. Main reasons are:
1) the communication problem. How do we make sure that we reach all boats with the info?
2) We have very little control over when the changes become visible in the clients. Often, a clear-cache is needed (or long time).

I vote for not changing courses etc unless absolutely vital.

/Jakob
...one of the guys behind the game...
2010-12-06 19:48:24

Re: NOAA vs SOL weather

Board » Technical Support

...well you should be careful with those softwares... especially when there is a Sailplanner available for free
...one of the guys behind the game...
2010-12-05 20:58:26

Re: NOAA vs SOL weather

Board » Technical Support

Hi all,

You are basically all correct I am the first to admit that there are many ways of doing this and that we did not spend weeks of thinking when choosing algorithm - but it works. Also (Hubert) the game winds will only correspond exactly with the GFS-forecasts when the time is exactly the time of a certain forecast frame and the point of the "observation" is exactly that of a forecast nodal point. Thus, colour coding would not be of any use at all...

Why this attention? Is it just curiosity or weather-rounting ?

Regards
Jakob
...one of the guys behind the game...
2010-12-03 16:17:40

Re: NOAA vs SOL weather

Board » Technical Support

Hi

So, about the interpolation of weather in time and space Maybe some out there is longing for a short one-liner as explanation but I am afraid there is a little more to it… Here is in short the steps we take to get an "observation" (as we call it) at an arbitrary time (called t) and location based on forecasts.

1) Find the two forecast time steps (here called t1 and t2) surrounding the time t.
2) In space we simply use linear interpolation (in the 2 dimensions lat/long) of the forecast-data in the 4 closest forecast-nodes in the grib-file. Since the forecast has separate fields, one for northerly wind and one for easily wind we need to treat these entities separately, in our case by using complex notation. We also need to do this for both frames t1 and t2 from step 1 which thus gives us a set of two complex-valued space-interpolated wind speeds, one at t1 and one at t2.
3) Now we need to interpolate in time as smoothly as we can. We chose to do this using simple shape functions ensuring continuous wind speed and actually in our case continuous time derivatives.

Now, there are naturally many ways of doing this. One draw-back of this kind of interpolation is that we loose energy. Imagine the situation with constant wind speed but rotating wind direction so that at t1 the wind is due easily and at t2 it is due westly. In our interpolation we would (falsely) get that the wind speed at the time (t1+t2)/2 would be zero.

Also note that we do not always use the GFS model from NOAA. In particular around Sweden we have more detailed forecasts.

Hope this helped a little.

Regards
Jakob
...one of the guys behind the game...
2010-09-19 15:00:56

Re: OCTOBER 2010 - draft calendar

Board » Sailonline Race Committee » Race Calendar

Hi.

We all remember the Irish-rock episode. The problem that time was the unauthorized use of protected brand names. From that point in time SOL has been, and will continue to be, careful and considerate in terms of naming races. However SOL is not by any means scared of racing between locations in the geography where others, IRL or virtually, also race. Until proven wrong SOL is of the opinion that it is totally ok for anyone to race "similar time-similar route" as IRL-races. No-one has ever raised any legal aspects regarding this. However I do want to point out that if SOL administrators (Godesses etc) do not see that a certain race fits the calendar it is up to the community to argue and be sugary ) Happy sailing /Jakob
...one of the guys behind the game...
2010-06-28 14:46:05

Re: Rename boat

Board » Technical Support

Done
...one of the guys behind the game...

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Auckland to Fiji 2023
Welcome to Auckland and, for the fifth time in Sailonline's history, an epic race to the Melanesian island of Fiji, some 1144nm away. The iconic Steinlager 2 has traditionally been our boat of choice for this event, including in 2020, the last time we raced the course – alone, unaccompanied by a real fleet as it had been #COVID19 quarantined. Alas, this year we will again be racing unaccompanied as low entry numbers has seen the real race cancelled. Hopefully, though, some of the real sailors from the Royal Akarana YC, hosts of the real event, will be joining us online to pit their skills against ours in the ever-changing forecast winds.
Race #1675
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Susan Hood Trophy Race 2023

Lake Ontario Offshore Racing (LOOR) welcomes racers to the third virtual Susan Hood Trophy race. This is a 75nm weekender on western Lake Ontario starting and finishing at the Port Credit Yacht Club (PCYC) via Niagara and Burlington, and is one of two that will count towards a special Sailonline's LOOR Series medals. As our Beneteau First 36.7 managed the course so well in previous years, we shall race her again!
Race #1690
INFOby brainaid.de
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SoCal 300 2023

Here, once again, is your chance to participate virtually in a second race of the California Race Week calendar, SDYC's challenging 243nm (as the seagull flies) SoCal 300 from Santa Barbara to San Diego. With a broad range of boats entered in the real race, virtual SOLers will have to dig deep to remain competitive in our trusty Santa Cruz 52s.
Race #1674
INFO by brainaid.de
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Cape Town to Auckland 2023
Welcome to this second RTW race 2023. It's also the June edition of this year's ocean race championship. The course is slightly different from the one sailed in 2020, which then also was part of the RTW series.
This time we will race in the IMOCA 60 foil, as in all RTW races this year. That should guarantee the fun in the South Seas in a truly tough race.
PRIZE: SMPF
Race# 1685
INFO from brainaid.de
IMOCA 60 foil Particulars
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CA 500 2023

To celebrate the 50th anniversary of the TransPac Ocean Race in 2019, the organisers of the California Race Week introduced a new longer distance event for line-honours machines. Popular with the largest maxi trimarans, this CA 500, 500nm from San Francisco to San Diego, repeats in 2023, and if you don’t own a maxi trimaran, Sailonline are delighted to have the honour to, for the first time, make their virtual version available to you for a quick ethereal dash down America’s west coast.
Race #1687
INFO by brainaid.de
Maxi Tri PARTICULARS
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June 3 at 2300 UTC.
Race starts: May 26th 18:00 Registration Open!

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Lisbon to Cape Town 2023
Our second OCC race in Q2 is also our first race of a special
6-race RTW series, in IMOCA 60 Foilers, from the board of ita10267. Long bluewater legs, with the shores of the World's continents the only restriction on where you may sail, starting with a 5000nm leg from Lisbon to Cape Town. Enjoy!
PRIZE: SMPF
Race #1683
INFOby brainaid.de
IMOCA 60 foil Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCQ2 - OCCH - RTW - SUPSOL - SYC
RACE CLOSE: Thursday,
June 1 at 2300 UTC.
Race starts: May 03rd 09:00 Registration Closed

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