I have a 10' 6wt rod that I use for most of my fishing that I do. However I normally use it with a 7wt most of the time as I find this is easier to load the rod and cast with. However would using an over rated sinker be stretching the rods capabilities due to the extra pressure of the water?

Also does a heavier line help when casting into the wind or does the extra air resistance cancel out any extra momentum?

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Yes, I believe it does (so long as you don't increase the size of your loops). Some simple physics calculations also backs this up (posted in a similar thread a while back). There are some who think underlining is the way to go though. Using a higher density line (i.e. a sinker) of the correct rating will help into the wind.

With regard to the #7 line on a 10ft #6 rod - you should be ok depending on your style. If you start seeing tailing loops you'll have to open up your casting arc a bit until you get back to nice tight loops.

IMHO,you'll be ok up to a fast inter,when you get to faster lines(and what you expect them to do) you might slow the rod action below what you want from your rod.

Jim

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The Fishermans Friend is the Flirty Fly,Fickle Food for Fleeting Fish.

Try finding the thread James is talking about Al,its a few pages long but will answer all your questions and some.I was the one who bought up underlining not because i believe in it just that i was curious that's all,turned into a good debate

Neil

The mass of a fly line determined by the volume of the line, which varies with the cross sectional area and the length of the line. Air resistance is a function of the surface area of the fly line which varies with the line circumference and the fly line length. Length cancels out in both formulas since the two lines that are compared are of equal length.

So fly line mass is a function of cross sectional area which is a square function of the radius and Pi.

Area = (Pi)r2

Fly line circumference is a linear function of the radius and Pi.

circumference = 2(Pi)r

So when you compare the what happens when you increase line radius as a proxy for increasing air resistance, the line mass goes up much faster than the surface area. So mass increases faster than air resistance, which means kinetic energy increases faster than air resistance as we increase mass.

I may have posted those calculation in a reply to a poster who said fly line momentum decided how far a cast went. Here is my reply:

"Everything being equal, the heavier line will cast farther into the wind. For a moment, lets ignore rod actions, amount of line aerialized, and so on. If we make all these things equal, the heavier line will go further.

Although, previous posts have said that momentum detemines how far a line will travel against the wind, that is not quite true. A mass in motion has mass (M) and it has velocity (V). From these results two properties, momentum (P) and kinetic energy (KE). P = M x V and the KE = .5 M x V x V. Whereas P is a linear function of V, KE is a square function of V. The distance cast is not determined by KE and not P. This is the reason a double haul works to markedly increase the distance of a cast. A small increase in velocity results in a larger increase in the distance because the distance varies with the square of the velocity.

When an object is moved, work (W) is done. What causes the object is move is force (F). For a fly line in motion, the force that was applied has been transferred into KE. We can use KE as a proxy for the force applied to the fly line to get it to move. Now there must be an opposing force which causes the fly line to slow down. That opposing force is friction, which in this case is caused by the friction between the fly line and the molecules of air against which it is moving. We call this air resistance or wind resistance.

Air resistance is proportional to velocity and surface area. We can ignore velocity, since we said that the velocity of both the lighter and heavier line were equal. Then the determining factor is surface area. The heavier line has less surface area per gram of line than than the lighter line. Therefore, the air resistance per gram of mass is less for the heavier fly line. Since we said that the two lines started with equal velocities, the line with less opposing force per gram of line will go farther, and that is the heavier line."


When the poster was still not convinved I added the following:

"Momentum changes occur when two or more objects collide and the momentum of the objects are conserved. An example would be a car crash. See the physics explanation below:

http://www.physicsclassroom.co....html

However the distance of a fly cast does not involve collisions and the conservation and transfer of momentum. Distance fits into the Force/Work/Energy theorum and not the conservation of momentum theorum.

When we cast a fly line, we appy a FORCE to the fly line via the fly rod. The fly line is accelerated (moved) which produces WORK. The force we apply to the rod and the line not only produces work, but by causing motion in the line, it gives the line KINETIC ENERGY and by bending the rod, it gives the rod POTENTIAL ENERGY which is eventually also transfered to the fly line as additional velocity. KE and PE are forms of MECHANICAL ENERGY.

What causes the fly line to slow down and what determines the distance we cast is the opposing force of friction through air resistance. Friction is not momentum, it is a force. Gravity is also a force which pulls the line down but for the purposes of this discussion it can be ignored. When the force of friction finally decelerates and stops the fly line it has done the exactly the same amount of work that we did when we accelerated the fly line.

Force, work and energy are all interelated. Work is defined as the movement of a mass a given distance. Force is applied to the mass to do work. The greater the energy, the more force that can be applied. It is not momentum but the kinetic energy in the fly line that creates the fly line force opposing the frictional force. See the physics lessons below. The example of the decelerating car is similar to a fly line decelerating from the force of air resistance.

http://www.physicsclassroom.co...serve

A more practical example is the double haul. Why does it increase the distance of the cast out of proportion to the relative velocity increase that the haul provides? The major reason I believe is because it it increases the velocity, and even a slight increase in velocity results in relatively larger increase in KE because of the square effect.

And this from a casting site - see tip # 15 on the site below: "The faster the line is moving the more foot pounds of kinetic energy it has to carry it through the air resistance."

http://home.att.net/~slowsnap/tips3.htm

Here's some more good casting sites:

http://home.att.net/~slowsnap/tips3x1.htm

http://home.att.net/~slowsnap/biomechanics.htm

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Silver Creek- "Discovery consists of seeing what everybody has seen and thinking what nobody has thought"....Szent-Gyorgy

Some rods are wrongly rated...give your rod to an efficient caster and they'll no doubt tell you within one or two casts whether you need the 6wt, or the 7wt is fine...you won't break it overloading with 1 line size too heavy, the blank just won't recover fast enough to give you the power on your final stoke.

or here : Casting against the wind, and with the wind., post #29

that would be a yes then