Sunday, 29 March 2015

VOR 2903 - Let it rip!

800nm to the Horn, and will be one hell of a ride...

Looking at the 0040z sched, there is nothing in it, with the exception of SCA1 who have dropped off the train, and may be punished for this with their slightly N and W position as the front rolls in.
Nothing in it
ADOR and TBRU are registering as 12nm DTL, however are set up to the S and W of the leaders and as the routing results suggest this is negligible in terms of time to the mark at CH.

0040z run, GFS model

Point it at the mark and let it rip



The rest of this portion of the leg is going to be all about sailing minimum miles (with the exception of SCA1).

The first boat to Cape Horn is going to be the one who can keep their foot down and not trip over it as the VO65 appears prone to do.

One wipeout at 20kt boatspeed is a loss of between 10 and 20nm.

Keeping the rig pointing at the sky...

Chinese Gybes were a hot topic last week, and this week will possibly be even hotter. However the rest of the leg looks like sailing hot angles rather than VMG mode which may be better for keeping the wet bits under the boat.

The dynamics of these boats is very different to a conventional yacht. The VO65 keel pins are slightly off axis (4deg from memory) - so at full cant the leading edge of the keel is tilted up. This is a performance enhancer - reducing displacement (think foiling but only about 1% of the way there). A side effect is reduced righting moment.

Rob G's comments after the MAPF wipeout was it happened ploughing into the back of a wave. Imagine the scenario with surfing down a wave, the rapid deceleration at the back of the next one...and a keel canted out to weather

  • The boat parks in the wave and decelerates
  • A ~6T bulb canted out to weather wants to keep going - spearing the boat off to leeward
  • Apparent wind speed spikes & angles changes instantly
  • Righting moment and displacement change due to the canted keel 'tilt'
No bloody wonder they are hard to hang on to. Wouldn't help if the rudders are too small or not very 'grippy' - not suggesting they are...

Weather

The boats have a cold front approaching from the W. GFS model suggesting sustained 26-30 kt. My bet is this will be 30-40, possibly +20% with gusts, and if the front itself catches up then potential for a lot, lot more.

However, doubt the boats will be going any faster in 40 than in 30. In fact maybe slower.

No accounting anywhere here for waves/sea state etc...

Here is a run, with the cold front evident in the second half with the predicted rain highlighted.

Thursday, 26 March 2015

VOR 2603 - a whole lot of ocean

Middle of nowhere, but nowhere to go

The fleet is banging off of the edge of the ice exclusion zone which must be maddening for the teams, however they will be released soon from this virtual fence...but will be interesting to see where they go from here.

Routing over the last couple of days has suggested that a NE route is fastest to the Horn, however not by a great deal.

1840z pos, GFS

The SCA1 route in timing terms gets them into CH with pretty much the same time deficit as they currently have - however sail fewer miles. Probably more maddening miles though sailing 1000nm down the edge of the exclusion zone.

For the leaders, the SE route is only 3hr slower in theory than the optimal NE route. I expect to see the fleet juggle themselves somewhere in the middle of the two options, playing it safe and conservative.

Results to CH

Roller coaster ride

The two options are driven by quite different systems. NE to tap into the back of a L system, SE to hook into a cold front.



Running hard

Route output shows a fun ride for all...
TWS down, TWA across. Data in hours.

Wednesday, 18 March 2015

Expedition Seminar

I will be hosting a seminar in Lymington, focused on the features and functions of Expedition Navigation Software.

Download information here.


Monday, 16 March 2015

VOR Leg 5 - T-2 (again)...Should I stay or Should I go now?

Big brother meddling

So the Start of Leg 5 has been shifted out bit by bit. Initially prudent I believe with the uncertainty of the impact that STC PAM could have had on the fleet. I doubt a single person would deny that it was a good idea to wait and see how it panned out since a scenario could have arisen whereby the boats had no escape route.

Am sure there would have been a full consensus amongst the competitors that this was the right thing to do

However, IMHO, this power (that of the RC) has been taken too far by delaying to Weds (NZT). Now the fleet could potentially face what may be boat breaking conditions, without much wind to speak of.

As soon as the centre of PAM had passed the approx Lat of Akl or at least East Cape, the boats would have plenty of sea room to be the masters of their own destiny. Get N and diverge from the system for less winds, or charge on in and hang on for dear life. At the sole discretion of the skippers.
Findamental rules of the RRS


PAM, where has she gone?

Screen shots below show a start point at Coromandel, for ease of running the route. This is ~45nm from Akl, so even ignoring the dog and pony show loops around the harbour the boats would take a while to get to the 'start' of my routing.

Start -24hr...nice breeze out of AKL

Start -12hr...still not bad out of AKL

Start...mmmm...bugger, missed the train.

Start +12. Still sitting at the station. 

What does the rest of the leg hold?

Not entirely clear, but the navigators will have their work cut out this leg, with the first corner some 4500nm away.

