Projected weather/course app

[CassidyNZ]

Originally Posted by belizesailor

True, relying only on models (or just one as many do) without experienced interpretation is a good way to get your butt kicked.

Like the Bowditch adage about navigation...a good weather router never uses just one source of information.

The one voyage that I did in which I used “sources of information” I got information from a renowned weather person in California for forecasting from the US westwards across the Pacific. When I got to Rarotonga I included forecasting from a well-known weather guru in New Zealand. The forecasting received from both led me directly into the only (life threatening) major storm I have experienced at sea.

Before and after that voyage I did my own routing/forecasting and managed several intercontinental passages in total safety. My last 1100nm crossing was done in 7 days without tacking even once (port tack from Fiji all the way to Russell in the Bay of Islands) with only the odd line squall to contend with.

So forgive my scepticism.

There comes a point in a sailor’s life where personal experience and attention to detail trump the information provided by experts who have no exposure to the consequences of getting it wrong. “Good weather routers” are generally not on board when their forecast turns up woefully inaccurate.

Users of PredictWind will know that the software proposes routing based on four different models. They mostly differ from one another sometimes by very significant margins. Most users will have long since realised that one of those models mostly conforms to their thinking and that is the one they consistently reference. On the odd occasion where all the models tell the same story, confidence in the forecasting shoots up but don’t hold your breath for that eventuality.

Multiple models simply confuse me. But then, maybe I’m just not clever enough to tell the good model from the poor one.

[belizesailor]

Originally Posted by CassidyNZ

The one voyage that I did in which I used “sources of information” I got information from a renowned weather person in California for forecasting from the US westwards across the Pacific. When I got to Rarotonga I included forecasting from a well-known weather guru in New Zealand. The forecasting received from both led me directly into the only (life threatening) major storm I have experienced at sea.



Before and after that voyage I did my own routing/forecasting and managed several intercontinental passages in total safety. My last 1100nm crossing was done in 7 days without tacking even once (port tack from Fiji all the way to Russell in the Bay of Islands) with only the odd line squall to contend with.



So forgive my scepticism.



There comes a point in a sailor’s life where personal experience and attention to detail trump the information provided by experts who have no exposure to the consequences of getting it wrong. “Good weather routers” are generally not on board when their forecast turns up woefully inaccurate.



Users of PredictWind will know that the software proposes routing based on four different models. They mostly differ from one another sometimes by very significant margins. Most users will have long since realised that one of those models mostly conforms to their thinking and that is the one they consistently reference. On the odd occasion where all the models tell the same story, confidence in the forecasting shoots up but don’t hold your breath for that eventuality.



Multiple models simply confuse me. But then, maybe I’m just not clever enough to tell the good model from the poor one.

Appears you misunderstood my statement . By "good weather router" in the original context I was refering to the person aboard responsible for weather routing.

A pro weather router is but one "source of information". Relying on a pro weater router exclusively is not prudent.

[largojimbo2003]

Great information one and all. Thank you. You are the reason this website/forum is a "go to".

[belizesailor]

Originally Posted by belizesailor

True, relying only on models (or just one as many do) without experienced interpretation is a good way to get your butt kicked.

Like the Bowditch adage about navigation...a good weather router never uses just one source of information.

Example: I crewed on an Atlantic crossing earlier this year. I was responsible for weather routing. I used all sources I had access to (multiple models, NOAA forecast charts, etc) plus engaged Chris Parker's services. I did my homework each day and then discussed via SSB with Chris. I used every reasonable resource at my disposal to ensure we achieved our goal of a safe, comfortable, uneventful crossing, not a record, we were highly successful.

Seems I should clarify this post a bit.

The Bowditch adage I was referencing was:

“Prudent mariners use all means available to determine their position.”

I think the same philosophy should apply to a cruiser making weather routing decisions...all means available should be used to make those weather routing decisions.

As shown in my example above, a pro weather router is but one of those means (sources of information).

[Paul L]

Originally Posted by belizesailor

Seems I should clarify this post a bit.

The Bowditch adage I was referencing was:

“Prudent mariners use all means available to determine their position.”

I think the same philosophy should apply to a cruiser making weather routing decisions...all means available should be used to make those weather routing decisions.

As shown in my example above, a pro weather router is but one of those means (sources of information).

