He Does Weather Routing, Not Miracles

Winter North Atlantic, not a good place for yachts.

I have been using weather routing companies for over 25 years, anytime I have had to make a tricky passage, particularly early or late in the season.

(Less so in recent years when improved models and less expensive satellite data have allowed me to develop and perfect my own routing procedures—see the blue box below the video.)

That said, I’m seeing a recent trend of some sailors assuming that a router is a miracle worker who can make any passage safe and even comfortable.

But, as I related in a recent article, that’s not necessarily so, particularly when making a North Atlantic passage in November with winter coming on fast.

Worse still, voyagers are now regularly setting off on multi-day passages even in mid-winter. A trend that tells me they have completely missed the fact that a model that is consistently accurate out to five days in settled summer weather can be badly wrong just two days out from forecast time in less settled seasons.

But don’t take my word for it. Rather, let me hand you over to Ken Campbell, founder and senior router at Commander’s Weather. I know it’s 45 minutes long and you are busy, but this is really worth your time. Ken is the real deal, and he is showing big-time integrity in sharing the limitations in what he does and the data he (and we) use.

After you get done watching Ken, scroll down for some thoughts on how to learn about weather.

Learning About Weather

There are eight additional segments by other presenters (all of whom I admire) available from the same one day seminar.

Sounds like a great way to learn about weather, but, having watched all but one of the presentations, I found that the others suffered from the standard problem of one, or even two, day weather seminars: trying to cram too much in.

This results in attendees getting deluged with theory, that, if they are anything like me, will stay between their ears for a good five minutes, but coming away with little hard actionable information.

I mean seriously, Lee Chesneau, one of my weather heroes, would need most of two days to lay the ground work before he could teach us stuff we can use offshore, not 45 minutes.

I think most people who wish to get a basic grounding in weather for self-routing offshore would be better off to:

  1. Read Frank Singleton‘s Weather Handbook. It will only take you a couple of hours, at least for a first pass. I have never seen a better way to wrap your arms around the basic theory in the minimum possible time. (Get the paper version, graphics suck on Kindle.)
  2. Read our Weather Reception and Analysis Online Book, for a step-by-step how-to—another two hours or so.
  3. If you really want to get into it, move on to the “Damned Book“.

All that said, I did learn some useful stuff from most of the videos, so here are links to the others so you can judge for yourself:

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Meet the Author


John was born and brought up in Bermuda and started sailing as a child, racing locally and offshore before turning to cruising. He has sailed over 100,000 miles, most of it on his McCurdy & Rhodes 56, Morgan's Cloud, including eight ocean races to Bermuda, culminating in winning his class twice in the Newport Bermuda Race. He has skippered a series of voyages in the North Atlantic, the majority of which have been to the high latitudes. John has been helping others go voyaging by sharing his experience for twenty years, first in yachting magazines and, for the last 12 years, as co-editor/publisher of AAC.

21 comments… add one
  • Marc Dacey Dec 27, 2018, 1:23 pm

    Very good, John…and yes, “the damned book” is beside the bed…I can manage three pages or so of Hadley cell talk before I fade. The Singleton one is a doddle after that. I would be curious to learn what discovery or conclusion switched you from buying your routing to having confidence in your own abilities, because in either case, the point is to avoid directly whether the drogue works as advertised. Although in some cases, you want to use the edge of a decently large wind field to have 48 hours of fast passagemaking before the wave train gets unruly, and certainly ocean racers try to skate that line.
    As an aside, I wonder if Les Chesneau is recovering. I’ve attended two of his seminars, and you’re right, even though he is a great explainer of deep concepts, even two hours is not enough to appreciate the conceptualizations he grasps.

    • John Dec 28, 2018, 10:11 am

      Hi Marc,

      I have always taken a deep interest in the weather and done most of my own routing and departure decisions so there was no sharp transition from using a router to rolling my own, but rather a slow move to doing it myself more and more as I became more confident. That said, if faced with a really tricky passage like a fall trip to Bermuda I would still consult a router for a second opinion.

