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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:

2017 40' Series Championship Q3&Q4 - Lord Howe
Welcome to the final 6th of 6 races in this season (Q3/Q4) of our 40' series!
We will use the iconic 412nm racecourse from Gosford to Lord Howe Island.
The island is considered one of the most beautiful islands in the Pacific - one of just four island groups to be inscribed on UNESCO’s World Heritage list for the global significance of its natural beauty and heritage. Located in the Tasman Sea between Australia and New Zealand, administratively it is part of the Australian state of New South Wales.

HOW TO BE DISQUALIFIED!!
READ THIS !!!!

Race # 1099
INFOfrom brainaid.de
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
40CQ3&4 - SYC
ALT. CLIENT:Classic

Race starts: Dec 14th 02:00 Registration Open!
GO TO RACE

SWR 17/18 Leg 3 - Cape Town to Melbourne
This, the third of eleven legs of the 2017/18 Sailonline World Race, takes us from Cape Town to Melbourne!
After departing Cape Town in probably light winds and passing Cape of Good Hope, the keyword is "The Westerly Stormtrack" and to catch that, the weather will take us deep down south through the "Roaring Forties" and beyond, and then blow us toward Melbourne.
The southern race boundary has been set at 60°S to mark the Antarctic Ice Exclusion Zone, which will, hopefully, give us a clear run.
Race #1101
INFOfrom brainaid.de
OD65v3 Particulars
WX Updates: 0430 / 1030 / 1630 / 2230
Ranking: OCCH-OCQ4-SUPSOL-SWR-SYC
ALT. CLIENT:Classic
Race starts: Dec 10th 12:00 Registration Open!
GO TO RACE

Christmas to Christmas Islands 2017
Having discovered that there is more than one Christmas Island some years ago, each year in the run up to the festive season, Sailonline races from the Pacific island to the Indian Ocean one - a distance of 5,837nm. The choice of route is entirely up to you! Fair winds!
Race #1098
INFO by brainaid.de
Super Maxi 100 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
RANKING: NONE
ALT. CLIENT: Classic
Race starts: Dec 02nd 02:00 Registration Closed
GO TO RACE

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SYC Ranking

  1. Sailonline Yacht Club Member bonknhoot
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Series

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