In theory this sounds like good advice, in practice I don't think so. The example above of using the 4 Predictwind models. Two of them are made up marketing BS. The other two are not PW, just the standard US GFS model and the Euro model available from multiple sources.

Prior to leaving on a passage I look at both models. Tight agreement gives me confidence, sure. If I see something potentially dangerous on a model then I will stay put till the models at least align with each other.
Once offshore, one model is just fine. You have limited actions you can actually do and you have the responsibility to run the boat. Downloading a half a dozen conflicting medium range predictions isn't going to help. It's a cruising passage, not a full crewed race.

I've seen cruisers go into terrible (in)decision mode after receiving 3 different landbased routers advice while half way through a passage. Resulting in what I considered a poor route that added many more miles and burning through fuel that could have been needed at the end.

Too much estimated info, too much repeated and repackaged info, doesn't improve decision making.

[barnakiel]

Scepticism towards your wx router is the healthiest thing you have. Stick with it.


Because your onshore human wx best friend is just like a wx forecasting App - limited by their sources, their algorithms and their skills.


If someone doubts my words, there is a long and entertaining read on the net about the cases when whole Met Offices went wrong and in a big way so - imagine 100 university trained people with 100 very fast machines connected to near real time satellite harvest. So much for teamwork ;-)


And this is from a wx router too. One trained in meteorology and who rounded the globe under sail (with only minor bad wx mishaps - like having the boat upside down).


However, to have access to a human wx router AND an App with RT data AND (!!!) onboard understanding of the weather and basic forecasting beats sailing out without looking at wx forecast hands down, any day of the year.


This is to say: chose your wx awareness methods (human routers, radiofax, gribs, forecasting Apps, etc) wisely and according to the sailing job at hand and do learn basic meteorology and do look out the window.


Bonus point for those of you who have read my blah this far: Believe me or not, working for high altitude climbing teams is actually an even more nerve racking and gray hair generating 'hobby'!


Sail safe!
b.

[belizesailor]

Originally Posted by Paul L

In theory this sounds like good advice, in practice I don't think so. The example above of using the 4 Predictwind models. Two of them are made up marketing BS. The other two are not PW, just the standard US GFS model and the Euro model available from multiple sources.

Prior to leaving on a passage I look at both models. Tight agreement gives me confidence, sure. If I see something potentially dangerous on a model then I will stay put till the models at least align with each other.
Once offshore, one model is just fine. You have limited actions you can actually do and you have the responsibility to run the boat. Downloading a half a dozen conflicting medium range predictions isn't going to help. It's a cruising passage, not a full crewed race.

I've seen cruisers go into terrible (in)decision mode after receiving 3 different landbased routers advice while half way through a passage. Resulting in what I considered a poor route that added many more miles and burning through fuel that could have been needed at the end.

Too much estimated info, too much repeated and repackaged info, doesn't improve decision making.

As I stated "I think the same philosophy should apply...", we dont have to agree.

It also comes down to what method works for you.

[Paul L]

Originally Posted by belizesailor

As I stated "I think the same philosophy should apply...", we dont have to agree.

It also comes down to what method works for you.

With your level of experience I bet that after getting your large set of info downloaded while on passage you pretty quickly discard what is not relevant and then work out what, if any, course changes you'll make for the day. Someone with less experience can easily slip into analyse paralysis when dealing with large amonts of somewhat disagreeing predictions of the future. And even when they pick a course, the nagging insecurity doesn't help make for an enjoyable passage.

[unbusted67]

Originally Posted by Paul L

With your level of experience I bet that after getting your large set of info downloaded while on passage you pretty quickly discard what is not relevant and then work out what, if any, course changes you'll make for the day. Someone with less experience can easily slip into analyse paralysis when dealing with large amonts of somewhat disagreeing predictions of the future. And even when they pick a course, the nagging insecurity doesn't help make for an enjoyable passage.

This sounds like me in a nutshell lol.

[belizesailor]

Originally Posted by Paul L

With your level of experience I bet that after getting your large set of info downloaded while on passage you pretty quickly discard what is not relevant and then work out what, if any, course changes you'll make for the day. Someone with less experience can easily slip into analyse paralysis when dealing with large amonts of somewhat disagreeing predictions of the future. And even when they pick a course, the nagging insecurity doesn't help make for an enjoyable passage.

