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Profile for jakob



Name jakob
Email Address jakob@sailport.se
AvatarUsers avatar
Posts364
Board Signature
...one of the guys behind the game...
  • 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...
  • Re: IMSYC / SOLstice Cup
    Board » General Discussion
    You find them in Homework set 5 and 6.
    ...one of the guys behind the game...
  • 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...
  • 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...
  • 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...
  • 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...
  • 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...
  • 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...
  • 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...
  • Re: Rename boat
    Board » Technical Support
    Done :-)
    ...one of the guys behind the game...

Races

Next Race: 00d 00h 00m


Current Races:

Gulf Run 2021
It is 550nm on a course of 175 true from Dingle to Vigo, and from Pensacola to Yucatan as well, across the Gulf Stream and The Gulf respectively. It's warmer down in The Gulf, so we return to its azure waters for a re-run in J-130s of a course designed by RainbowChaser back in 2012, but only first run in 2018. Bring your deck chairs and the barrier cream.
Race #1513
INFO by brainaid.de
J-130 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC
Race starts: Oct 26th 21:00 Registration will open soon

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Isla del Sol Re-Run 2021
Scanning the globe for special sprint locations, our intrepid course designer Renegade came across Isla del Sol in the middle of the world's highest navigable body of water, Lake Titicaca. We tried to race around it last month, but at 3812m above sea level, comms to our boats broke down for a little while, and our SRC decided to abandon the race, so we are running it again: 26nm RTI in "how-did-we-get-them-here?" Fox 9.50s.
Race #1512
INFO by brainaid.de
Fox 9.50 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
SPRQ4 - SPRCH - SUPSOL - SYC
Race starts: Oct 23rd 16:00 Registration Open!

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China Coastal Race 2021


Racing in reality around the world is tough during a global pandemic and RHKYC's calendar is having to be flexible too so instead of a run to Vietnam, welcome to a competitive coastal race inside Hong Kong waters - 97nm in TP52s against the local fleet!
Race #1519
INFOby brainaid.de
TP52 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC
Race starts: Oct 23rd 03:00 Registration Open!
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Virtual PIC Coastal Classic Yacht Race 2021


Welcome! Kia Ora! to Auckland, New Zealand, and Sailonline's annual multihull race against the NZ Multihull Yacht Club competitors over 118nm from Auckland to Russell. Sadly, COVID19 restrictions mean the real race will not be running, but we welcome real racers to our virtual event where we are racing our 60ft trimarans in this testing event in the endlessly varying conditions off the east coast of North island. As is tradition, a hearty breakfast of bacon butties and rum will welcome yachties on their arrival.
Race #1515
INFO by brainaid.de
60ft trimaran PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: SYC
Race starts: Oct 21st 21:00 Registration Open!
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ESRW6 Singapore to Kuwait 2021
Join us as we embark on our final leg(6) of the fabulous ESRW round the equator race series, this time onboard the speedy 90 foot Monohull as we wind our way out of the Malacca Strait and across the Indian Ocean 3000nm to Kuwait. It'll be steamy all the way!
PRIZE: SMPF
Race #1508
INFOby brainaid.de
90 foot Monohull PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: ESRW-OCQ4-OCCH-SUPERSOL-SYC
RACE CLOSE: Tuesday,
October 26 at 2300 UTC.
Race starts: Oct 01st 03:00 Registration Closed

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SYC Ranking

  1. Sailonline Yacht Club Member WRmirekd
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