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Profile for ij



Name ij
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Posts26
  • Re: Legality of the use of extra zoom on the apparent size of end points of finish line
    Board » Sailonline Race Committee » Rules and Decisions
    All marks and finish line endpoints are singular coordinates on server side. That is, the server thinks their diameter is zero.

    However, I don't believe those "closest" pixels are really necessary in practice anyway as we talk very very small distances per pixel. I'd recommend leaving at least 0.002 degree margin in angle to be on the safe side (it's easy to check that the COG number in the infobox changes when aiming).

    The finish line endpoints are not provided by the server currently but they are calculated by the client(s), which is a potential (small) error source on their position. There was an unfortunate incident not so long ago related to it because html5 client finish line code pre-dated my access to server-side formulas. I'd like to change this among many other things eventually such that the finish line coordinates are provided by the server so such errors would no longer be possible.

    Occasionally pixel rounding related "jitter" may result in different positioning for the very same line so "crossing" is not even well-defined if only considered what is seen visually for a line.

    --
    i.
  • Re: Public testing new HTML5 client
    Board » General Discussion
    Hi all,

    I've just updated the dev version with lots of changes. It is possible to enable DC-aware predictor already, however, there are a few caveats. The DC-aware predictor does not consider performance losses at turns correctly. Initial performance is consider correctly like previously, however, when firing any DC, the performance gets beamed up to 100% and remains there for the remaining predictor length. In addition, the calculation only runs with 30s accuracy wrt. boat movement.

    There is now BBQ warning sound and a few new ruler related buttons that were requested.

    Some changes are (should be) user invisible library updates but they might introduce new problems (or bring back vanishing fleet problem which has caused me to hold back one particular library update).

    --
    i.
  • Client Buttons Changed
    Board » General Discussion
    Hi all,

    I've now altered the "GO TO RACE" button so that it leads to HTML5 client (and race registration link likewise leads to HTML5 client).

    If you still want to access the old flash client, a smaller button above it that used to point to HTML5 client is left for your convinience. However, with the demise of Flash support in Web browsers imminent, I'd strongly recommend contacting me if you have strong reasons why you cannot use HTML5 client but need to keep using Flash client so I can see if I can somehow help the situation.

    Happy SOLing.

    --
    i.
  • Re: Public testing new HTML5 client
    Board » General Discussion
    Stable version of the client was updated today (2020-10-05). Long list of changes:

    - Longer predictor (up to 48h, see settings)
    - Relocate weather navigation buttons next to each other
    - Month is now textual in date instrument to avoid interpretation ambiguities
    - Thicker line for the downwind (when wind cursor lines are in use)
    - Improved visibility of some text fields on map (to avoid unreadable mess when TWS/TWD values are enabled)
    - 10m x 10m box to show scale when using extra zoom (can be disabled in settings)

    - Improve ranking tab sort order, sort secondarily based on ranking
    - Ranking tab includes DBL column for fleet races (please don't report those minor inconsistencies in the numbers, it's not a bug in the client)
    - Added "race boundary" labels to help newcomers
    - Use white text for instruments in night/dark mode
    - Remove duplicated labels when the same mark is used more than once for the race course
    - Limit TWS contours density with far-away zoom levels to improve performance


    - Coordinate instruments obey the coordinate format in settings
    - Prevents another fleet boat from showing up as own fleet boat
    - Fix boat key (boat label on map) wrap issues
    - Various clock synchronization improvements that are triggered if local clock is off by more than 2 minutes from the time on the server
  • Re: Weather - Brain Storm
    Board » General Discussion
    There's no differentiation for non-profits. The ECMWF licensing is using the very same conditions for non-profits and commercial. From https://www.ecmwf.int/en/forecasts/accessing-forecasts/licences-available:

    "Provide a service using real-time ECMWF products

    If you wish to provide a commercial, non-commercial, or not-for-profit service to third parties using ECMWF real-time products, you will need to accept the terms of the ECMWF Standard licence and pay for the associated data and handling costs."

    I don't see any way around paying, regardless of non-for-profit or not (research, as expected, doesn't allow providing any services and it would be really twisting the rules anyway).

