The 1240z posreport shows DFRT with a significant loss over the last 6 hr, but still with a handy lead dead upwind of the fleet. Distances are to a mark approx where they will leave the coast.
Optimal routing shows a very definite track for the fleet. Stepping offshore and a final tack to then being freed up all the way in. Shaded is a 60min sensitivity to the route for DFRT. Winds 0.25 deg GFS. Ocean and Tidal Currents from www.tidetech.org
|0.25 deg GFS model|
|Results to SANYA - times UTC|
- Tack on DFRT line, and grind them down on Bsp only
- Tack with DFRT, therefore cutting the corner slightly and reducing miles sailed
- Go beyond DFRT line in the search of a slightly better angle in
Will be very interesting to see how this is played, and each team will have a different feel for it depending on their preferred angles and strengths. Go wide and hope for an increase in pressure? Go early and have a better angle in lighter airs? My polar suggests the peak speeds for the boats in 14kt TWS is between 110 and 120 TWA. Either side of that and Bsp drops quickly.
Wind fields suggest slightly better but headed pressure for the last 100nm in E and much lighter and lifted in the W. A very quick assessment looking at the GFS 0.25 suggests if you wish to get some leverage then get further W of DFRT, however will bleed miles very quickly as DFRT point at the mark. No consideration here for the best angle to approach the Island/finish.
An ensemble run using the GFS control and perturbations, the shape of the route remains the same, however it shows the options for timing of the course change to the N. A good mean cluster with only a few outliers.
|GFS Ens control and perturbations|
And finally, a video of the run...