Post by
YourMomSA | 2019-05-11 | 14:45:16
Presumably at some point in there it also applies the 2-kt minimum.
I was hit pretty hard at the very end of my first Yokohama run by the difference between the server data and the onscreen data. A 2-kt dead spot came through the finishing area, and the forecast changed just as I was approaching, so I was encountering 40-degree differences between the angle shown in the interface and in the dashboard. I ran aground trying to sail TWA. Total mess. Should have straight-lined it with C0 and ignored the sail warnings. Won't matter though, if I can do a faster run later.
That experience and this topic have me wondering a few things:
-When server and client differ, which matters?
-Which side drives the autosails decisions?
-Which side drives drives the sail choice recommendation when manually choosing sails?
-Which side drives the onscreen "wrong sail" notificaiton?
-Which side drives the "wrong sail" email notification from the radio?
My guess is... server, server, client, client, server... Meaning you can't trust your eyes in those situations and need to either rely on the autosails or trust the dashboard over the client's sail messages when choosing sails manually.
A related question... Anyone know what tolerance is built into the autosails decisions? I assume it doesn't change sails immediately when a new sail is 0.001 kt faster than the existing sail, or there would be excessive problems with sails flipping back and forth. But if I'm right, then it could also mean there would be times when you might sail with a slightly incorrect sail for a long period of time, failing to exceed the autosails threshold for a change, if you don't change manually. Which gets tricky if you can't trust the client data. Not a big enough topic to matter often, but interesting to understand.
Anyway... I was actually responding because of Cvetan's proposed experiment. I have a thought on that, which is that perhaps enough people are interested in the topic for the experiment to be worthwhile, but perhaps no single person is wanting to do the whole thing. I'd like to suggest that if three volunteers can be found, it could be done as a team effort:
-Volunteer 1: Weather / GFS guru: Identify the best coordinates for the test, and advise the Data Gatherer when to capture the data.
-Volunteer 2: Data Gatherer: This can be anyone with the Dashboard installed who doesn't mind taking a Yokohama Ultime to coordinates proposed by the Weather Guru within a few days' sail of Honolulu. I'm guessing somewhere near Fiji. When you get very close to the precise coordinates, change to the wrong sail, so that you can sail exceptionally slowly. Go to exactly TWA 0.0 when at exactly the desired coordinates. Then capture the required data when the Weather Guru recommends. The key is to be at exactly the right coordinates for a couple hours or more. Preferably for days. Main skills required are patience and the ability to get your boat to a precise coordinate and keep it there.
-Volunteer 3: Data Analyst: This is the person who knows how to use the gathered data, and the GFS data, to obtain the interpolation details. I think this person also needs to be able to advise the Weather Guru on what kind of weather is needed... Simply a big wind shift? Or do we need a case where the new forecast is going to significantly vary from the prior forecast for the same time (ie, volatility in the wind or forecast)? And... is it ok if the windspeed is 2.0, or does it need to be in a place where the wind is larger while still being volatile? Because it's easy to find wildly variable forecasts around the Solomons, but it's also a lot of 2.0.
Just thinking aloud. No worries if we aren't able to assemble a team for this analysis, particularly given that I'm not volunteering for any of the roles myself.
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