In this course you can learn about the mechanics of global weather, the foundations of ocean meteorology, predictive modeling and how sailors receive data via satellite and use high-performance navigation software. This course looks at oceanic meteorology and climatology through the lens of the sport of sailing. You will gain a basic knowledge of meteorology needed by sailors to take part in a regatta such as the Barcelona World Race, the only double-handed, round the world regatta with no stops. You will learn about the strategies employed during a round the world regatta and how these are put to use on board the latest ocean racing yachts.
Video 3.1.3 Route calculation
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来自 Universitat de Barcelona 的课程
Strategies for winning. Meteorology in a round the world regatta
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从本节课中
The sailor as meteorologist
In this module you will learn how sailors use meteorology to sail around the world and to win round the world regattas.
All of their interest is focussed on the wind and they need theoretical, but above all practical, knowledge to help them to take the correct decisions at sea.
Remember you can access to the help forum.
If you are experiencing difficulty learning or accessing course content, or if you simply want more information.
与讲师见面
Tomàs Molina
[MUSIC]
So we've had a look at these polar diagrams,
we've had a look at these GRIB files, now let's try to make a weather routing.
The main task of a navigator development we've got a program called ADRENA open.
You can see a chart of the world, well part of the world at least.
Barcelona World Race, we'll start here in the Mediterranean,
Barcelona, get out of Gibraltar and then we want to go south.
We want to go south, Barcelona World Race's the three capes.
Meaning Cape of Good Hope, Cape Leeuwin, and Cape Horn to port.
So we have to turn like this.
We want to get into stronger winds down here.
And the main goal here is to get into the stronger winds down here.
So let's first of all open the GRIB file, we've heard that term before.
There we go, a few GRIB files of today.
I'll do this one, one from the European Center.
I know it's a nice, ten-day forecast for the whole Atlantic.
All right, it just says where it's from, when it's starting,
which the variables are.
Only three variables, we don't need much more.
All right, and then I said OK.
Now it's open.
Over here we can see for when this picture is valid, all right?
And it's going to be valid for a lot of times.
It can be valid for all those times.
Ten days, three hour intervals.
But for the moment, it's valid for today, today, now.
Fairly typical situation, actually.
You see highs over here.
You can see the trade winds below it.
The Saint Helena high over here.
A little bit far south, but it's there, right?
You can see the southeast trade winds over here.
And the Southern Ocean.
This is the good stuff.
This is where we want to go.
See how close the isobars are together.
That's were the strong, favorable winds are.
We want to dig in to that, right?
So, how are we going to get there?
Well, it's pretty easy to see, I'll just draw that on.
It's pretty easy to see that the shortest route will be something like that.
All right, follow the coast.
Blah, blah, blah, blah, blah.
Stay really close to the coast.
And then once you turn the corner here, go straight down.
I mean that's where the finish is.
That's the shortest course.
Well, that looks all right, but it isn't.
It is the shortest course, but you can see here,
see how far the isobars fall apart here?
There is no wind here.
This Horn of Africa is a horrible place, there is no wind.
Then also Saint Helena high is here,
you can see all the winds are coming from the southeast.
Meaning upwind, meaning slow.
All right, so direct course would take you there.
Of course that, I'll take another course here.
A course that a lot of people know is quick, is sort of over here.
Try to get west as quick as you can.
Of course over here, it will get lighter, all right?
Go down Brazilian coast, more or less like that.
And be the first one to hook into the strong west lees.
And here, this is where the good stuff is.
This is where, when you hear about boats breaking 24 hour records,
this is over here.
Long waves meaning they don't slow you down, and strong winds, all right?
Massive detour.
This is where the weather routing's going to help us to decide how much of
a detour to take.
Do we go all the way around like this or
do we go closer in here, try to cut the corner?
That's what we're going to use the software for.
First of all, I'm going to get rid of this and
then I'm going to make a few way-points.
What is a waypoint?
A waypoint is a point along the way.
We can either go to the waypoint, or
we can leave it to the left or to the right, to port or starboard.
And it helps us to sort of give a shape to the route we want to take.
We know we want to go into the Southern Ocean.
This is a fairly good entry point.
Let's roughly aim at that.
It's not a point we have to reach, right, it's not like a mark in a port, or
something like that.
It is a rough place we want to go,
just to make the computer think that we want to go that way, more or less.
All right, we can move this later on, it's just a start.
So, on this waypoint, I know that if I start here, and
I don't have a weather forecast that goes all the way here,
the routing will probably send me over here somewhere.
So maybe I have to help a little bit and force it towards the west.
Right, so I'll put another waypoint in at the equator, where's the equator?
All right, here we can see 20, 0, 20.
Equator is here, and I think over here is a good start
to put a waypoint in, create a waypoint here.
You can see the longitude here is 27.40, all right?
A good crossing point just out of historical stuff is around 28 anyway.
The doldrums, the calm winds around the equator typically sort of between one and
five degrees north.
So maybe I'll move it up north a little bit.
So I'll put this into five degrees north.
North, and I'll stick it at, I'm pretty happy with that.
Let's give it a name.
The name I'm going to give it is Doldrums.
Okay, and I've got another waypoint.
So now to start, the weather routing,
I will have to tell the program that I want to go there.
So first of all, I need a starting point.
Normally, you'll have your boat somewhere onscreen.
But we don't have a boat since we're in an office here.
Let's put another waypoint over here, simulating that we just got out of
Gibraltar.
Clear to Mediterranean, which is a good start.
And let's call this waypoint, Start.
Okay.
Now we can get to the real stuff.
We've got a waypoint to start from.
