Mike Heritage FFF MCI UK

Fly casting and talking fly casting bollox


Like most casters I have a few theories. I like theories because most of them can’t be proved, or better yet, disproved. I don’t often go to the trouble and try and justify any of them but now and then, well once, I did decide to try and put one to the test.

All distance casters have had those days when no matter what you do you just can’t get the line to fly. It’s almost as if the line hits an imaginary brick wall and collapses in a heap many feet from where you think it should have gone. It’s a very annoying phenomenon when you know you are casting well. If you are still at the inconsistent stage where you are not sure what the hell is going on it can totally demoralise you. Yesterday you could hit 110ft standing on one leg and whistling Dixie and today you couldn’t hit 100ft if your life depended on it.

Before you hurl the rod on the ground and stomp on it go find out what the barometric pressure is, if it’s above 1025MB blame the weather, if it’s below 1000MB then you are just having an off day so pack up and go home before you give yourself a heart attack.

Another bugger is high humidity, I have literally lost 20′ in half an hour because the dew was starting to fall just before it got dark. I made the mistake once of having a bit of a shootout with some friends after we had cast into the evening, I chose to cast last and by the time it got to my turn the air was so humid it was like casting under water, I got hammered.

To test out my theory about barometric pressure and humidity I decided to keep a record of my distance casting practice so I bought a weather station that gave me not only temperature but humidity and barometric pressure as well, I also got hold of a little anemometer to measure wind speed. I then recorded all of these measurements along with my observations on the weather like sunny or cloudy. Added to this I noted the rod and line I was using and the longest cast and my estimation on the average distance. The average had to be an estimation because I was damned if I was going to walk up the tape and measure every cast.

So, what conclusions did I come to?, none really. My CCI test got in the way and I stopped casting distance for a while but as I look at the chart I can see that my best days were when the BP was under 1020mb and low humidity (below 65%) and my worst days were when when BP was 1038mb, or higher, and high humidity (above 75%). Wind speed on both occasions was in the 2 to 4 mph range.

I do remember one day that was 940mb and I threw just under 130′ several times and another day of 1040mb when I couldn’t hit 100′.

Once I have got myself back into regular distance practice and achieved some sort of consistency I will start to record again.


February 13, 2009 - Posted by | Distance casting, Mike Heritage


  1. hey Mike !

    great stuff. would you attribute these reduced distances to the higher water content level in the air, acting as a barrier to the line (horizontal friction) like when it rains or that barometric pressure ‘pushes’ the line down (vertical friction)?

    i’d guess probably both.


    Comment by marc fauvet | February 19, 2009 | Reply

  2. Ah, well you see Marc I don’t know WHY it happens , I only know it does. I leave the why’s and wherefores to other’s. I do know that altitude makes a huge difference so it stands to reason, in my book, that barometric pressure will also have a big influence. High humidity is a known cast killer.


    Comment by Mike Heritage | February 19, 2009 | Reply

  3. this might be a good one for the ‘engineers’.
    let them do the work while we sit back and dream of loop shapes. 😉


    Comment by marc fauvet | February 19, 2009 | Reply

  4. Nah, ignorance is bliss, they would only confuse me.

    Where did you get the smiley from??


    Comment by Mike Heritage | February 19, 2009 | Reply

  5. 🙂 i know what you mean…

    just punch ; then – then )

    Comment by Marc LaMouche | February 19, 2009 | Reply

  6. Hi Mike,

    I have just discovered this blog. Congratulations.

    Very interesting issue this about humidity and barometric pressure. I don’t know why it happens but you are spot on. Where I live humidity is very high all year long and we are at sea level. I have noticed since long ago that I can cast at least 2 or 3 m longer in central Spain (dry climate and 600 m above sea level).
    It is a good thing if you must take a test at a “high and dry venue”. :^)

    I suppose that the altitude issue is due to the air being less dense the higher you are: less density gives less friction.



    Comment by Aitor | February 24, 2009 | Reply

  7. Hi Aitor, I’ve gone international!.

    Nice to find someone who agrees with me. There is definately something that inhibits the line on occassions, whether it is barometric pressure or humidity that causes the biggest problem is something I would like to understand properly.

    Nice comment, thank you.

    Comment by Mike Heritage | February 24, 2009 | Reply

  8. Hi Mike, nice site.
    I think your theory’s stand up scientifically.
    With a higher air pressure wouldn’t the line weight(in relation to the weight of the air) be lower as the air is denser. This could maybe cause the line to “float” as well as have increased friction and possibly reduce distance and momentum?
    Humid air would have the same effect.
    I’m thinking also the difference in casting a sinking line in relation to a floater.
    I like fly-casting 😉

    Comment by jamie | March 3, 2009 | Reply

  9. Hi Jamie,

    As I have said, I leave the why’s and wherefores to others, I just know it happens. That’s good enough for me.

    Comment by Mike Heritage | March 4, 2009 | Reply

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