      • Marc Dacey Jan 1, 2019, 1:32 pm

        My skipper on a November delivery past Bermuda concurred and we were able to have the famous Herb H. route us daily between two systems full of rough stuff. Some places, I agree, are too complex and capable of rapid evolution to easily predict below the non-professional level. A similar place would be the southern end of Africa, I suspect.

  • GARRY CROTHERS Jan 1, 2019, 8:35 am

    Great videos, but it’s a pity there is no access to the slides. Especially the 500mb video by Les. Still way above my head.


    • John Jan 1, 2019, 12:45 pm

      Hi Garry,

      Yes a slide stack would be nice. That said, I think the only really practical way to get our arms around the 500 mb and how to use it is Lee’s book.

  • PaddyB Jan 1, 2019, 10:22 am

    As ever thanks for article & links, such an interesting and important part of cruising. One problem I keep hitting is how can you quantify the accuracy of any forecast from observations? Done it before for a week or 2 just with a spreadsheet entering GFS forecast wind/gust & actuals from a local airport, the GFS did very well 🙂 But a load of work and not really practical. Anyway, the GEFS model seems interesting by seeing when the model starts to go a bit crazy with tiny differences in initial conditions – so is this a good indicator for reliability? This site has GEFS-SPEG and 500mB –
    .. and here does similar but with other options like surface wind –

    Then back to where we started – how do we know it helps? I’m guessing that a close spread of GEFS plots will suggest the model likely reliable up until the spread starts to go haywire. But could be wrong…. If anything then looking at the GEFS might at least make it more obvious to our modern ‘digital so must be right’ bias staring at one model run output and take onboard that they are all just most likely outputs from some extremely powerful computers.

    • John Jan 1, 2019, 12:47 pm

      Hi Paddy,

      Yes, accessing model accuracy is difficult. And, as you say, vital. Here’s a suggestion from a professional: https://www.morganscloud.com/2016/03/04/4-great-tips-from-a-professional-meteorologist/

      • Ernest Jan 1, 2019, 2:06 pm

        Yup, I remember last September when we were in the middle of the med, wondering why the weather did not obey to the grib model predictions 😉
        But then, in the med there is so much of land mass influence that a big weather pattern such as in the atlantic cannot be expected, except effects such as Meltemi or Mistral (which again are effected by weather on the mainland) which is a completely different topic.

      • craig burnside Jan 2, 2019, 6:40 am

        It’s a double edged sword, assessing weather models IMHO. First figure out a way to get a handle on the accuracy then figure out a way to assess the accuracy of your accuracy assessment 🙂 Neither easy – maybe you just got lucky!
        I’m drawn towards the more probabilistic approach from the GEFS model ensemble et al , like the Probabilistic Wind Speed Guidance from OPC instead of a one off best‐guess deterministic forecast with no data on certainty. Or rather both, like nav – anything and everything.
        Interesting piece here > https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017MS000999
        Pinching from that piece – maybe an idea for something to write about – ” embrace the concept of primacy of doubt”! Not just in weather, but in all things sailing, you can only control or predict the future in degrees of certainty, remembering this may help you focus a little better. Maybe 🙂

        • John Jan 3, 2019, 12:17 pm

          Hi Craig,

          Yes, I agree that there’s a lot to like about the Probabilistic Wind Speed Guidance: https://www.morganscloud.com/2018/01/29/great-new-weather-forecast-product/

          I have also already written a lot about the importance of understanding “the primacy of doubt”. Here’s just one example https://www.morganscloud.com/2011/09/29/lessons-in-hurricane-forecasting/

          That said, I agree, always a drum worth pounding.

          • PaddyB Jan 7, 2019, 6:59 am

            After some playing around in python, this might be of interest >
            Just a rough playaround but seems to work, the data is actual wind and forecast data for Scilly St Marys from UK Met Office. Click on the legends to turn on/off plots. This was chosen as it’s a low island. So far pretty accurate even 5 days out, which sort of talleys up with the GEFS. Plotting data is essential IMHO, not much chance of seeing the trends just string at a bunch of numbers. And every boat should have a Raspberry Pi to do all this fun stuff on 🙂

          • John Jan 7, 2019, 11:21 am

            Hi Paddy,

            Wow, that’s interesting, and comforting to.