We've got a sort of limitation to make sure we get into the equator and
the doldrums are in the right place.
And we've got something to aim for.
We've got something to aim for which is the entry in to the Southern Ocean.
The highway around the globe.
Right, so let's make a course.
Let's link these way-points together so we know what we want to aim for.
going to be a very simple course.
We're going to make one,
it's in this thing called Course Management.
Click on it and it will make a new, some people have dozens of routes here.
You can create one, you can modify it, you can simulate, you can save.
And we're just going to create one.
Create one so where do we want to go?
We want to go to the Doldrums.
Want to go to the doldrums.
That's in there.
We want to leave that to port.
To port is, if the boat's going that way, port is on the left,
so we want to leave that to the left.
So then we want to go to our next waypoint.
Our next waypoint is what we call the Southern Ocean Entry.
Southern Ocean Entry, and I'll just leave that to port as well.
Well I'll round it to port, it doesn't really matter.
All right, it's so
far away, it's two weeks away, we'll move it 100 times before we get there.
Okay, give it a name.
Let's call it Barcelona World Race.
And then I think we are all good to go.
Okay, I'll close this.
And now let's go this famous weather routing.
Right here, Weather Routing.
Lots of options here, but
it starts with the basic thing at the top Calculate the Routing.
Calculate a Routing, what do we have here?
Well, first of all, we've got the date, when we want to start.
Well today happens to be 25 of June, so we're going to start today, right?
Then it tells you from where do you want to start from?
Well, we want to start from the thing we called Start,
because that's the waypoint we just put in.
All right, where do we want to go to?
Do we want to go to a waypoint or do we want a course?
We want to do a course because we had two way-points, two points we were aiming for.
So here's the course, which we calls Barcelona World Race, I go OK,
and there we go.
What else do we have here?
We've got Calculation Settings.
Calculation Settings, what does that mean?
It means it's going to, the angle that's going to study is under 50 degrees,
75 degrees either way.
It's not going to try every single option.
It's not going to try to go towards Iceland to get
to the Southern Ocean, right?
How much time in between the isochrones?
Now the isochrones, I'm going to explain separately.
But for the moment, I'm going to put this on 3 hours and 90 minutes.
Maximum Duration, I don't care.
I'll go as far as the weather will take me.
I've got a polar here.
This is about the GRIBs.
Right, this is the file we loaded before.
We saw that this file was actually a ten meters height,
that's very standard for meteorological stuff, ten meters height.
But on a IMOCA 60, as in the Barcelona World Race where the masts are at 28
meters or something, it is blowing harder on the top of the mast than at the bottom.
It's blowing harder on your roof than on your bike,
so I'm going to move that a little bit.
I'm going to put it at 112%.
So 12% more is about good, which means instead of 20 knots,
it'll probably blow at 22, 23 knots on your masthead unit all the way on top.
Right, not the same as on deck.
Few more parameters here, we want to use a GRIB file,
I'm not sure what you want to do with the constant wind but
we want to use GRIB file because we have one right?
Here are some settings to take you out of the really calm stuff.
And this is some settings to take you out of the really hard stuff.
So I've put in maximum wind 30 knots,
just because 30 knots is probably getting very slow after that upwind.
Downwind, you don't really care, it's just quicker.
Anything else here, current waves,
that's a whole other story which we will not get into at the moment.
Dangers to avoid.
Want to avoid the coast, that's always a good plan.
And you can input in some areas you want to avoid if you know that it is for
instance an ice area or forbidden area by the Race Committee to go into, or
traffic separation scheme.
Know where all the cargo ships go, you're not allowed in there either.
Miscellaneous Options, it's all pretty good, I'm pretty happy with this.
There's a million settings in any program like this,
you can do a lot of complicated stuff with this, you don't need them all.
There we go, calculate and now watch this.
Okay, so here's our route, and here we see those famous isochrones.
Here's the time running, This is where we can get,
I'm just going to stop this for awhile.
If I were to zoom in here on these isochrones, which I do now,
you can see the shape they have.
An isochrone, it's basically based on this polar diagram.
It's a line that joins all the points where we can get for a given time.
In this case, the three hours I put in, 180 minutes.
If I leave from here, I go three hours in any given direction.
Based on the wind direction I have, I can get there, I can get there,
I can get there.
Join all those points together, and I have an isochrone.
Then at that isochrone, I start again with the weather forecast.
And three hours from now,
I can be on anywhere on that line, then I will start on any point of that line and
do the same thing again with the forecast for any three hours.
Then here, I've got a line that joins all these things together, all right?
Let's keep it going.
I'll zoom out.
Zoom out a bit here.
You can see that this one is looking pretty good for right now, right?
Except that here, it's getting really light.
This seems quite close to where we want it to go.
Resume this and keep on going.
You can see that the isochrones get very close together.
You can't get very far in three hours because there is no wind.
The further the isochrones are apart, the more wind there is, the quicker you go.
[SOUND] There we go.
We can't get all the way to the Southern Ocean because we're at the end
of the GRIB.
Any GRIB file has a duration because it's a forecast.
And the longer the forecast is, the more unreliable it gets.
Do you want the forecast for all the way around the world?
It's not going to happen that way.
Right, so do you work with a forecast for four to five days or maybe only for
24 hours, or do you work with the forecast for the week, or ten days?
Those are big decisions the navigator has to make.
But that's what he's going to try.
He's going to try to do weather routing for three days, five days,
seven days, nine days, and then has to look how different the routes become.
And try to find something which doesn't cost that much in the immediate future,
but it's creating opportunities and
will hopefully get him in the right place for the distant future.