I agree it could lead to information overload if you dont know what to do with it. Individual cruisers have to sort out what works for them.

Even with experience, a batch of conflicting forecasts doesn't help your pucker factor! Especially if ugly weather is involved.

[barnakiel]

In urban lore, two (somewhat conflicting) forecasts are worse than one. In the computational reality of probabilistics they are not.


The reason being that decisions are done by an actor with additional information. Hence it is a win-win for the sailor.


Unless you want to talk about the situation with a hindsight, and insist on 'I told you so!'


I told you so (hindsight) is not a valid way to judge our decision making methods / skills / preferences. It is not. Because we cannot rewind and repeat wx situations and courses sailed. You only live once (in a boat).


The only parallel that comes to me on the spot is with stock exchange fluctuations and our attempts at beating the market. I believe someone has already proven this can't be done. And markets are way less complex than weather.



There are other factors involved, like e.g. averaging. Humans tend to average, more data is a minor challenge to our brains. We are not talking hundreds of forecasts but say 2 or 3.



Think of that man digging in his garden with a spade. Sure he can place the spade over his other and chop it off. But, tell me, why should one do so? You can elect to be 'baffled' or 'overflown' with wx information but this has more to do with your choices or your personality (e.g how your nervous system handles stress) than with actual difficulty of looking at two forests, THEN LOOKING OUT THAT WINDOW, and then making a decision. Your own. The router is NOT sailing the client's boat. The client is, or their appointed skipper.



More is not worse, it only asks for different (better?) data analysis and decision making skills.


If you are a real poor decision maker, use only one source. But if you are a real poor decision maker, perhaps you should not be on the water.



b.

[Paul L]

You aren't including the cost of getting the additional data offshore. In tough conditions it can take a long and tedious time to download all of the available info. For me, I feel like it is more important to quickly ( at relative term) get a decent Grib and make your decisions. And perhaps put my effort into making sure you the crew has a good hot meal for the upcoming episode.

I download what is effective and easy offshore and so far haven't had the need to try and fill in with more predictions, etc. I do often listen to HF nets to get actual conditions ahead of us that other passagemakers are seeing. This also comes with cost as some Nets can drone on for a long time and be hard to hear.

[CassidyNZ]

Originally Posted by Paul L

You aren't including the cost of getting the additional data offshore. In tough conditions it can take a long and tedious time to download all of the available info. For me, I feel like it is more important to quickly ( at relative term) get a decent Grib and make your decisions. And perhaps put my effort into making sure you the crew has a good hot meal for the upcoming episode.

I download what is effective and easy offshore and so far haven't had the need to try and fill in with more predictions, etc. I do often listen to HF nets to get actual conditions ahead of us that other passagemakers are seeing. This also comes with cost as some Nets can drone on for a long time and be hard to hear.

I download one PredictWind forecast each day on a passage. I take screen shots of the first 3 days of each prediction. I then compare yesterday’s prediction of tomorrow’s weather with today’s prediction of tomorrow’s weather. Soon enough trends become evident and decisions become easier.

But reality is that once you’re out there, it is what it is. Weather prediction is only really helpful to plan departure - once under way, it only helps to diminish the surprises. But if your departure planning is up to snuff, surprises are in any case diminished.

[Paul L]

Originally Posted by CassidyNZ

I download one PredictWind forecast each day on a passage. I take screen shots of the first 3 days of each prediction. I then compare yesterday’s prediction of tomorrow’s weather with today’s prediction of tomorrow’s weather. Soon enough trends become evident and decisions become easier.

But reality is that once you’re out there, it is what it is. Weather prediction is only really helpful to plan departure - once under way, it only helps to diminish the surprises. But if your departure planning is up to snuff, surprises are in any case diminished.

So you download a single Grib model. Which one?

[CassidyNZ]

Originally Posted by Paul L

So you download a single Grib model. Which one?

No, when I say I do one download a day, I mean I don’t do it twice, not that I only do one model.

Depends where I am too. If I’m ashore and prepping to depart, I download on standard PredictWind and I use PWG and PWE. On a passage I use PredictWind Offshore, I download the same models.

However, I use PWG as the primary and PWE as a comparison. If PWE differs widely, PWG is my sole reference. Interestingly, the forecast in my area for the next 10 days shows both models as nearly identical, would give a high level of confidence.