  • PaddyB Jan 2, 2019, 6:52 am

    It’s a double edged sword, assessing weather models IMHO. First figure out a way to get a handle on the accuracy then figure out a way to assess the accuracy of your accuracy assessment 🙂 Neither easy – maybe you just got lucky!
    I’m drawn towards the more probabilistic approach from the GEFS model ensemble et al , like the Probabilistic Wind Speed Guidance from OPC instead of a one off best‐guess deterministic forecast with no data on certainty. Or rather both, like nav – anything and everything.
    Interesting piece here > https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017MS000999
    Pinching from that piece – maybe an idea for something to write about – ” embrace the concept of primacy of doubt”! Not just in weather, but in all things sailing, you can only control or predict the future in degrees of certainty, remembering this may help you focus a little better. Maybe 🙂

    EDIT – Sorry John, double posted after trying the back button to fix putting in the wrong name.

  • Philippe Candelier Feb 19, 2019, 11:48 am

    We should remember that 95% of the sailing community is weekenders and coastal cruisers. The largest offshore passage they will do is a gulf stream crossing from Florida to Bimini. And they will be extra careful in the weather window selection.

    I know 2 influencer persons here in the Montreal community that teach weather for cruisers and sailors that do not believe in the vertu of the 500mb. What ever you told them, what ever you do to try to convince them, they still think it does not bring anything more than what you already get by looking at GRIB files. Because they market themselves to that 95% of the crowd they do not feel the need for the extra hassle.

    It is rare opportunity to access weather seminars of that level, and not everybody is interested in this. There is a bias here at AAC because of the serious off shore sailing community.

    • John Feb 19, 2019, 12:57 pm

      Hi Phliippe,

      Yup, that’s what we do: offshore sailing.

      That said, I make clear in our weather book that study of the upper level is definitely optional: https://www.morganscloud.com/series/weather-to-go/

    • Dick Stevenson Feb 19, 2019, 5:26 pm

      Hi Philippe,
      I just wish to make a comment on a side issue: I know what you mean by your distinction of “serious off shore sailing community”: that distinction is made periodically on this site (and often in the cruising community in aggregate). I would want to suggest, in a general way, that the distinction may not readily apply to sailing. Of course, there are gradations in the level of experience/skills/preparedness, but emphasizing these distinctions could (and does, to my mind) obscure the fact that, once one leaves the mooring/slip, your outing can become unexpectedly quite challenging very quickly. Sailing, to my observation and experience, has the unique distinction of being quite unpleasantly surprising whenever you are on the water.
      This is unlike most activities. Someone strolling in a local park need not be as prepared/skilled/experienced as a back-country hiker: the conditions the park stroller finds are generally quite predictable. And situations do not become pear shaped quite so quickly nor are the down sides quite so potentially serious. The back-country hiker needs to be well prepared, the park stroller might wish to carry an umbrella. I would contend: not so with sailing: conditions for sailors are often quite predictable, but when they are not, the potential for serious consequences is high. And most of us are not “conditioned” if you will, to recognize the dangers: to anticipate where things might go pear shaped the way we are “conditioned” to recognize without really thinking land based dangers and challenges.
      I say this as, it is my take, that coastal cruisers, weekenders, even day sailors, can experience adverse conditions that would task the talents of any sailor, offshore experienced or otherwise. I suspect the majority of topics discussed on the AAC site pertain just (or nearly) as potently for all who take a sailboat off its mooring, not just to off-shore sailors. I worry that the distinctions made might lead sailors who are not “off-shore” oriented to downplay the preparation necessary to take their boat, themselves and their loved ones out cruising.
      One example and one comment may suffice: it used to make me cringe (still does) when I see parents with babies carrying them around in what I called a “snuggly” (chest holder of some sort) and they are doing stuff around the water and boats. They reason, accurately, that they have control of their infant and that they have two hands to operate with: sometime to operate the boat or dinghy or to get off a launch to shore. The ones I occasionally spoke with did not realize that if they happened to fall in the water, they might keep their head above water, but their infant might easily die given the amount of time it would take to extricate them from the snuggly.
      The comment I refer to came to me from an acquaintance who had just returned from a very boisterous race to Bermuda. I was carrying on about how scared I would have been and probably dis-functional in an impressive variety of ways. He responded that what he did was no big deal: work a little, follow instructions and hang on tight and that he thought my wife and I needed far more skill and were far the braver to take ourselves and our 3 children coastal cruising.
      I am not sure what to do about this: everyone has to start somewhere. But I do believe that when a skipper takes to the water, especially with family, he/she should not be thinking “this is a walk in the park”. And I worry that distinctions such as “offshore” sailor may contribute to the thinking of the less overtly adventurous sailors that they can be less diligent.
      I feel like the above could be better said, but I suspect my drift is apparent.
      My best, Dick Stevenson, s/v Alchemy

