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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 » 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 » 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:

Jakob's Birthday BBQ Race 2014
Its Easter 2014 AND the weekend of Jakob's birthday, so time to celebrate with the traditional 30nm race from Sandhamn to Jakob's mooring in Stockholm's Archipelago. A splendid Sailonline-style bbq party awaits! SOL's home waters are always challenging so... the race is on in our X35s! Grattis pa fodelsedag 2014 Jakob!
Race #678
NOR from brainaid.de
X35 OD POLAR
WX Updates: 0430 / 1030 / 1630 / 2230
Ranking: SYC
ALT. CLIENT Classic
Race starts: Apr 19th 11:00 Registration Open!
GO TO RACE

2014 International Paints Auckland to Tauranga Race
SOLers are invited to race the 124nm from Auckland to Tauranga in this annual classic! Sadly our Young 11s won't have Beale 35 Open Country to compete with this year.
Race #677
NOR from brainaid.de
Young 11 POLAR
WX Updates: 0430 / 1030 / 1630 / 2230
Ranking: SYC
ALT. CLIENT Classic
RACING
RACE CLOSE:Saturday, 19 April at 1000utc
Race starts: Apr 16th 22:00 Registration Closed
GO TO RACE

Rolex China Sea Race 2014
Welcome to the 2014 running of the prestigious Rolex China Sea Race - a classic biennial bluewater race of 565nm from Hong Kong to Subic Bay, Philippines.
Race #665
NOR from brainaid.de
TP-52 INFO
WX Updates: 0430 / 1030 / 1630 / 2230
RANKING: SYC
ALT. CLIENT: Classic
RACING
Race starts: Apr 16th 05:20 Registration Open!
GO TO RACE

Sailonline RTW 2014 - Leg 3 - Australia to New Zealand
Welcome to the third leg of Sailonline's race in the footsteps of Steinlager's Whitbread RTW Race of 1989/1990 - this Leg is from Fremantle, Australia to Auckland, New Zealand - 3,013nm
Race #669
NOR from brainaid.de
Steinlager 2 POLAR
WX Updates: 0430 / 1030 / 1630 / 2230
RANKING: SYC-SRTW
ALT. CLIENT: Classic
RACING
Race starts: Apr 04th 06:00 Registration Closed
GO TO RACE

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