Transpac Report

	Analysis on July 2, 2001 of Class 4 : Click Here
	Analysis on July 3, 2001 of Class 1 : Click Here
	Analysis on July 4, 2001 of Class 1 : Click Here
	Analysis on July 5, 2001 of Class 4 : Click Here
	Analysis on July 6, 2001 of Classes 1,4 : Click Here
	Analysis on July 7, 2001 of Classes 1,4 : Click Here
	Analysis on July 8, 2001 of Classes 1,3 : Click Here

Transpac 2001 - Daily Position Analysis on 7/9
(Class 1; Day 10 at 07:00 PDT)

Routing software uses predicted wind over a number of days between the start and destination, as well as characteristic boat speeds (how fast the boat can sail at different wind speed and wind angles ), to estimate boat speed at various points and times during the race. The software tries out all possible routes to find the fastest, balancing favorable and unfavorable wind patterns at different locations, and at different times, over the entire race.

On this page we compare actual boat positions during Transpac 2001 to routing solutions derived from our "Force 4" software. The solutions are based on 10-day wind prediction files (MRF) and boat performance parameters (polars) representative of the class.

Polars do not correspond exactly to any given boat. We will look at different classes on different days during Transpac 2001 to provide an overview of the race and the tactical considerations of routing for the participants.

Almost there !! Positions of Pegasus "1," Pyewacket "2" and Chance "3" at 0700 on 7/9. Pegasus is just 92 miles away from the finish, with Pyewacket at 108 and Chance at 124.

HOW TO DO A ROUTING CALCULATION

Now that the race is almost over, we can do a comparison of the actual route followed by Pegasus (and the other top boats in Div 1), compared to a day-by-day router computation (all using a MRF wind prediction file known at the start). The winds were very light the first day, leading to an effective restart some 90 miles offshore on day 2. For this reason the comparison will be made starting at that position, at 0700 on 7/2.

The routing gives a best "red" course north of the rhumbline, but to be conservative we pick an initial course to "72" on the black course, reached at 1200 on 7/4 (winds are shown at that time). This course is only some 2 hours slower, and at this point the boat is closer to the finish (1511 vs. 1516 nm) than on the red course. [The black course is restricted to stay close to the rhumbline.]

We do a second routing from "72" at 1200 on 7/4, giving the solution below. The black course now is some 3.5 hrs slower, so we pick a point "73" where the red and black diverge as the next waypoint, where the boat will be at 1200 on 7/5. The winds shown are at that date and time (all generated from the original MRF file).

We do another routing from "73" at 1200 on 7/5, and pick another waypoint at "74", slightly below the red course beyond where the red and black diverge. The boat is predicted to reach this point at 1200 on 7/6, with winds as shown.

We do another routing at 1200 on 7/6 from "74" and again pick a next waypoint "75" between the red and black routes. The expected boat positions and winds are shown at 1200 on 7/8. From there we route to the finish.

We can now combine the router-computed waypoints into a course, shown by the sequence of points A-F below, joined by the red and magenta lines. For comparison, we show the actual positions of Pegasus as points A and 2-6.

Another function of Force 4 allows us to "solve" a course, evaluating wind and current (none here) in each leg to predict boatspeed and to compute corrected headings and times. This function gives the following result for the router-computed course.

Begin Time: 7-2-2001 7:00:00
A to B: 646.6 nm 251.0 degT 2 dy, 7.9 hr 14:56:00 07-04
B to C: 276.3 nm 272.5 degT 1 dy, 0.6 hr 15:31:00 07-05
C to D: 253.3 nm 267.3 degT 1 dy, 1.1 hr 16:35:00 07-06
D to E: 460.3 nm 249.3 degT 2 dy, 0.8 hr 17:20:00 07-08
E to F: 525.8 nm 233.3 degT 1 dy, 22.8 hr 16:08:00 07-10

Total Distance: 2162.3 nm
Total Time: 8 day, 9.1 h * Note: computed from 0700 on Day 2

The solution for the actual Pegasus course is as follows:

Begin Time: 7-2-2001 7:00:00
Wind Model: Transpac 7/2 to 7/12-G (Scale: 1, Rotate: 0)
1 to 2: 292.6 nm 243.2 degT 1 dy, 1.4 hr 08:24:00 07-03
2 to 3: 304.2 nm 244.3 degT 1 dy, 2.8 hr 11:14:00 07-04
3 to 4: 248.5 nm 245.0 degT 1 dy, 2.9 hr 14:10:00 07-05
4 to 5: 284.3 nm 268.8 degT 1 dy, 1.0 hr 15:09:00 07-06
5 to 6: 647.8 nm 259.8 degT 2 dy, 18.0 hr 09:09:00 07-09
6 to F: 393.1 nm 239.8 degT 1 dy, 10.9 hr 20:00:00 07-10

Total Distance: 2170.5 nm
Total Time: 8 day, 13.1 hr * Note: computed from 0700 on Day 2

The comparison predicts that the router-computed course would have been some 4 hours faster than the actual course. Boat to boat, the separation between the top boats has typically been under 1 hour.

*For more Transpac Coverage; see our Local Knowledge "GOFLOW" website:*	www.goflow.com Click Here
Interested in Other RACES ??	CLICK HERE
Want to know more about "Force 4"?	CLICK HERE
Our specialty is high-resolution current- prediction models for racing venues all around the world. SEE EXAMPLES Contact Us for Info	Our "routing" works just as well for currents. If you are doing the Big Boat Series in SF, this is a must!! (BIG Flood !!)