Evaluating wind models in 2025 Sydney-Hobart Race

 We have been following the TransPac52 fleet in the 2025 Sydney Hobart Race as a way to learn about evaluation of  currents and winds and routing for practice in our online marine weather and electronic charting courses. 

At about one and half days into the Race as boats approached Bass Strait, they were beating into strong southerlies (25 to 30 kts) flowing against some 2 kts of current, which created tremendously steep and violent seas.  Three of the five TP52 fleet have retired from the race, with some 17 others at this point. 

Of the two left, they are on different tracks, one that looks more favorable at this stage.  Here we will look at the wind models, comparing 1 GFS, 2, ECMWF, and 3 ICON.  Earlier in the race it appeared that ICON was more favored, but it also had winds too strong inland at the start.  We shot out of the Bay way to fast and once around the corner and into more dependable ocean winds, we hove-to to wait for the TP 52 fleet, then started the routing again, using ICON and enhanced OSCAR currents.

Below we see the situation with currents approaching the Strait, which we discussed earlier.

These are the OSCAR currents that match the AU studies. C would be logical place to be with 2+ kts of favorable current, but not when you are beating to the south against strong wind. Seas too big. Normally we would head to the beach, as Highly Sprung #2 has done to get out of the current—but current is likely flowing north there in this case. It looks like Frantic has found a nice wind median with light favorable current... assuming of course that this model, which matches the AU study (cited in the video above), is correct. 

The boat tracks shown are from the DCC option in qtVlm (menu Boat/Race Data DCC) that fetches and plots the boats from any major yacht race with standard tracking, such as YB. (I will add a note on that function after the race.)

As for wind, it looks like at this time in the race, at this location, the three models we have been following are in near agreement.  We look at the three points A, B, and C above, which we can compare to a corresponding ASCAT pass.

Viewed in qtVlm, Black is GFS, red is ECMWF, and Blue is ICON.  The above view is 1200 on 12/27/2025, and there is an ASCAT pass at 11:56 shown below (METOP-B, Ascending).  

Here we see the corresponding 25 at C, 15 at B, and 10 at A. In short, the three models agree with each other and with the ASCAT, so we can route with either of them... BUT, we are likely best to use GFS as it has the wave data in it, and then we can turn on some routing filters that account for sea state. More on this shortly..

More specially, here are meteograms at A, B, and C, which is from 1600 (4hr later), but with the same relative values and conclusions. 

Look at the winds on the far left for that time, and then note that the three models agree in speed and direction, numbered as above, now and for the next two days. Solid lines are wind speed; dots are wind direction.