Automated Weather Routing—Part 1, The Tools

In the 2008/09 Volvo Ocean Race (VOR), Ericsson 3, skippered by the legendary Magnus Olsson and crewed by a relatively young and novice group of all-Nordic sailors, beat the odds and led the fleet around Cape Horn and into Rio, winning what at the time was the longest leg in VOR history: 12,300 miles from China to Brazil, much of it in the Southern Ocean.

They accomplished the feat by closely monitoring the weather, and adjusting course around it. 29-year-old Norwegian navigator Aksel Magdahl took a flyer and routed Ericsson 3 right through and around the top of an ugly depression west of Cape Horn.

None of the other boats followed. Ericsson 3 beat and bashed their way NE, patiently ghosted through the calm center of the gale. They were spit out the other side on a rip-roaring reach, ahead of the rest of the fleet who’d stayed south, rounding the Horn in first place and holding that lead all the way to Brazil.

Theirs was a brilliant and gutsy move, one that immediately catapulted Magdahl into notoriety, and which put perhaps the biggest smile of his career on the face of a weathered and bearded Magnus Olsson when they reached port and popped the champagne as the winning boat.

Weather routing has long been rooted in racing, and it’s historically been expensive. But lately, the tech is becoming cheaper and more accessible to cruising sailors. On long ocean passages, the tools we use aboard Isbjorn to predict the weather and adjust our route accordingly are not unlike those that Ericsson 3 used on that Cape Horn leg, and though the stakes aren’t as high, the thinking is much the same.

How We Sail and Why

Southbound in the ARC Caribbean 1500 rally.

We like to sail Isbjorn, really sail her, and we’d rather contend with heavier weather (to an extent) than have to motor through a calm. I plan our departure dates with this in mind, and likewise make course adjustments en route accordingly.

Furthermore, we’ve experienced, and are prepared for, heavy weather, so we can be slightly more aggressive in our passage planning. [Andy also sails with a relatively large crew, which makes heavy weather much easier to deal with than for a couple. Ed.]

Finally, we carry the big sails too, and with Isbjorn’s extra-tall rig, can usually manage to ghost along at 4-5 knots when most others are motoring.

That said, the tools and techniques I describe below can be used just as effectively to avoid heavy weather. If you’re going offshore sailing you’ve got to be prepared mentally & physically to deal with it when the going gets rough, but you don’t have to go looking for it like the Ericsson 3 crew did.

Forecasting or Routing

There’s an important distinction between weather forecasting and weather routing. The former provides information; the latter provides information with advice. We use a professional forecasting service (details on this in Part 2), in addition to downloading free GRIB files, but I don’t employ a router per se, preferring to make course decisions on our own.

Unlike the Volvo sailors, we can’t pick our weather beyond a departure window—Isbjorn doesn’t sail fast enough to route around weather systems. But with enough information and foresight, we can avoid the worst gales, slip past the biggest calms, and generally feel much more in control of our weather destinies than at any time in yachting’s history.


Isbjorn is simply outfitted, as I outlined in detail in that third refit article. Our primary navigation tool is an iPad, receiving GPS & AIS data wirelessly via a ‘blackbox’-type Vesper XB 8000, and running the following software:

  • Weather4D 2.0 (4D) (with various hydrographic office raster charts—more on this in a sec).
  • iPolar to create & import your boat’s polar information into Weather 4D. [Be aware that the polars produced by iPolar are are a very crude approximations of the boat's true performance and that relying on them without recognizing their limitations (I'm sure Andy knows this) may produce deeply flawed routing results. Eds.]
  • YB Connect (our YB tracker’s app).
  • XGate (for satellite email, connected to our Iridium 9555 handset via a Red Port ‘Optimizer’ wifi router).
  • Vesper WatchMate app (the dedicated AIS app bundled with the XB 8000)
  • Paper Charts for all primary (planned) destinations with appropriate plotting tools and redundant battery-powered GPSs. [This is an important point. Andy can safely sail with a navigation system that has many potential weaknesses and failure modes (iPad, WiFi based) only because he has the gear and skills to immediately switch to paper based navigation if required. Eds.]
  • A Tamaya Sextant with up-to-date nautical almanac & HO 249 Sight Reduction Tables for Air Navigation (mostly for fun!).
  • iNavX (with Navionics vector charts).

No Plotter, All iPad

The GPS on our Garmin multifunction display that came with the boat (over ten years old now) finally gave up the ghost this past summer. I didn’t bother fixing it. So while the radar still functions, the chartplotter doesn’t.

This coming winter we’ll remove the MFD and instead install a dedicated, stand-alone Furuno 1835 Radar (per AAC’s advice), and buy an iPad Pro (the larger screen version) for redundancy, which will be mounted at the nav station while the smaller iPad remains portable.

Let's dig in to how we use all of this at sea:

Andy Schell is the co-founder of 59º North Sailing, which takes paying crew on offshore sailing passages around the Atlantic, Arctic, Caribbean and beyond. They are currently refitting the Farr 65 FALKEN as their new flagship, while they operate their Swan 59 ICEBEAR and Swan 48 ISBJORN in the meantime. Andy founded and hosts the ON THE WIND sailing podcast and recently launched the online seamanship platform The QUARTERDECK. Andy has sailed over 100,000 miles offshore, including 5 Atlantic crossings and an expedition to 80º North in Svalbard in 2018. Check them out at

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