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Gribs one or two times a day, Cruising.


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Gribs are probably one of the best tools out there that we have, why not use them?  I'd rather spend more time sailing and yes like all tools use them in conjunction with your own analysis and knowledge of the area.  

 

At the end of the day spend the time ensuring your vessel can handle the weather that may occur rather than spending time reinventing the wheel. 

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No forecast is 100% accurate. I've found gribs very useful, and compare the different models. If they all agree, then they are usually more reliable. But it is still only one factor in my decision making.

That being said, if you or your boat can't handle a gale at sea, don't go.

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Gribs are probably one of the best tools out there that we have, why not use them?  I'd rather spend more time sailing and yes like all tools use them in conjunction with your own analysis and knowledge of the area.  

 

At the end of the day spend the time ensuring your vessel can handle the weather that may occur rather than spending time reinventing the wheel. 

 

 

I am not a weekend sailor.  I live aboard my ship and will sail the entire world many times over.  And in doing so, I, not NOAA, not the NHC, not anyone else, will make weather predictions.

 

For you, GRIBS are probably just fine, most of the time (I really love how everyone just glosses over the fact that this thread admits that GRIBS are only accurate "most of the time.")  But if you rely on GRIBs, you are gambling, and "most of the time" you will be okay.

 

But in the world I live, most of the time isn't okay because of what happens in those other times.  Most of the times that the GRIBS say the wind won't be dangerous, it will be right.  But what about the time the GRIBS are wrong?  Without disciplining yourself to predict the weather, to confirm what the GRIBS say, you will become dependent upon them.  And that one time that the GRIBS say 30knots and you end up in 70knots of wind, may well be your last time, ever.

 

I don't want to sail safely and soundly "most of the time."   I want to sail safely and soundly ALL THE TIME.  And for that, I will rely on my skills and observations.

 

 

 

Oh, and I have neglected to incorporate one VERY important element in my reasoning for not using GRIBS:  Global Climate Change.

 

 

You see, GRIBS are based on climate modeling software.  Supercomputers and even regular computers churn out models all the time, and they are meant to accurately predict weather conditions based on observations and trends.

 

For example, did you know what a percent chance of rain means?  It means that under the observed conditions, it rains that percentage of the time.  Meaning, the models used to predict weather conditions are based in large part on past weather and the corresponding observations.

 

But these observations are not complete.  If they were, they would be flawlessly accurate.  And in my study and observations of weather, I have seen a disturbing trend: that the models are no longer valid in any reliable sense.  And this observations correlates very strongly to my observations of global warming and the predictions: which are grossly flawed because they fail to consider all factors, most especially the result of the models, of the warming itself.  As a result they show a linear, rather than geometric progression (and which is why I am anxious to get to the Southern Hemisphere.)

 

So we have a situation where inaccurate models are being relied upon even as they grow more inaccurate.  So, the "most of the time" that GRIBS are accurate is becoming less and less often.  And that doesn't sit well with me in the least.

 

 

For those interested in learning how to predict weather, I suggest starting with Donn's Meteorology and go from there.

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Disperser, never said I rely entirely on GRIB's only that they are a useful tool, one of many.  I think there is a huge focus on technology on board boats these days over skills and experience, but I think back to my first offshore trip I did when I was 18 and had zero skills really.  I still survived, had no SSB, no 406 EPIRB, a VHF handheld and some freeze dried food and water.  I had no idea what I was doing rather relied on learning off other sailers around me, reading about weather and using the good old 101 eye.  

 

Saying that would I do that today?  No way, if technology is available why no harness and use it?  Of course have a backup which is prudent seamanship.  I've seen overstudy of weather happen time and time again where groups of 'sailers' huddle into circles and study weather until they have given themselves good reason not to leave port then go back to their G&T and wait for another weather window.  

 

Often that energy in my humble opinion would be better spent preparing yourself and the boat to tackle whatever is thrown at you and the boat.  After all most of the battle offshore is your own mental state and ability to handle problems correctly as they come to hand.  

 

Case in point a well prepared yacht will probably handle most weather problems anyhow, it's the people that typically give up first.  Obviously your opinion is strong on this subject, I on the other hand choose to believe that if a tool is going to make an experience better why not use it?  

