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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

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The Tall Ships Races 2020 - Race 1

Welcome to the first of three virtual races representing this year's European Tall Ships Races - a race of 220nm from Lisbon, Portugal, giving Cabo de Sao Vicente and Ponta de Sagres plenty of searoom, to Cadiz, Spain
NOTE:Starts and Finishes in tall ships racing are always offshore to avoid conflict with shipping and shipping lanes.
Race #1352
INFO by brainaid.de
Clipper 240 Particulars
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SSANZ Triple Series 2020 - Lewmar 60 PIC

Welcome to Auckland, New Zealand and, for the 9th successive year, Sailonline is happy to provide the virtual version of the brilliant three-race SSANZ two-handed series, raced around the waters of the Hauraki Gulf off New Zealand’s North Island. Our direct competitors in this 2020 Lewmar 60 PIC course are the real racers of the Young 88 Association.
Race #1370
INFO from brainaid.de
Young 88 Particulars
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Ranking:
SSANZ - SYC
ALT. CLIENT Classic
Race starts: Jul 03rd 21:15 Registration Open!
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Pacific Cup 2020


Pacific Cup Yacht Club (PCYC) invites all sailors and SOLer's to participate in the virtual edition of this biennial race from San Francisco Bay, USA, to Kaneohe Bay on Oahu's east coast in the Hawaiian Islands 2070nm across the Pacific Ocean.
Race #1371
INFO by brainaid.de
Santa Cruz 52 Particulars
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0430 / 1030 / 1630 / 2230
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ALT. CLIENT: Classic
Race starts: Jul 02nd 19:00 Registration Open!
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Auckland to Uruguay - 2020 RTW - Leg 3
The third leg of Sailonline's Round the World Race 2020 sees the fleet navigating its way from Orakei, Auckland, New Zealand, across the Pacific and up the South Atlantic to Punta del Este, Uruguay
For your transit from ocean-to-ocean you may leave Tierra del Fuego to port or to starboard, as you please.
PRIZE: SMPF
Race #1362
INFO from brainaid.de
Orange 125ft Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: OCCH-OCQ3-SUPSOL-SYC-RTW20
ALT. CLIENT:Classic
Race starts: Jul 01st 20:00 Registration Open!
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