    If a "secret" wx is desired, it's relatively easy to create one with WRF, just some parameter tweaks that remain secret are required. But then we will find out the WRF is volatile enough in itself so the secrecy loses its useful/meaning (one cannot plan long-term route with wrf even nearly as reliably as with gfs).

    A "secret" wx would really just force people to sit in front of computer whole the time, especially in low TWS conditions, because twa steering becames a joke for racing purposes (or not to participate at all which is hardly useful goal to aim at ;-)). ...It gave me another idea though, maybe the platform should allow truly crewing the same boat with different usernames to share watches (different from private boat sharing that is of course possible even today). Then it would be a bit less solo mission to keep an eye on the wx.

    --
    i.

    --- Last Edited by ij at 2020-09-29 19:48:35 ---
  • Re: Weather - Brain Storm
    Board » General Discussion
    Of the available forecasts, these regional ones certainly seem interesting for higher than GFS precision:
    - ICON-EU
    - AROME
    - NAM conus & maybe caribbean nests

    For global models, I don't think there are freely available alternatives with enough incentives to make it worth replacing GFS, and many have clear disincentives such as non-even forecast lengths for different times.

    Without at least seriously trying out with GFS 0.25 x 0.25 first, I wouldn't spend too much effort on the other global models that are freely available. (ECMWF is not freely available, if it would be, it would certainly seem attractive enough).

    In practice, the blocker for any high-res wx is the lack of tiled wx support which requires too large modifications before some other blockers are removed first so it's not going happen over a weekend (I've definitely made some progress towards that direction but it's a big task with rather limited help so far). Even the WRF weathers which we've not been able to use for some time were somewhat big data sizewise for anything else than those small sprints (but certainly made the races much more interesting, IMHO).

    --
    i.
  • Re: Weather - Brain Storm
    Board » General Discussion
    Many numbers you see on those lists are not correct. ECMWF updates 4 times per day but only to +90h on every second run (Similar to some other forecast runs with other models).

    Also, they explicitly mention not-for-profits in their license selection guidance so you're just dreaming and there's little point in trying to ask anything from them.

    --
    i.
  • Re: Weather - Brain Storm
    Board » General Discussion
    Just a minor note from some ECMWF validation report now that I came across one: in 10m wind at 5 days the frequency of large errors is around 4% (+/-1 due to year cycle) now so it's in ballpark with those 90/80% numbers. (And in temps slightly worse.)

    GFS is likely somewhat worse than that given ECMWF is generally considered slightly better although both can be shown to be better in selected cases.

    What is means to routing accuracy is hard to know without looking deeper into the report (if it's told at all). The distribution of the large errors over time matters too much. But if distribution would be uniform (it very likely isn't), one would very likely hit one large deviation in almost every 2 weeks long race. And how bad the large error % gets when consider beyond 5 days, no idea.

    --
    i.


    --- Last Edited by ij at 2020-09-09 21:01:19 ---
  • Re: Weather - Brain Storm
    Board » General Discussion
    Comparing 0.25x0.25 wx grid with 1x1 (I forgot to make the arrow density the same so please disregard that difference):

    https://postimg.cc/F19n3Yjp

    --
    i.

    --- Last Edited by ij at 2020-09-07 22:18:39 ---
  • Re: Weather - Brain Storm
    Board » General Discussion
    I agree with bonk that 80% reliability is really a joke. Even 90% is not really something I'd boast about. It's worth to remember the error starts to rapidly accumulate. It's unlikely to be dropping linearly but more like larger error also leads to much larger error accumulation (and thus uncertainty).

    I've never seen the definitions of that kind of % metric anyway (so if somebody has pointers to some scientific papers evaluating forecast long-term accuracy, please, I might read myself). But I wouldn't be surprised if it turns out quite bogus or irrelevant to measure what kind of accuracy we're talking here.

    --
    i.

