PredictWind Weather Forecasting & Routing Review | Sailing Blog - Technical Hints and Tips - Sailing Television

PredictWind Weather Forecasting & Routing Review

How can you get weather updates while at sea? What is the best day to set sail on a passage to get the best conditions en route? How do you choose the route for the fastest and most comfortable passage?

Getting good weather information at sea used to be one of our biggest challenges over our 26 years of cruising internationally. That has changed dramatically this past year as we have been testing PredictWind.
PredictWind is a subscription weather routing service that integrates with the IridiumGO satellite communication network. As we were doing over 6,000 sea miles and 2 transatlantic crossings this year it seemed a good time to try it out.

Although PredictWind can be accessed through a website, what caught our attention was their IridiumGO interface and app. This means we can access weather forecasts and routing information while we're at sea using the IridiumGO unit.

We run the PredictWind app on our Mac laptop connected to the IridiumGO by wifi and ask to download a forecast. It takes a couple of minutes to connect and presto - we have downloaded a GRIB with the weather and routing data. The app has a very good GRIB reader so you can immediately check out the PredictWind forecasts.

Multiple Forecasts

A feature for the true weather aficionados - PredictWind uses four different weather models. GFS CMC and two special PredictWind algorithms. I have been using them to compare and average the forecast models. Having the side-by-side display of the different weather models definitely helps raise your confidence in the forecast, or make you aware if the different models are disagreeing. A very good feature!!
(note in the lower left the key for the 4 models with the PWG forecast route highlighted in blue)

Weather Routing

Getting weather and GRIB files at sea is great but then you need to work out the best route for a fast and comfortable passage. For most of our 26 years of cruising I have done the job myself, "guesstimating" our performance and stepping off our daily run on the paper chart (remember those 😀)   

Nowadays sailors have a couple of options: 1) Retain the services of a professional weather router who can email, phone or radio you with daily reports and suggestions or 2) use PredictWind to do the routing with their powerful computer and send you reports on demand. We've been testing PW routing this season and it's been excellent.

To calculate a route you need to know how fast the boat will go given different wind strengths and headings. PredictWind lets you put in a custom polar table for your boat, or choose from a number of tables they have already set up. Then when you want a route suggestion you just click on your start and destination and input your planned start time. The PredictWind central computer sends back a detailed report with suggested routes for each of the weather models and tables showing the conditions to be expected along the way. The file they send back is very small - just a few KB - so it's easy to receive at sea over satellite or SSB pactor.

Here's a sample of our passage routing file from the leg across the Atlantic. Depending on which weather model is used, we might expect to take 12-13 days. Of course weather forecasts 2 weeks out are not going to be that great, but we are updating it at sea whenever we want! Nice.

Departure Planning

Looking for that "weather window" for a tricky passage? When should you set sail to get the fastest or most comfortable passage?

Running through the scenarios for the best departure date used to take me awhile and was a bit of a rough estimate, as I would quickly step off estimates of our daily runs given the weather forecast. PredictWind has a great feature that does this for you! "Departure Planning" allows you to quickly compare a set of departure times and see what the passages would be like. In the example below we are comparing 4 departure dates a day apart - leaving December 8 at 12:15 and 24,48 and 72 hours after…
Note how it summarizes how much time will be spent upwind, downwind and the percentage of time in which wind strengths and swell heights….

Extra Features

In this review I haven't been able to cover all that PredictWind can do but before we finish, here's one nice extra for the cruising sailor who has a website (like us :-)
This is a nifty tracker page that PredictWind has coded. You can put it up on your website and the folks at home can see where you are. This uses an IridiumGO feature to track you, and PredictWind updates the positions on this map… and makes the folks at home feel better…

The Verdict

PredictWind is an excellent solution to the cruising sailor's basic need - reliable knowledge of the weather at sea. Plus it does a remarkable job of providing weather routing. Paired up with the IridumGO unit it is an amazing combination for the offshore sailor.

Read More

Check out the PredictWind website for more information here…
offshore-evening-sail - 1
How do you get your weather information when at sea? Have you ever tried PredictWind or used other weather routing systems? How did they work out for you? We value your opinions. Please leave your comments and/or questions below…

And please share with a friend you know who might enjoy learning about this weather routing system. Thanks!

You may also like:
IridiumGO! - Review for Cruising Sailors

Transatlantic Passage Planning

When to Abandon Ship

The O Words - Offshore, Ocean, Overnight

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