start time & leaderboard #'s

[cpurvis]

Hi, all. The race mappers are live. You may have notices two quirks:

* The race start time has been set to Tue May 15 2007 19:00 EDT. The race won't start until tomorrow, of course, but the mapper needs a little spin up time until the race really begins. So you can expect that sometime tomorrow late morning that the mapper will be updated w/ the right start time.

* The leaderboard has weird estimated finish times. Since the leaderboard bases the ETA and rankings on an average boat speed and since the boats have not moved much of anywhere, the numbers will be skewed until a little after the race starts. That was a long sentence.

Please enjoy, and if there are any questions, shout them out!

[Dr Mats]

Fantastic information here!

Where do you get your water temp and wind overlays?

How often are they updated?

Thanks.

[cpurvis]

Hi, Dr. Mats.

# What is the source of the wind and wave data?

The wind and wave data are from a numerical weather prediction model called NAM that is run by the Nation Center for Environmental Prediction at the National Weather Service.

# What is the source of the Gulf Stream data?

The Gulf Stream layer shows the sea surface temperate from the AVHRR imager on the NOAA polar orbiting satellites. We receive the data from either NOAA directly or from the Ocean Remote Sensing Group at Johns Hopkins University.

I usually update the SST daily on the mapper. If it's a really spotty composite, I'll let the previous composite stand.

The wind and wave data point obs are interpolations that are based on forecasts that are updated every 6h.

[Dr Mats]

How often are the vessel locations updated?

Do I need to refresh my browser to get the latest location?

(At 1300 on 05/18 I still see them at the starting area - did they start on time?)

[cpurvis]

The trackers broadcast their signal every 2h, and it may take from 15 - 30 mins for it to make its way to the mapper.

Yes, you do need to refresh the mapper to get the latest obs.

[clark]

Hello Dr Mats,

The iBoattrack transponders send position data every 2 hours. To keep the satellite bandwidth from getting flooded, the time of the transmissions are randomly varied. Therefore, it can take upwards of 35 minutes before the positions get populated onto the multiple Internet servers.

If you are finding your data is not updating, then try reloading the page. Note: The Microsoft Internet Explorer shortcut to reload a page is the F5 key on the top of your keyboard.

Clark
iBoattrack Manager

[Dr Mats]

The trackers broadcast their signal every 2h, and it may take from 15 - 30 mins for it to make its way to the mapper.

Yes, you do need to refresh the mapper to get the latest obs.

Cool - so, can we expect to see the entire fleet position updated 20-30 mins after each even numbered hour? (1430, 1630, 1830, etc)

[clark]

Dr Mats
That is right - with a few exceptions...
There are times during a race when an iBoattrack transponder will get covered by a sail or something else that will keep a transmission from reaching the low earth orbitting satellite. In these cases, the boat position for that timeframe will be missed entirely.

Clark

[pen]

The corrected times seem skewed. Are they truly corrected bythe PHRF ratings? When I look at the ratings Celedon has a PHRF of 87 and LungTa 156. Are they ranked including the time owed by the faster boats or will that be done in the end? The boat have such a tight grouping how can it be accurate?

[cpurvis]

The estimated corrected times are tricky, and we debated whether or not to show them before the boats actually finished. But since that's the way the LB is ordered, we thought we'd show these #'s and roll w/ the punches!

The estimated corrected times are based on the estimated finish time which is a product of the average DAILY vessel speed since start time. This avg. daily speed is combined w/ an interpolated distance to the finish since not all obs are taken at the same moment in time. And then the distance and PHRF are tacked onto the end of those #'s like normal.