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A Most Difficult Ocean Passage Coming Up – Playing The Weather Odds In Hurricane Season

Friday March 14 2014 NZ FCast

The passage between New Zealand and French Polynesia is one of the more difficult ocean crossing endeavors. At 2200 miles along the great circle route, it can often be as long as 2600 or more nautical miles depending on weather routing. John and Amanda Neal bill this as a heavy weather passage in their sail training business, and for good reason. FPB 64-6 Grey Wolf is on standby, waiting for a weather scenario that offers decent odds. The chart above is for Friday, March 14th, and is not what you’d call auspicious. This is the first leg in her voyage back to the old world and her new home in UK’s Channel Islands via Panama.

FPB 64 Fray Wolf routing to Tahiti 1

Here is a look at two of the course options. The red line represents trying to minimize headwinds, and then when Tahiti is a fetch, angle wise, making a left.

This is late summer in the Southern Hemisphere, which means several things. One is that the South Pacific high pressure system is in its position furthest away from the equator, which brings the easterly trade wind belt south and directly in Grey Wolf’s path.

To make things more difficult, the cyclone season is just ramping up. The official forecast for El Niño, which gives a higher cyclone probability to French Polynesia, is neutral. But the current activity (see below) suggests something is afoot.

THur March 21 2014 SP Wthr

 

Here is the GFS forecast for next Friday. That’s another tropical event transitioning to extra-tropical, shown halfway along the path to Tahiti.

There are a few things to take into account with all of this.

  • Average boat speed is a critical component of planning. Whatever the number might be in smooth water, it is going to be less, possibly a lot less, given the headwinds and confused sea state that is likely to be encountered.
  • With the trades blowing strongly in this region, the westerly current flow will rob you of 12 to 24 miles a day of progress.
  • Forecasting tropical weather is much more difficult than that of the higher latitudes. The models do not perform as well. In the Atlantic there are more resources focused on hurricane season – satellites, aircraft, ground and ship observation – than in the sparsely populated South Pacific.
  • In some situations you can cross an active hurricane area quickly, such as Palmyra in the Line Islands to Hawaii. But between New Zealand and Tahiti the course is parallel.
  • Tropical weather can be helpful in that it knocks down the trades – if you are heading against the wind.

We have made a number of passages crossing hurricane belts in season where we had the speed to make use of their benefits. Nuka Hiva in the Marquesas to San Diego, 2700 miles normally uphill, comes to mind. Here hurricanes were beneficial (to see a video on this passage click here), helping us cover the 2700 NM in just 12 days.

We have done the New Zealand-Tahiti run twice. The first time was under sail with the 68-foot Sundeer, leaving ahead of cyclone Bola in summer of 1988 – which hammered New Zealand, arriving in Tahiti a day after a small tropical disturbance created local havoc. The second time was with the 78-foot ketch Beowulf, via the Austral Islands. That was in 1997 and the weather patterns forced us to sit in New Zealand for a month waiting for decent conditions to depart. A video of this passage is here..

FPB 64-3 Iron Lady made the Tahiti passage last year. But she left later in the season (you can see her posts here).

All of which is to say this can be done, but it won’t be easy.

NZ Gambiers

There is another route to be considered. Although the crew would like to experience the attractions of the Society and Marquesas Islands, if they are forced to take the sailing route, they can also look at heading to the Gambier islands at the bottom of the Tuamotus. This keeps them further south, is the same distance as Tahiti via the dog leg course, and has the potential of less exposure to tropical weather issues with reduced headwinds along the way.

When Grey Wolf departs they will be pressing the boat hard to keep speed up. The crew will definitely earn their sea-going stripes. They will want to have a polished hull and prop, and keep the boat light for speed rather than comfort. And they will be getting outside weather routing help. With all of this they are also going to need some luck.

For more data see:

www.passageweather.com

Our books Surviving the Storm and Mariner’s Weather Handbook cover these situations and much more.

Peter Watson and crew will be reporting on their trip on the Berthon website here.


Posted by Steve Dashew  (March 14, 2014)




9 Responses to “A Most Difficult Ocean Passage Coming Up – Playing The Weather Odds In Hurricane Season”

  1. Brian Rickard Says:
    You may have already had other comments about this, but the underlying link you give for ‘www.berthon.co.uk/greywolf’ is, at the time I’m writing, actually a concatenation of that and *this* article’s URL.

    [Reply]

    admin Reply:

    Oops! Fixed it–thanks Brian!

    [Reply]


  2. Chris Says:
    In case you haven’t seen this: http://earth.nullschool.net/

    [Reply]

    Steve Dashew Reply:

    Thanks Chris: That is a great weather pattern indicator!

    [Reply]

    Warren Cottis Reply:

    Hi Chris & Steve Do you know who owns this site please?

    [Reply]

    Chris Reply:

    http://earth.nullschool.net/about.html

    [Reply]

    Chris L. Reply:

    http://www.noonsite.com/images/pdfs/south-pacific-weather-resources

    [Reply]

    Warren Cottis Reply:

    Thank You

  3. Alan Leslie Says:
    Interesting….we left Auckland in May 2014 headed for Raivavae, 2 days after John Neal left. John went north around the top of a low pressure centre that was heading south from Fiji. We went fast, almost due east trying to get in front of that low…almost made it, but not quite, we had to turn north in the winds we had, until the low passed behind us…we had 50+ knots for 2/3 days. Once it passed we headed back on course for Raivavae. 2367 nm and 14 days out of Auckland, we were at anchor inside the lagoon preparing to meet the Gendarmes. Cheers Alan S.V.Elyse

    [Reply]



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