Welcome Bruce Richards

[VGB]

Vince, I'm sure Noel's test wouldn't meet your standards, but we had a small budget and only wanted to know one thing. The test was surprisingly simple, but it was obvious when I saw it that we'd get an accurate answer..
Bruce

Bruce

You wouldn't believe how low my standards are How are you selecting your textures, is it trial and error given the cost and complexity of this type of modelling or is there some science behind it?

Regards

Vince

[gordonjudd]

the smaller the diameter of a fly line is, the worse gets the relation between the amount of surface (friction) and mass.

Bernd,

How are you calculating surface area and mass per unit length?

I would think that the surface area and the linear mass density would both depend on the diameter squared.

Large dia. lines have less surface area (less drag) than smaller lines of the same density.

Bruce,
I don't think it is the relative amount of drag that is important because the bigger diameter line will have more surface area, but the relative mass that affects the sink rate. Is it form drag that is affecting this, not skin drag?

Gordy

[John Finn]

the more mass there is in the front of the line the later top leg acceleration will increase and the more energy is conserved, which will result in higher speed of larger diameter line at turnover, which turns over bigger flies better.

Hi Bruce , I have been following all these posts with great interest and have learned a lot.
Does it also follow that a weight forward would be better at turning over a long leader. I'm talking 3 and 4 wt lines here turning over 5 - 6 m leaders. Have been using mostly DT but recently tried a weight forward 3 wt and I think there was a difference. Very small flies with this set up.....................John

[Bruce Richards]

the smaller the diameter of a fly line is, the worse gets the relation between the amount of surface (friction) and mass.

Bernd,

How are you calculating surface area and mass per unit length?

I would think that the surface area and the linear mass density would both depend on the diameter squared.

Large dia. lines have less surface area (less drag) than smaller lines of the same density.

Bruce,
I don't think it is the relative amount of drag that is important because the bigger diameter line will have more surface area, but the relative mass that affects the sink rate. Is it form drag that is affecting this, not skin drag?

Gordy

Gordy,
As I said, the surface area to volume issue is definitely a minor player in this. Much more important is the mass profile of the line in question. More mass up front conserves more energy for later.
Bruce

[Bruce Richards]

the more mass there is in the front of the line the later top leg acceleration will increase and the more energy is conserved, which will result in higher speed of larger diameter line at turnover, which turns over bigger flies better.

Hi Bruce , I have been following all these posts with great interest and have learned a lot.
Does it also follow that a weight forward would be better at turning over a long leader. I'm talking 3 and 4 wt lines here turning over 5 - 6 m leaders. Have been using mostly DT but recently tried a weight forward 3 wt and I think there was a difference. Very small flies with this set up.....................John

Hi John,
Whether a line is DT or WF won't have any impact on how it might turn over a leader. If both DT and WF lines had the same front taper and tip diameter (assuming level bellies and same weight line), they will turnover and deliver the same. If you were to measure back 30 ft. on both lines and cut them, no one could tell you which was which. I think you might be looking at entire line profiles and see that it appears the WF would be heavier in front. Not the case, it's simply lighter in back. And in most fishing situations, the head of the WF line is rarely entirely out of the rod.
That said, not all DT and WF lines are made with the same front taper and tip diameter. Shorter tapers and larger tips will result in a more powerful delivery, but less delicate presentation. If you're looking to improve (more powerful) turnover it's easy to do with any line. Cutting a bit off the tip BOTH increases tip diameter and reduces taper length. Be careful though, not more than 6" at a time..
Bruce

[Bernd Ziesche]

How are you calculating surface area and mass per unit length?

Hi Gordy,
Bruce answered that question already, I think.
Otherwise I like this one:
http://www.analyzemath.com/Geometry_cal ... ustum.html

Hi Bruce,
I find it pretty hard to name any fly line to be a great distance line unless we have defined the conditions. That includes the caster's (casting) abilities, wind and the fly. If casting a heavy fly in heavy wind is our purpose I find the MED to be a disaster in terms of distance presentation.
If presenting a small dry fly on distance in no or little wind is the situation... I think the MED is a fantastic distance line.
Thanks for all your fine input about fly lines here. I (again) have safed some of your answers on my computer.
Cheers
Bernd

[John Finn]

I think you might be looking at entire line profiles and see that it appears the WF would be heavier in front. Not the case, it's simply lighter in back.

Does that mean that the weight of a whole WF line would be less than the equivalent DT.
Have checked the profiles of both lines and yes they are the same over the first 30 ft. Always assumed that the front end of the WF was heavier ie same tip but thicker belly . Thats another eyeopener for me ...........John

[Walter]

John,

Fly lines can be confusing. Many people also think sinking line weighs more than floating line. Fortunately we have people like Bruce who are willing to share their knowledge.

Walter

[Bruce Richards]

I think you might be looking at entire line profiles and see that it appears the WF would be heavier in front. Not the case, it's simply lighter in back.

Does that mean that the weight of a whole WF line would be less than the equivalent DT.
Have checked the profiles of both lines and yes they are the same over the first 30 ft. Always assumed that the front end of the WF was heavier ie same tip but thicker belly . Thats another eyeopener for me ...........John

Well, yes because the belly is much, much longer. But the total weight of the line is unimportant for the discussion at hand. It is the mass profile of the top leg of the loop that's important. When casting normal fishing distances, all that extra "DT weight" is still on your reel.
You say you've checked the profiles of both lines, but did you check the tip diameters? Two lines can have exactly the same front taper length but one be very delicate and one very powerful, depending on tip diameter/mass.
If the WF line you mention above had the same tip diameter as a similar DT line, but had a thicker belly, it would have to be a heavier line, like a 4 wt. instead of a 3 wt. But think about this, if I wanted to, I could easily make a 6 wt. line that would have a less powerful turnover and more delicate delivery (how the line lands on the water) than a 3 wt. There is no good reason to do that, but it could be done...
Bruce

[Bruce Richards]

How are you calculating surface area and mass per unit length?

Hi Gordy,
Bruce answered that question already, I think.
Otherwise I like this one:
http://www.analyzemath.com/Geometry_cal ... ustum.html

Hi Bruce,
I find it pretty hard to name any fly line to be a great distance line unless we have defined the conditions. That includes the caster's (casting) abilities, wind and the fly. If casting a heavy fly in heavy wind is our purpose I find the MED to be a disaster in terms of distance presentation.
If presenting a small dry fly on distance in no or little wind is the situation... I think the MED is a fantastic distance line.
Thanks for all your fine input about fly lines here. I (again) have safed some of your answers on my computer.
Cheers
Bernd

Good point Bernd, there is no one "best" distance line, there are many variables that would impact the design. The MED would not be my first choice for throwing heavy flies in strong wind. And distance is relative, for some casters the head length of the MED is too long so when they haul/shoot they still have rear taper in the guides. But it is the choice for many top casters. It doesn't really matter what the gear is as long as everyone uses the same. I've been in competitions where a soft 7' 2 wt rod was used because there wasn't much space for distance casting... The winning cast was still over 80 ft.!
Bruce