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Disperser, be careful about thinking everyone on this site is a "weekend sailor". Many here have much time at sea, and many miles, and have been/are live aboard sailors. Think about this - there are over 10,000 cruising boats out there, away from their home countries. 

 

Weather is a chaotic system. No-one understands it fully, or can give 100% accurate forecasts, it's just too complex. Like Southernman says, Gribs are a useful tool, but not the only source of data of course. What the weather is doing in your location, does it sync with the forecasts, whats the wind doing, clouds, barometer, etc etc are all things any competent offshore sailor understands. The further from main civilisation you are, and away from the shipping routes, forecasts tend to be less accurate.

 

If your forecasts are 100% accurate, and outdo the primary weather models run on supercomputers, you should be able to sell your versions and make a good living I would think.

 

People do make a living at this - Predictwind.com is an example.

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Gribs are famous for missing the ridges and troughs, but no one  relies on just one source.

An isobaric forecast is basically just the same as gribs but without the numbers( and showing the ridges and troughs ). Still a forecast , still a 'model'.

I always look at the situation first. Passage making is not about micro managing the weather between  5 and 35 knots , its about watching the trend and whether a cyclone or deep depression is forming up and whether its coming for you.

 

 Who remembers Drena and Fergus in the '90's?  How things have changed , those bastards were coming down on us right at christmas when every person with a boat was on the water, Metservice knew and deliberately withheld the information because their mandate of service at the time was to only go out  a certain number of days( 3 IIRC).

The only way we found out about them was it was broadcast on 1ZB and bush telegraph around the boats, there was no mention of either on  21.

 I'll take the isobaric situation map and any number of forecast models,gribs or whatever... make up my own mind thanks.

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I'd like to see if someone could find a study showing the accuracy of GRIBS in any way.  This is simple.  Just a comparison of GRIB data and observations where possible to compare accurately (i.e. GRIB versus nearby physical observatory) how accurately the GRIBS predict conditions.

 

I tried a quick search and found nothing in the way of scientific documentation.  It need not be a scientific study as it's easy to do with software.

 

This is, by the way, an excellent exercise for anyone considering or using GRIBS.  And you should do this yourself.  Manually if you have to.  Just get GRIBS for your area and compare with observations.  Record the values.  Accumulate data, and analyze to show yourself how well GRIBS work and thus how much you should rely on them.

 

 

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Interesting news from Predict Wind today:  http://us6.campaign-archive1.com/?u=d5dbbe0f26fe7f4565891071a&id=ded22931ba&e=889c4810d9

 

It seems that Predict Wind will be even more accurate.  

 

Just had a conversation with a mate delivering a Catana to NZ and due into Opua on Wednesday next week, be interesting weather I think and a fast passage looking at the wind coming.  

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I think anyone that has actually done a few offshore miles is aware that any forecast more than a day or two into the future will be liable to change.  +1 to the idea that your boat should be capable.  -1 to the idea that it is possible to have perfect weather wherever you go, when you want to go.  

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All forecasts are modeled from the  situation and they are continually reset to real. A grib is just a simplified forecast wih arrows instead of isobaric lines. A short time frame( say 6 or 12 hours ) grib forecast is near as dammit the same as a situation plus an allowance for that elapsed time or any other isobaric/ metvuw  metservice type forecast. Its the same data  that has made it as all the other stuff we look at. GFS etc American/ Canadian/ European interpretations whatever.

 

 So why a grib is supposed to be such a terrible thing is beyond me. Its the same, except , as many have said before and I have said here, they don't tend to show  ridges and troughs . And as we know , those ridges and troughs can contain localised extremes, squalls etc and which we all just cope with as a matter of course .

 

 I' haven't felt the need to state what I see as obvious , we've all developed as sailing people through the years looking at metservice situation and forecast maps stapled to our yacht club walls, and then the interwebs came along and put it on our phones.

Of course we make our own assessments of what is likely to happen, and now we get to look at differing models on sites like windyty  and metvuw and metservice and predict wind,and see what a pretty wide group of meteorologists think too.

 Great, bring it on.

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