The Ocean Race 2023 leg 2: Cabo Verde to Capetown

[Schakel]

Tonight's routing...
Situation 17z : the 3 leaders have been taken over by the cold front yesterday and gybe SE in westerlies. They are going south-east, will gybe at 23z if they follow GFS, 6z tomorrow if they follow ECMWF...
None of them will have to cross the ice exclusion zone.
the 10/02 at 0z they will be slowed by a HP ridge from Santa Helena HP. Following boats will get closer to the leaders thanks to another cold front coming from another LP that will push the HP ridge.
This CF will go with the boats to Cape Town. ETA 0830z the 12/02. You can see on the routing Guyot will cut his 500 milles late to just a few milles...

On the pictures : Black : GFS routing&wind, red, ECMWF routing&wind. Wind 110%. Polar : imoca_foil 105% downwind. Software : qtVlM
Pic 1 : satellite picture with current condition
Pic 2 : situation the 10/02 0z CF approaching
Pic 3 : situation the 11/02 0z
Pic 4 : situation the 12/02 0z . wind + rain

Since the doldrums, I found ECMWF has been more reliable that GFS for route planning, boats have often choose the ECMWF routing... Guyot East position was favoured by GFS that predicted a smaller HP when boats were there.

Only something else happened.
Malizia had to turn back by lack of wind.

 

[noaano]

Boat I though was 11th might be Holcim, maybe 11th has stealth AIS. Should have followed them more carefully, like I have done before.

Anyhow, boats are less than 4nm distant bow to bow and Malizia is more than 5kts slower, going to almost opposite direction.

Something happened for sure, I presume.

Edit. I think it must be 11th. There must be some delay as the tracker and sat ais don't match exactly.

 

[noaano]

It must be Holcim that is the stealth AIS -ship, maybe, 329mins since last seen by satellite.

As the others are updated every few minutes or so, there must be something wrong with their transponder or antenna, maybe.

Anyhow five boats can be seen on SAT AIS, I don't think there are that many other pleasure boats there so must be them.

 

[giegs]

If you watch and listen to the video of Melitzia above, they describe in detail how loud it is. Answer: excruciating.

Yea and I'm guessing 110+ dB at times from that. Loud. Would be interesting to get some noise dosimeters on board.

 

[mathystuff]

It must be Holcim that is the stealth AIS -ship, maybe, 329mins since last seen by satellite.

Problem with Holcim and Malizia dispatching?

Seems unlikely as 11th was closer.

 

[noaano]

Problem with Holcim and Malizia dispatching?

Seems unlikely as 11th was closer.

Holcim is the one in dimmer color.

Malizia not heading to their direction.

Guyot is outside of the frame.

Holcim is not updating at nearly the same frequency as the others, so it is not there on the reported spot anymore.

 

[mathystuff]

Race tracker shows holcim just passed Malizia, which is still looking for penguins down south.

 

[Broadside]

Lots of people viewing this thread right now - are we all waiting to see what the story is with Malizia??

 

[noaano]

Race tracker shows holcim just passed Malizia, which is still looking for penguins down south.

Mutiny on board? Foil gave up?

 

[sunol]

Malizia must be causing a lot of anxious moments for all the navigators. 11th Hour doing 12kts and that will likely only drop more.

 

[ct800]

The interesting thing about Malizia is that their gybe angle was not the usual ~90 degree, but truly almost a turn back. Also they are having speed as of the Grafana dashboard, so likely no problem. Seemingly they have run into a hole. (Boat speed fell from 10+ range to 4-5 knots just before the gybe for about 10-12 minutes)

 

[minca3]

From their grafana page (https://exocet.cloud/grafana/d/bsbc...?orgId=15&from=1675939582921&to=1675960318922)

They seem to be back on track:

 

[Broadside]

The interesting thing about Malizia is that their gybe angle was not the usual ~90 degree, but truly almost a turn back. Also they are having speed as of the Grafana dashboard, so likely no problem. Seemingly they have run into a hole. (Boat speed fell from 10+ range to 4-5 knots just before the gybe for about 10-12 minutes)

They crossed behind Holcim within 3 or 4nm after being on the current gybe for the best part of three hours, with a net difference in VMC of 25.5nm/hr. They either do [Edit: did - having just seen minca3's post] have a problem or they are doing something very brave strategically?

