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Board » General Discussion » Weather - Brain Storm

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Posted by
Zorba777


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2020-06-06 08:22:54
2020-10-01 11:28:14 - Re: Weather - Brain Storm
@dtayls @Vlbex Good comments. This is exactly what I hoped to see in this discussion. As weather models and routing software become more accurate the human factor in SOL races would become smaller and smaller. That's not what we want. I think we all enjoyed the recent Melbourne to Osaka race because we had to deal with many unexpected WX changes and a lot of position changes. High WX uncertainty = more interesting race. Compare that to the current Darwin to Perth race, where the weather has not changed at all. There is hardly any new message on the chat, people just set their DCs for the next 24 hours and nothing happens. If WX becomes more reliable then we will get more Darwin to Perth type races, an fewer races like Osaka, where we all had problems and scenario changes to deal with.
There is probably still a few years time until WX models become too good, but we can already exchange ideas on how SOL could adapt to that if needed.

I think what most of us want is a realistic simulation, not just a "who has the best routing software" type competition where all you have to do is execute the ideal route. In real life sailors have to deal with real weather differing from what the WX update forecasted. Can we mimic something like that in SOL? And if so how?

Introducing a random factor that makes the grib we play differ a bit from the official GFS (or other) weather model was suggested. Personally I am not a fan of using random factors. The reason is that the people who implement or help to run SOL behind the screens are volunteers and often participants at the same time. There would always be a suspicion that insiders have knowledge (or access) to those random factors, while normal players can not see them.

So, *IF* any "random factors" are to be used to add uncertainty (and thus stop routers from finding optimal solutions/routes) then those random factors should come from the weather itself imo. For example, as the article I linked to mentions, there will be more access to near-real time weather data (from drones and buoys) in the future. Let's say we have a race in an area using GFS data as we currently do. Every 6 hours we have a fixed map that we sail. But if there are a few buoys in the given area that put real time wind data on internet then we could use those real time data to change the weather map we use in SOL every hour or every 2 hours. That could be as simple as adjusting all wind speeds on the basis of the difference between predicted wind speed and measured wind speed for the given locations and times. That's isn't to hard on the server as it is only done once and hour. But it would add uncertainty. And we can experiment how much weight we give to the real-time data, so that routing keeps some of its use, but adapting to changes in real weather becomes important too. If we do that we will have a much more realistic simulation, because that's what IRL sailors do too. :-D

Posted by
Zorba777


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2020-06-06 08:22:54
2020-10-01 11:36:37 - Re: Weather - Brain Storm
An other way to add uncertainty is by introducing a random factor that depends on the SOLers actions. The best candidate for that would be "wind shadow" that is caused by the other boats near you in the direction where your wind is coming from. When you are sailing in "dirty wind" your boat slows down a bit. This is also the case IRL sailing. By assigning a certain performance loss % if another boat is putting me in dirty wind, we would create uncertainty and introduce the sailing tactics that are know from real races.
I think this factor should be quite small to keep it practical. Maybe 98% performance if you are in wind shadow from another boat, we would need to test what works. This would cause boats to avoid wind shadow by moving away from the optimal routes that their routers crank out.
I think this would be very interesting, but more so for the short races and sprint races. In long ocean races it should be a very small factor (or not useful at all).

--- Last Edited by Zorba777 at 2020-10-01 11:38:14 ---
Posted by
dtayls


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2020-10-03 04:34:24 - Re: Weather - Brain Storm
I agree with you @Zorba that "random factors should come from the weather itself".

As you know I like the idea of using a different and more accurate model (perhaps ECMWF) for the underlying simulation but that might depend on gaining access to a high quality model to which most users do not have access.

Another approach might be to introduce a certain degree of randomness in to the simulation's weather model, but what should the source of this randomness be?

One option would be to choose a random mix of two or more models. This could be (a) fixed for the whole race or (b) change over time or (c) vary by lat&lon across the GRIB or (d) both meaning <x,y,t>.

If model volatility or uncertainty GRIBs were available then this could also be used to add a little to the randomness model but I suspect many would consider this to be a step too far :-)

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