At the preset times for the weather files downloads, the send/receive button will be getting pretty hot, the guys willing the files down over the FB units. Anyone with comms issues on this leg will be at a serious disadvantage.

High pressure, MSLP or BP?

Out the back of PAM an expansive H region establishes. Going to have to push hard, very hard to try and stay in touch with PAM. Anyone who gets across the H well and manages to stay on the back of PAM will take off. Get dropped, and you are toast.

The H could be a big part of this leg

What will the future hold?

Reasonably uncertain for the 2nd 2/3 of the leg. Don't wear out those send/receive buttons boys.

GFS (red) and GEM (blue) Ensemble plot 7 days from now

Whole route...

Not sure the image below is of much value. Two wx models disagree. Will just have to wait and see how it plans out. Lets just hope the AIS tether gets broken early and se can see some more freestyle Ocean Racing Navigation...

The GFS (American) model - might need to check the sunscreen stocks. GEM (Canadian) model, not as afraid if ice.

Tuesday, 10 March 2015

VOR Leg 5 - T-5. This is was what was in the brochure

Record breaking or boat breaking?

A very quick review of Leg 5 weather outlook and the fleet could be in for one hell of a ride...

TC PAM coming into the mix so early on in the leg will sort the men from the boys. 

Expedition run GFS

Quickly looking at the transit across the top of PAM, one 24hr period reveals a potential 675nm run from point to point - not distance covered over the ground but a straight line between two points.

This is not necessarily achievable as the polar is suggesting sustained speeds of 25-35kt, no account for crashes, there is a gybe in the mix and Sig wave height at the position of the screenshot below is over 9m.
Transiting PAM, a record?
Significant Wave Height

Statistics

~60% of the leg to the Horn is sub 25kt, but what is more interesting is that ~60% of the leg is at TWA125 or wider. Thats what you sign up for in this race!


Testing the routing

Re running the opt route with a spread of TWS and Polar % reveals the dominant effect of PAM in the first half of the leg, the second half is to be fair too far out to draw any conclusions.

Route options with a spread of TWS % adjustments. 



Route options with a spread of Polar % adjustments



Finally, what impact on routing has the Ice Limit had?

The Ice limit looks like a get out of jail free card, but limits the routing options. With the limit in place the fleet is 'forced' to go over the top of PAM. Without the limits, fastest route is S, a long way S...but only a couple of hours in delta at the Horn.

Even without the lice limit, I know which way I'd go...





Wednesday, 4 March 2015

Caribbean 600 - SORCHA

Charging around the Caribbean...

Raced the 2015 RORC Caribbean 600 on the recently modified TP52 SORCHA. A fun project with a great bunch of guys.


We had a sensational battle with the highly successful Tonnerre racing team, with their new Ker 51 fresh from a win at Key West Race Week. Having a very similar typeform boat, albeit with the Ker 51 being more IRC oriented, made the race for us and pushed us harder and generated a great deal of team focus.

The highlight of the race was possibly one of the best days of racing I've ever had, running in 20-22 kts and a gybing duel with Tonnerre as we neared the bottom of the run...



Expedition track of the run with winds

The lead changed no fewer than 5 times in the race, with SORCHA cementing a lead in the transition through the lee of Guadeloupe. We had a very good passage through the lee, again putting my faith in the Predict Wind high res models, and proving yet again to be uncannily accurate.

I exclusively used Predict WindExpedition Software and TideTech for this event.

Track w/winds through Guadeloupe, winds 1km resolution from Predict Wind

Great result

As the chafe and sleep deprivation fade, the satisfaction of an overall 2nd place in IRC, 2nd in IRC zero and CSA made the hard work worth while.



World class crew





Monday, 16 February 2015

VOR 1602 - back to the grindsotone

The excitement is over, get back to work

Seems TBRU have decided to cash in and step back in line with the fleet. Fully understandable and ultimately a smart move as could have been too easy to get greedy and come home with nothing.

They now have a handy ~67nm lead over ADOR, but makes it bloody boring for the rest of us armchair critics now. I was genuinely excited when TBRU and SCA1 stepped up a week ago.

The 1855 posreport references to a fictitious mark again, approx where the routing takes the fleet, however DTF is now approx the same as it is to AKL. Of note is the loss in the last 6hr to ADOR, due to reported less pressure and a 10deg finer TWA.


Optimal route options

Todays run with the 12z GFS at 0.25d shows a far narrower finish margin than when the gauge across the fleet was significant. Back to a dogfight and an AIS interrogation. Must be just like playing the VOR game for the navigator...

Route is pretty straight forward, however I feel will not be as simple as it looks...there are some serious disturbances in the region from approx 5n to 23s, and still looking like a very light ~1000nm to get across before tight reaching into Aotearoa.

The route has a 3hr time sensitivity shaded, quite a narrow corridor which will not do anything for the excitement for us over the next 2 weeks...













ITCZ doesn't look like much now...but the first bank of tropical cloud is less than 300nm in front of the fleet...

Finally, a video of the run...