Atlantic Weather Routing

PlankWalker

PlankWalker

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I am providing weather routing for an Atlantic circuit. It's all been pretty easy so far with the East to West trade wind route, but the return from the Caribbean to UK via Azores has now started and is more challenging.

Although I find Ugrib files and metiogrames very good, it's dificult and time consuming to put their various E.P.'s on the grib chart for 3, 4 or 5 days ahead, as the grib charts have little navigational information on them, no scales or bearings etc.
How do other people do this?

Plank
 
PlankWalker said:
I am providing weather routing for an Atlantic circuit. It's all been pretty easy so far with the East to West trade wind route, but the return from the Caribbean to UK via Azores has now started and is more challenging.

Although I find Ugrib files and metiogrames very good, it's dificult and time consuming to put their various E.P.'s on the grib chart for 3, 4 or 5 days ahead, as the grib charts have little navigational information on them, no scales or bearings etc.
How do other people do this?

Plank
Click to expand...
Try opencpn. The grib plugin is good and you could create a route of where you expect the boat to be in the next few days. I did similar on a recent Biscay / Span-Portugal trip with waypoints named "+12H", "+18H" etc marked at an estimated speed then flick through the gribs which were downloaded offshore with a ham radio transceiver.

http://opencpn.org/ocpn/downloadplugins

The weather routing plugin may well do much more for you, haven't played with that yet.

grib-visualization-05.jpg
 
Can't help thinking this might have been a good question to ask before taking the gig.

However, if you're going to use a routing program, you need to have a good get of polars, without which the software cannot work.

Otherwise, just load the grib into OpenCPN (or your program of choice), and set up waypoints at the relevant positions.
 
GHA said:
T...The weather routing plugin may well do much more for you, haven't played with that yet.
Click to expand...

OCPNs routing plugin is neat, it not only uses the current GRIB but also makes use of the historical wind/current rose average information. So for a 20-25 day typical W-E crossing it'll give a baseline starting route. The harder task is then overlaying that with dynamic changing weather and trying to work out whether a yacht can actually move fast enough to avoid oncoming weather. I'd try to apply the sort of thing Frank Singleton refers to as a confidence factor, so if the GRIBs are giving roughly the same outlook over a series of model runs you can be fairly sure the outlook will be as predicted; where those outlooks change rapidly, so will the weather. There is also a weather fax plugin for OCPN that can overlay the chart on a wide area, what would be interesting is comparing GRIB with fax overlay.

Edit: Yes, polars are required for routing. Its possible to create a baseline using the tools in the plugin then tweak it if you think the boat will behave significantly differently to the polar predictions.
 
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Thanks for the advice guys. I have managed to get Grib onto the OpenCPN basic chart which is a great improvement, I can now navigate!
Even better would be to get a decent Ocean chart onto OCPN showing a bit more detail. Is there a free one I can download anywhere.

Plank
 
RobbieW said:
OCPNs routing plugin is neat, it not only uses the current GRIB but also makes use of the historical wind/current rose average information. So for a 20-25 day typical W-E crossing it'll give a baseline starting route. The harder task is then overlaying that with dynamic changing weather and trying to work out whether a yacht can actually move fast enough to avoid oncoming weather. I'd try to apply the sort of thing Frank Singleton refers to as a confidence factor, so if the GRIBs are giving roughly the same outlook over a series of model runs you can be fairly sure the outlook will be as predicted; where those outlooks change rapidly, so will the weather. There is also a weather fax plugin for OCPN that can overlay the chart on a wide area, what would be interesting is comparing GRIB with fax overlay.

Edit: Yes, polars are required for routing. Its possible to create a baseline using the tools in the plugin then tweak it if you think the boat will behave significantly differently to the polar predictions.
Click to expand...

:sleeping:
 
PlankWalker said:
Thanks for the advice guys. I have managed to get Grib onto the OpenCPN basic chart which is a great improvement, I can now navigate!
Even better would be to get a decent Ocean chart onto OCPN showing a bit more detail. Is there a free one I can download anywhere.

Plank
Click to expand...

Once you set off from the Caribbean direct for the Azores you only really have two choices as the weather varies. Go East of go North. The weather will do what it wants and you will be doing somewhere in between East and North as it does. Take a lot of fuel for this route as wind can be very light at times
 
PlankWalker said:
Thanks for the advice guys. I have managed to get Grib onto the OpenCPN basic chart which is a great improvement, I can now navigate!
Even better would be to get a decent Ocean chart onto OCPN showing a bit more detail. Is there a free one I can download anywhere.

Plank
Click to expand...

Once you set off from the Caribbean direct for the Azores you only really have two choices as the weather varies. Go East of go North. The weather will do what it wants and you will be doing somewhere in between East and North as it does. Take a lot of fuel for this route as wind can be very light at times
 
geem said:
Once you set off from the Caribbean direct for the Azores you only really have two choices as the weather varies. Go East of go North. The weather will do what it wants and you will be doing somewhere in between East and North as it does. Take a lot of fuel for this route as wind can be very light at times
Click to expand...
Bit more choice if you go North first imho, watching weatherfax when you strat heading East 50 odd miles further north or south can make a big difference depending on the track of the lows.
 
One weather site not mentioned so far is Passage Weather:
www.passageweather.com

They generally seem to be pretty accurate.

And there is no point in trying to get too fussy - as the above posters have mentioned, it is a balancing act to stay on the edge of the High, without losing the wind, and avoiding running into hurricanes.

We crossed from Barbados to the Azores 4 years ago, and Lenseman David of this parish kindly supplied us with weather routing - David had an amazing ability to tell us what to do in (I think) less than 150 characters for texts received on the sat phone.
We received a classic text one morning - sailing north'ish at 10 - 12 knots (this was on an 80' Maxi) with the spinnaker up, calm sea, all is well, David texts 'Stop! Turn right now. Hurricane ahead.'
So we hung a right, lost the wind totally for a while, complained a bit to Aeolus, but were later very grateful after we met other boats in Horta who were less than 100 miles ahead of us who had been well pasted by this hurricane.
 
Have always taken a pasting on the route apart from once. Left well into June due to a. wanting to watch champions league final and b. Boat broke two days out of Jolly Harbour and had to sail back for repairs to fracture in forefoot of hull.

Had a cracking trip after that, well, until exhaust blew needing a divert to Azores rather than the planned non stop to Lanzarotte.

Its still abit of a lottery but should the chance come up again, June too soon works for me.

Happy voyaging.
 
Hi,

I always stress to clients that we do not 'weather route'. I will provide weather information and advise on what's north and south, but 'routing' is a very, very dangerous game.

Be very careful what you are allowing yourself to be liable for, especially if you have not prepared beforehand and are now asking additional questions. I certainly do not want to doubt your abilities but are you a qualified forecaster? Do you have experience to offer 'weather outing'. Do you have Professional Indemnity Insurance?

If you are not getting paid then I guess that absolves you from many potential pitfalls, but not from everything.

My advice is give the weather information as it is, leave it to the crew on board to decide which route to take!

Hope that helps and advanced apologies, I don't want to worry you,
Simon
 
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