Weather routing/information

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CPD

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I think Roger Taylor is right (I hope I am not misquoting here !) - our boats are too small and too slow to be able to outrun or outmanoeuvre any weather system, so just take what comes, and be prepared for anything. (Apologies if wrong Roger !)
 

Gargleblaster

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I'd agree with that. I even find the information you get from ships is misleading because they are looking a lot further ahead than you.
I have just read Ewen Southby-Tailyour's biography of Blondie Hasler. In that he mentions that Blondie even got rid of his barometer as he found that the information it was giving him was not really useful as he couldn't escape the systems. I don't think I would like to get rid of the barometer as I find it very useful to know that it is getting worse or is getting better. Not that it changes my actions or decision time in any way. /forums/images/graemlins/ooo.gif
 

JunkMing

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You quoted me just about spot on, Alan!

I've recently written a couple of articles relating to this that should appear some time soon, either in the yachting press or on my website.

If you are weather routeing, then you are either trying to avoid very high pressure and the lack of wind thereof, or very low pressure and the excess of same. The former is impractical ( as far as Jester style yachts are concerned) because of the size of the systems and therefore the distances to be sailed to get round them. The latter is impractical because of the speed and unpredictability of a developing severe low.

The unpredictability is probably a greater issue than speed. The fact is that even when a severe low has reached the mainland, and the Met Office has as much data on it as it's ever going to get, it consistently mispredicts the track. It's only ever educated guesswork. The further offshore you are the less reliable the already unreliable predictions.

It could be summed up as follows: predictability is always in proportion to pressure and in inverse proportion to distance offshore. In other words weather routeing in relation to heavy weather could just as easily put you in the wrong sector as the right sector. This does not mean, of course, that the normal rules for avoiding the centre of a depression should not be followed once you are in it.

The good news is that once you are out of soundings then any well-found yacht (properly handled, of course!) should be able to ride out all but the most unthinkable conditions.

In less than 200 metres and where there is steep shoaling, current and tidal influences, and, of course, that nasty stuff called 'land', it's a different story. My own approach is not to be too exercised about where I'm going to be in relation to the weather system, but to be seriously concerned about getting myself into the deepest water with the best all-round sea room.

Here are two practical examples from my 2007 voyage to illustrate the above points. I had the pleasure of being off the Yorkshire coast when the devastating storm of 24/25 June came through. It was forecast to pass via Tyne and Dogger. Within five hours the Met Office had changed this to Thames. My weather-routeing dawdling changed rapidly to getting north as fast as I could. This was not to try to avoid the weather, but to get myself into a better position, between Whitby and the Dogger bank, and well clear of the gas rigs and Humber shoals, before the worst hit.

Coming back, off south west Ireland, I collected all the lows that caused the second round of flooding. Although I had a fair wind for carrying on into the Celtic Sea, I kept myself in the deeper waters of the Porcupine Sea Bight - c. 2000 metres - by holding position for two days until the worst had passed. The Celtic Sea is of course a prize example of of water that has all the unsavoury attributes mentioned above. To wilfully and knowingly give up sea room and a pelagic depth and sail on past Fastnet, given the general synopsis, would, in my view, have been seamanship of the worst order.

Like John, I would not like to be without a barometer. It's the only weather instrument I have. It does give you a general feel for what's going on, and of course those rapid falls (and rises) of pressure do put you on alert.

Anyway, to get back to the original question posted - I wouldn't bother with all that stuff!

Roger
 

Saddletramp

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[quote )Anyway, to get back to the original question posted - I wouldn't bother with all that stuff!

Thank gawd for that. Something else I do not have to buy, fix, understand, squeeze in, swear at etc
 

PacketRat

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[ QUOTE ]
This does not mean, of course, that the normal rules for avoiding the centre of a depression should not be followed once you are in it.

[/ QUOTE ]

Nice post. /forums/images/graemlins/smile.gif Would you like to expand on the normal rules? Is that something on the lines of being on starboard tack when approaching a low? /forums/images/graemlins/confused.gif
Cheers,
Robin.
 

eebygum

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Found this of interest off another thread.... you can get a free copy of the North Atlantic Weather Routing information at:

http://pollux.nss.nima.mil/pubs/pubs_j_apc_sections.html?rid=10499

May just help you decide which route you want to take.... but I'm not opening that debate !

BTW, I will be going with SSB (NASA HF3) and weatherfax - but I'm a technical geek who likes his gadgets and listening to the radio !

Cheers, Andrew
 

andlauer

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Bonjour
For once I partially disagree with my friend Roger but it's perhaps because my boat is so much faster than others... /forums/images/graemlins/grin.gif

Nowadays you have useful information, not always true or accurate but useful in the term of supporting strategic planning on a 10 to 15 days basis.

The most important information is the positioning and life of great meteorological phenomena as highs and lows trajectory.

The forecast are better offshore because you don't have the nasty interaction with land. The models are worldwide and satellite or any plane crossing the atlantic provide real time met data.

I've used one days ahead forecast data (wind grib files) for the JC06 mainly to limit the strategic advantage.

I had full routing for the return.
For example, I've sailed three consecutive days to the North East on the return travel to avoid a building up high and it worked.

What was not predicted was the bounce of a tropical low on the Gulfstream-Labratorstream boundary with an increase in the phenomena that provided us with 40kts+ of wind.

I was very happy to have good prevision to be in position to rush (8 to 10kts mean continuous speed on GPS under spinnaker with 25kts of wind) to Morlaix on the 12th and 13rd before the 40kts low that passed on August the 14th on Celtic sea.

With good Gribfiles the barometer is mainly a tool to position yourself in the system.

I agree with Roger that it is much more pleasant to sail alone with no contact with the civilization... But, anyway I have to keep in touch with my family especially the younger ones so... I pull down the gribfiles.
Eric /forums/images/graemlins/smile.gif
 

webcraft

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[ QUOTE ]
our boats are too small and too slow to be able to outrun or outmanoeuvre any weather system

[/ QUOTE ] Maybe but . . . we found weather routing via satphone and GRIB very useful on our longer passages last year, and used it to very successfully to avoid the worst of a couple of lows - once between the Azores and Galicia and once coming back across Biscay. On the first occasion we altered course by 30 degrees for two days and on the second occasion we slowed the boat down for 24 hours, and in each case avoided worse weather.

(Boat is an Albin Vega 27)

Even if you can't avoid or moderate something it is IMO better to know it is coming and to be mentally and physically ready for it.

- W
 
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