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San Diego Islands Race 2021

Sailonline is partnered with San Diego Yacht Club for the 2021 Islands Race. This year we are racing TP52s to compete against the real crews in the 132nm course from Long Beach, around the Catalina Islands to San Diego.
Race #1435
INFO by brainaid.de
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Bora Experience 2021
Visit the Adriatic Sea for Bora Experience 2021.
Bora winds are feared by local sailors and tend to blow most strongly during the winter months, reaching record speeds above 200 km/h (125 mph). In our virtual Seascape 18 we fear not, and you are invited to race from Venice to Dubrovnik, navigating between the islands along the Croatian coast.
Race #1448
INFO by brainaid.de
Seascape 18 PARTICULARS
WX Updates:
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Ranking: SYC
Race starts: Feb 27th 16:00 Registration Open!

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New Hebrides Slalom 2021
Welcome… back to the carved-out coastal backdrop of New Caledonia’s opencast nickel mines, for a quick getaway in elegant Italia 14.98's to the islands of the Coral Sea across the Loyaute Basin and on via a mazy zig-zag north to a finish line in exotic Vanuatu's Big Bay. Only 578nm; enjoy!
Race #1425
INFOby brainaid.de
Italia 14.98 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking:
SYQ1 - SYCCH - SUPSOL - SYC
RACE CLOSE: Thursday,
March 4 at 2300 UTC.
Race starts: Feb 23rd 18:00 Registration Closed

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Aland Sea TIMED Race 2021
Norrtalje Segelsallskap, 70km NE of Stockholm was founded in 1920, and time was when the society’s season opened with a challenging offshore race from the club line off Flaten island at the mouth of the long and narrow Norrtaljeviken, out onto a triangular course around the Aland Sea, to finish at Simpnas slightly to the north on Bjorko island - some 78nm in total. A fine race that SOL, being from these parts, ran annually up until 2013. Last run in autumn 2018, we return here to race the course again in the form a TIMED RUN in our flashy Club Swan 50s.
RE-REGISTER HERE to race again after finishing a run.
Race #1444
INFO by brainaid.de
Club Swan 50 Particulars
WX Updates:
0430 / 1030 / 1630 / 2230
RANKING:
TRQ1 - TRCH - SUPSOL - SYC
RACE CLOSE: Sunday, 28 February at 23:00 UTC
Race starts: Feb 15th 12:00 Registration Open!

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CCA Delivery Cruise 1 2021 - Sandwich MA to Halifax NS

The Cruising Club of America invites you to join them on a (virtual) delivery cruise starting from Sandwich, Massachusetts, the oldest town on Cape Cod in the USA to Halifax, Nova Scotia, Canada, some 354nm away. Once we clear the tip of Cape Cod at Race Point our rhumb line course will be 70 deg T for 225nm across the Gulf of Maine to Cape Sable NS, so the best delivery departure window for sparing the crew and gear pounding into a northeast winter gale across Browns Bank will likely be following a frontal passage with strong favorable westerly winds. You may choose one of two boats, both tailored for cruising and new to Sailonline's boathouse, so flip a coin, study their Particulars sheets and make ready! You may start at any time after 1900utc on 8 February 2021 and you must arrive in Halifax by 4 March at 2300utc.
Race #1417
INFO by brainaid.de
Santa Cruise 52 PARTICULARS
Passport Cruise 40 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
RANKING: NONE
Race starts: Feb 08th 19:00 Registration Open!

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Haifa to Sao Vicente - 2021 ESRW - Leg 1
Welcome to bonknhoot’s alternative round the world race, there where it is wide, in six legs, following the setting sun – the ESRW Equatorial Sailonline Round the World Race; equatorial to differentiate it from more traditional antarctical circumnavigations. Expect then to cross the equator frequently, although on this 3500nm first leg from Haifa to the Cape Verdes in Ker 40s you should probably stay north of it. Being a proper ocean race, there are no intermediate waypoints, but please try to leave Tangiers to port anyway.
Race #1427
INFO by brainaid.de
Ker 40 PARTICULARS
WX Updates:
0430 / 1030 / 1630 / 2230
Ranking: ESRW - SYC
RACE CLOSE: Thursday,
March 4 at 2300 UTC.
Race starts: Feb 05th 16:00 Registration Closed

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