Weather Window

Sailing a north – south course in pursuit of an efficiency challenge, has its own inbuilt challenges.

As weather systems generally move west to east around the world, a southerly course means crossing weather patterns rather than ‘riding’ them as so many other ocean challenges do.

One difficulty in picking a weather window for tracking from Brisbane to Hobart is the inability to deviate far from course in order to be best placed for weather systems such as highs and lows, as other ocean passages in pursuit of records allow. Heading south, the bulk of Australia is to the right, precluding deviation in that direction.

Too far to the left of the rhumb line course and as the boat turns back towards Tasmania the track then becomes more into the oncoming weather.

Because the Roaring Forties experience processions of cold fronts (hence the varying weather and winds) it is difficult to find a 3-4 day period that excludes the passage of a front, without having had to have fought headwinds on the mainland coastline on the front of a high pressure system, or the back of a just-passed cold front.

In order to try and avoid prolonged headwinds, one option is to steer through the weakest possible part of the front and into the oncoming high as quick as possible.

Our departure on Thursday morning will see us motor down the Qld and northern NSW coast under the influence of a ridge of high pressure. While the boat is still heavily laden with fuel and supplies, we expect the sea state to be kindly and thus enable us to keep a high average speed while in ‘heavy’ mode.

BOM chart issued 4.00 am 21 Feb 2004.

In the middle of Friday we anticipate driving through the weakest tip of the cold front on the southern NSW coast, receiving some shelter in the lee of the mainland while the attendant SW winds moderate and back around. This could well be the roughest part of the journey but should position us well for Bass Strait. View current weather chart. Saturday’s crossing of notorious Bass Strait is expected to be in light winds as the high pressure system becomes established over the area (perhaps even northerly winds according to BOM long-range forecasts), in a segment of the voyage where we are most exposed and furthest offshore. [Refer latest news of economy trial progress.]

Arrival in Hobart is planned to be early Sunday morning before the next cold front associated with a low pressure to the south arrives over Tasmania.

Watch our progress map on this site regularly, and compare to the actual weather experienced as we head for Hobart.