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Effect of temp on casting

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Boisker
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Effect of temp on casting

#11

Post by Boisker » Sat Feb 02, 2019 9:41 pm

Paul... I didnt realise that the wind made such a significant contribution.

Where I practice is a bit of a nightmare for wind and and distance casting... especially if you are new to it and trying to extend carry. It’s not the wind as such, casting to 60’ is fine, I like practicing in the wind. But I live in a fairly typical Devon Combe (steep sided valley) that twists and turns up from the sea, the wind can be all over the place... it can constantly move to all points on a compass... switching 45, 80, 180 degrees and back again in seconds... makes concentrating on a long carry challenging.
Saying that it’s really useful for practicing fishing distances

Perhaps that’s where my missing 35’ has gone :D :D :D

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James9118
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Effect of temp on casting

#12

Post by James9118 » Sat Feb 02, 2019 11:31 pm

Paul Arden wrote: In December we had a competition in Malaysia where I cast 118ft. Same month in England I threw 139’. One had no wind and a limp line. The other I had to have someone holding my ankles to stop me getting blown into the lake.
You've got to factor in height above the water in the 139' one also though.
For me with a #5 there's a window of wind speeds where I'll get my best distances, too much and my results fall off. This is not such an issue with heavier outfits obviously.

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Effect of temp on casting

#13

Post by Boisker » Sun Feb 03, 2019 12:08 am

Hey James... what’s the upper end of the wind speed where it starts to have a negative effect?

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Willy Franzen
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Effect of temp on casting

#14

Post by Willy Franzen » Sun Feb 03, 2019 12:25 am

I always assumed that colder air temperatures would reduce distance because the air is denser, but I hadn't considered the stiffness of the line as a factor. It's pretty well understood that a baseball hit at the same exit velocity and trajectory flies farther in high temperatures than it does in low temperatures (about 3 feet for every 10 degrees of temperature increase). My guess would be that if you can control for the stiffness of the line, then a higher air temperature would give you more distance.

When I was casting with Steve Rajeff at the Sandy River Speyclave a few years ago (he was giving me an intro to comp casting), he mentioned that I shouldn't be disappointed to have less distance than I was used to getting because of the weather that day. If I remember correctly, he was more concerned with the humidity which was very near 100% than the 50-something Fahrenheit temp, but humid air is actually less dense than dry air (I just learned this!). So I don't know why a line would travel less far on a humid day. Maybe Steve was just trying to make me feel better about getting nervous casting in front of him.

Humidity apparently has a much smaller effect on air density than temperature does, so maybe it doesn't make much of a difference at all? I'm in over my head with this stuff already, since my initial hypothesis was that the drier air in winter (at least that's how it is where I live) might be the reason that some of you are experiencing better distance results in colder weather. But now I'm pretty sure that's wrong...

This all begs the question, would keeping your spools on ice in a cooler give you more distance in a comp? You may not be able to control air temperature, but you can certainly control the temperature (and stiffness) of the line for a short period of time.

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Effect of temp on casting

#15

Post by Paul Arden » Sun Feb 03, 2019 4:46 am

Jesus don’t say that Willy, now everyone will be carrying iceboxes around! At least it will help keep the beer cool :cool:

I’ve also read that air is less dense with humidity, but Ive really not noticed that in practise. In fact my very worst casting conditions are fog. So there is something missing in this argument - and I don’t know what it is.

I don’t think the Cumbria platform height offered any advantages in distance, James. It would had we been able to throw the backcast low, but because of the way the wind curved up behind the caster this wasn’t posssibe - in fact my backcast trajectory was higher than normal. If on the other hand we had a level field behind us it would have given us a major advantage and perhaps another 10 more feet. But this is speculation on my part.

Dealing with a swirling wind is always a challenge, Matt. Given the choice I woukd cast in no wind. Many years ago when I first started distance casting, when there was a wind we cast into it, or put it to the side. If we ever cast with it, then we would cast against it as well and split the difference. Back in those days casting with the wind was cheating :D

When casting with Rick in Texas sometimes his indoor hockey rink had hockey players on it. The insolence! And so once we went outside for a cast. It was windy and Rick wouldn’t cast because he didn’t want his technique affected. The Best of the West was indoors and that’s how he was going to practise!

Yeah Gary’s technique of carrying the whole line is hard to beat :D

Cheers, Paul
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Effect of temp on casting

#16

Post by guest » Sun Feb 03, 2019 8:27 am

Paul Arden wrote:
I’ve also read that air is less dense with humidity, but Ive really not noticed that in practise. In fact my very worst casting conditions are fog. So there is something missing in this argument - and I don’t know what it is.
The effect of air density is a collision between the line and the molecules in the atmosphere. If we think of the line as a white billiard ball travelling through the red billiard balls (air), the more red billiard balls there are the quicker the line slows down. So in dry air, you should cast further in less dense air, all else being equal.

If we remove half of the red balls and replace them with lighter but stickier blue balls (water molecules). Every time that there’s a collision between the white ball, we gain a blue ball and the line gets heavier. My guess is that the additional mass gained after loop formation is responsible for the line slowing down at a quicker rate than the dry line. Intuitively, I think it’s a function of the additional mass and the effects due to lower energy density rather than additional aerodynamic drag due to the wet line shape but it could be both.

Regards

Vince
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Effect of temp on casting

#17

Post by Boisker » Sun Feb 03, 2019 8:57 am

Interesting... relative humidity has been very low during the day the last couple of days, low to mid 70’s... so perhaps that’s the over riding difference I ‘may have felt’....

I say may as it was possibly just psychological in my case, with the orange line feeling/looking faster over the white background

Clear sunny skies again today, everywhere white with frost, little wind and low humidity... perfect winters day, off for a cast again shortly :D

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Effect of temp on casting

#18

Post by James9118 » Sun Feb 03, 2019 9:55 am

Hi Matt,

For me it's about 15mph with a #5, at that point I start losing carry i.e. the turn-over at the end of the back-cast starts to get a bit scruffy resulting in some slack unless I reign things in a bit.
Paul Arden wrote: I don’t think the Cumbria platform height offered any advantages in distance
I find it difficult to understand why some (you're not the only one) can't see why throwing something from a raised position goes further. Basic ballistics, however once I find a stable platform I'm going to do my best to get a figure for distance gained vs. height from which the cast is made. John Field has figures for this from ACA and ICSF events where the same outfit is cast, one from level ground and one from a platform.

With regard to air pressure, the first #5 cast I did over 130ft was when I was living in Albuquerque for a bit (1 mile elevation). I managed to increase my PB in that time to 140ft - it took me years of practice to eventually beat that in the UK and I wonder how far my cast would be going back in Abq after the technique improvement.

James

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Effect of temp on casting

#19

Post by Paul Arden » Sun Feb 03, 2019 10:06 am

Hi James,

Of course casting from a raised platform normally goes further! However because the wind was travelling down the lake from behind and below us, and then curving up from the bank behind us, I found it impossible to lower my backcast trajectory even to the same extent where I do from flat on the ground and was trying to get my backcast level with the rod tip and not angled below. Consequently the subsequent higher angled forward cast that I normally use was impossible.

If there was no wind it would have been different. If instead of the lower water behind us we had level land that would have been very different too. But in the situation we had I found lowering the backcast trajectory impossible.

Cheers, Paul
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Effect of temp on casting

#20

Post by Paul Arden » Sun Feb 03, 2019 10:10 am

This angle of forward trajectory is only possible by lowering the rear trajectory:
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