      • John Feb 20, 2019, 10:34 am

        Hi Dick,

        Now that’s a really good point that I had not thought of in that way, but I will now. I’m also thinking we should take it into account in how we market AAC. Thanks very much.

        An aside, we are currently in the Canadian Rockies and doing quite a bit of Nordic skiing, most of in easy places on groomed tracks. But even so it scares the hell out of me to see people 5-10 kilometres from help or warming in -15 to -20C temperatures but lightly dresses and with no pack indicating that they don’t have any spare clothing. As a very experienced in the mountains friend said “there is no such thing as a day hike”. Ditto day ski or day sail.

        • Dick Stevenson Feb 20, 2019, 11:10 am

          Hi John,
          Similarly, in high country day hiking, we see folks in a t-shirt and shorts on a nice day 5-6 miles from the trailhead who, to my view, seem to have no clue how rapidly conditions can change if the clouds roll in, the wind picks up a bit, perhaps a little cloud/fog or drizzle. Most could easily jog/hike fast to return quickly, but add in a twisted ankle and life could get serious pretty quickly.
          A few weeks ago, I was “lost” on a very obscure trail about 4 miles or so from the trailhead with less than 3 hours of daylight left: pretty close to (actually exceeding a bit) my personal safety limits hiking alone. I know I am pushing it when I start spontaneously reviewing what is in my packed kit: water, power bars, matches etc. and what a night out would be like: then I appreciate the extra couple of pounds I carry on most outings.
          Sailing is certainly in the ball park of outings like high country hiking and Nordic skiing, but it does, to me, seem qualitatively different in many respects: not least of which is the complex machine, the boat, that must be safely managed.
          My best, Dick Stevenson, s/v Alchemy

      • Rob Gill Feb 20, 2019, 4:07 pm

        Good point Dick,
        Doesn’t this apply doubly (squared?) for smaller yachts? What could be a straight-forward passage in Morgan’s Cloud might be lively in a 40 footer, challenging in a 30 footer, damned adventurous in a 20 footer and brutal and / or dangerous in the 15 foot open day boat I learned to passage make in. As Peter Blake said, “if you haven’t been sea sick, you haven’t been in a small enough boat in a big enough sea”.


  • Wilson Mar 4, 2019, 9:40 pm

    A very experienced sailor, CCA member and all that, once said to me that she thought inshore sailing is often a more serious test of boat and skills than offshore work is. Having done a fair bit of both, I agree. Although quick to admit that I have not been tested to the limits, I’d say that barring major gear failure or disaster like person overboard, going offshore is mostly an endurance contest for crew and gear with rare moments of real concern and, when they occur, lots of room to recover from mistakes. Coastal sailing has most of the same risk of gear failure or person overboard with the added constraint of proximity to rocks and traffic. Along shore passages should be approached with the same respect as off shore ones. Both demand preparedness and caution in terms of weather, gear and crew. I can say from experience that single handed coastal passages are very demanding, and doing them at night is best described as foolhardy. Give me sea room any time!

    • John Mar 6, 2019, 9:01 am

      Hi Wilson,

      I totally agree. I have to admit to having done a few single handed night coastal passages some years ago, but I certainly don’t recommend it and can’t claim that so doing was seamanlike.

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