 

[climenuts]

Yea and I'm guessing 110+ dB at times from that. Loud. Would be interesting to get some noise dosimeters on board

Hugo boss had one during the Vendee. Rarely went below 100dB and was up to the 130-135dB range when they were going through the 45-50kt cold front at the start of the vendee.

 

[noaano]

was up to the 130-135dB range when

This one I find a bit hard to believe.

Decibel scale is logarithmic, that would be incredibly noisy, that would be in the range of jet taking of from aircraft carrier deck.

I know these boats are loud, but not that loud. That would cause instant permanent hearing loss very quickly.

Fire alarms are set to 120 dBA maximum. 135dB is 32x fire alarm maximum.

 

[Slark]

They crossed behind Holcim within 3 or 4nm after being on the current gybe for the best part of three hours, with a net difference in VMC of 25.5nm/hr. They either do [Edit: did - having just seen minca3's post] have a problem or they are doing something very brave strategically?

Perhaps trying to stay in the pressure, perhaps also working something else out. If you believe windy a bit more pressure to the south so there is that. Lottery getting across that high.

 

[Fabricensis]

Any of our routers have time to do a quick test what Malizias new course would mean for their finish time? It does look more like strategy than a problem

 

[damien]

Weather routing Feb 9th

Input

1. Windfactor set to 110%
2. Polars for Malizia, 11th Hour and Holcim-PRB powered up to 115%
3. Biotherm polars @ 110% unchanged and Guyot 2015 polars unchanged
4. GFS 0.25 degrees 1-hour interval(see red tracks)
5. ECMWF 0.4 degrees 3-hours intervals (see blue tracks)
6. Boat positions 1040 UTC

Output

Pic 1 has in OpenCPN the Brazilian Navy synoptic overlay 00 UTC plus SAT IR pic 0740 UTC overlay. Added GFS 00 UTC rain for identifying fronts and MSLP. Added Malizia boat position 0740 UTC. The St Helena HP is north. But will start moving east in the coming days. And dissolve off Capetown. GFS seemed to have an accurate cloud cover when comparing to the Sat IR pic.

Pic 2 has the Wx routing and table for 1040 UTC boat positions and GFS in red and ECMWF in blue. When comparing the blue ECMWF routing ETAs to the red GFS routing ETAs for boats all delta ETAs < 1 hour for the top-4 boats. Only exception is Guyot. ECMWF projects Guyot much more northern than the GFS. I doubt that they will try their luck far more up north.

The weather models currently disagree on where the LP zone will exactly be off Capetown, dissolving. Hence the different routing. A potential nightmare for the navigators imho. But GFS has a higher resolution and more intervals. So my money is on that for now. See pics 3 and 4.

Pic 1 The big pic
View attachment 573606

Pic 2 Wx routing + table for 1040 UTC boat positions and GFS in red and ECMWF HRES in blue
View attachment 573612

Pic 3 GFS
View attachment 573608

Pic 4 ECMWF
View attachment 573609

Hi Herman!
What are the dash line in the routing for?
Thinking to work with the polar it will be interesting to re-route the boat when the leg is finished with historical grib. They give the closest estimation of true wind the boat had.
You can download them for free at https://cds.climate.copernicus.eu/cdsapp#!/dataset/reanalysis-era5-single-levels?tab=form
Good evening

 

[Kalimotxo]

Perhaps trying to stay in the pressure, perhaps also working something else out. If you believe windy a bit more pressure to the south so there is that. Lottery getting across that high.

Nico Lunven explains that he never wants to be the windward boat...

 

[Oxon]

We observed Malizia's light air struggles earlier on this leg. Sail inventory clearly played a role back there. Maybe a similar setup here but breeze may come forward more. That, in addition to the extra weight of Malizia may make Wiill Harris less tolerant of the risk of light air.

Seems like a strategic move that they wanted to be on the southern side of the fleet.