Weather routing electronically

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Simon Currin - 14 Feb 2021
Dick - 14 Feb 2021
Simon Currin - 14 Feb 2021
But Dick the electronic routing is not hard to repeat underway. When new routing is required all the processing of the raw data takes place on the provider’s severs meaning that this is more data efficient than bringing in a grib. The difference is that the raw data is coming from multiple models with huge computing power to process big data and present the user with real-time summary data which downloads very quickly.


Dick - 13 Feb 2021
George.Curtis - 12 Feb 2021
Simon Currin - 26 Sep 2018
PredictWind does it for us and they have recently become sellers of IridiumGo airtime which makes it easier to save money on Iridium costs if only using it part time. They have made significant changes to their tracking map too.

PredictWind provide methods to add positions to any of their tracking maps using Iridium Go, YB, Inreach, email, or via the PredictWind Offshore App on any connection type, including land based internet. PredictWind offer a 20% discount (rebate) on Forecast subscriptions to OCC members.

During the summer of 2020, PredictWind worked closely with the OCC where Daria Blackwell had assembled a list of boats intending to cross the Atlantic (See Flying Fish 2020-2). PredictWind provided a fleet tracker for the group. This service is now available to individual and groups of yachts as part of the PredictWind weather tracking and routing service.

Hi all,
I would add a caveat to all use of routing programs.
Say, one is leaving New York for Bermuda (a usual 4-7 day trip). I would suggest the skipper work the route on one’s own using wind & wave wxfx forecast charts, gribs, recent current charts (including meanders in the Gulf Stream), with particular attention to where the forecast wx/winds might be different from those forecast (say a low traveling a few hundred miles different south of forecast 3 days hence, a not uncommon occurrence which could change things dramatically). All the while weave in your knowledge of the likely daily runs (using ship’s polars if available and proven accurate to you and your ship over previous passages: too many polars are based on a boat’s numbers when racing).
Then, and only then, run your routing program and compare the results of the computer’s algorithms with your routing results, paying especial attention to discrepancies. Try to learn from the discrepancies as it is far from a given that the algorithms are wrong.
In this way, you will be far better prepared to adjust to changing conditions, especially if the electronic routing is hard to duplicate underway.
The above suggestion is akin to knowing traditional navigation techniques (dividers, parallel rules, paper charts etc.) as the under-pinning for knowledgeable and safe use of electronic charting.
My best, Dick Stevenson, s/v Alchemy

Hi Simon,
Even if the routing is able to be done underway, that in no way undermines my suggestion that the skipper will benefit from doing his/her own routing. Having a hands-on approach gives a depth of feeling for the route chosen, the weather expected and the various possibilities that I suspect relying on algorithms does not come close to. It is only after working one’s own route, that I suggest reviewing a route based on algorithms. They will hopefully be very close: if not, there is work to be done understanding the discrepancies.
In the early days of electronic charting, careful skippers also worked their piloting choices on paper charts using dividers and parallel rules. Over time, electronic charting has proven itself pretty reliable and, probably most important, some of the “glitches” that can occur with electronic navigation, have become clear and well known.
I suspect that electronic passage routing will eventually reach a level of accuracy and reliability where, like electronic navigation, most skippers will rely on the algorithms and, I will hope, they do not do so blindly, but will have the experience of traditional routing techniques to enrich the experience and to back them up.
My best, Dick Stevenson, s/v Alchemy


And, Simon, thanks for the fill about the possibility and ease of re-doing the routing when underway. I suspect this will just get easier and easier. Dick

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