Bamboo Tips - Tips Area
Rod Design - Cattanach Tapers

< Home < Tips Area < Rod Design < Cattanach Tapers

This kind of aimed at Wayne. Wayne, when you developed the different length tapers for the Sir D, did you do anything besides run it back and forth through Hexrod to get the stresses right? Reason I ask is that I would like to develop a 7'6" and possibly 8' version of a 7' taper that I've come up with and absolutely love. I realize that in lengthening it I am increasing the mass and affecting the casting characteristics. Is this something that is taken care of when dealing with the stresses or it more of a seat of the pants thing?  (Bill Walters)

Sit back with a cup of coffee and let's ponder the possibilities.

First thing to do would accurately determine the true line weight and distance at which the rod you wish to duplicate maximizes. By that I don't mean where it totally collapses but where it can be comfortably push too. Then take this information and input into Hexrod. From that you will get your base stresses. Now remember that the casting action of a 7' rod is usually 74". Now Hexrod can work by the inch but at some point there needs to be some foreshortening or slight stretch to match with your planing forms which I am assuming are set at 5" centers. So the recommendation would be to go for the 75" at this point.

Now you have a set of numbers that may not mean a lot to you. So the next step would be to graph them. I know that there are several "scales" that different folks use but . . .in any of them you will see areas where the curve seem to flatten or at on a uniform rise or decline. Those are the areas that may be considered later for adding the needed action lengths for your desired  . .stretch of the rod. But there are some other insights you might consider.

If you have read Mr. Garrisons thoughts on rod design he talked of the "wave" action. In as simple terms as I can share it simply means that if a fly rod were held outright and twitched(a light raise and lower of the wrist). This action would set the rod into a harmonic (movement) that would must resemble that of a sine wave with the tip and but in fall as the midsection was in a rise and vice versa. The points at which the rod would seem fix would then be the 3rd and 5th harmonic which would reasonable occur at point close to the 1/3 and 2/3 dimension  points of the rod. This is why some feel that a 3 piece rod casts smoother than a 2 piece rod. Due to the ferrules located to places where the energy passing through the rod is in a more neutral wave state. ya ya ya (I hear you - this is getting to  be way TMI - too much information).

Now unless there are severe graphic changes occurring at the points that represent the 1/3 and 2/3 rod lengths. I have added the needed extra length in  stretching a rod graph at those points.

Specific to your needs try this. on the stretch from a 7' (84") rod to a 7' 6' (90") rod add 5" after the 25" (from the tip). In other words make a new point 30" - and move the 30" value and all following values 5" further down the graph. Then to an average of the 25" value and the now 35" value and assign that value to the new 30" point. This now give you a rod action length of 80".

In the same manner, to step this rod design now from 7'6" (90') to 8' add a new point at 60". Moving the old 60" point to 65" and so on down the end. Again do a value average of point 55" and 65" and assign that value to you new 60" point.

I when stretching the Sir D did just as above. But . . there is another method that has some merit as well. When using the old graph (rod action length - 75") and inputting values for new graph (rod action length - 80") skip 1" every 15". This can be a bit tedious. Remember Hexrod is designed to use however many entries you wish to input. If you only put values in a 5" increments it creates the midpoint numbers from you input. IF and some folks don't realize this with my version. You put number in a all or most of the 1" increment values - it(Hexrod) will use those values and only calculate the missing values.

Then using the same concept to stretch the 7' (84") rod to the 8' (96") design. Again the rod action length of the base would be 75" and the action length of the new design would be 85" you would need to add in 10 steps which is about every 7th input value.

I know this is trying to share some complex ideas without the use of visuals but I think I have explained it right. If I haven't let me know and I will as some times needed alter the way I think to try to make it more understandable to other.  (Wayne Cattanach)

OK . . so after a few more sips of coffee and trying to read what I just wrote. I do need that 3rd line in the glasses these day. I have said this to some yet I thought I might just pass it along as well.

I fell that a stress graph should be referred to as a character graph. I represents a character of a particular rod action. I also feel that that character can be applied to a #2 weight rod just as it could to a #6 weight rod. BUT obviously the force needed to make that larger system work would be increased. AND that that larger amount of force seems to throw off some peoples thinking.

An example would be this . . . if a rod roll casts well the "character" of that rod should be able to be applied to a varying array of rods. AND all should roll cast well.

I hope that makes sense to all. I have lost folks in that understanding at times and I don't mean to. Some perceive stress graphs being assigned to a specific rod weight where should be viewed as a  . . . Character that could apply to all weights.  (Wayne Cattanach)

Good explanation. Yep, once you get to the "J" on your funny looking graphs, it'll cast just fine!  (Larry Blan)

If your only interest were designing a rod that roll cast well, what would the stress graph or taper look like?  (Bob Milardo)

Look at the stress graph for the Cattanach 7042. The peak at the 55 inch station makes that rod a good roll caster. I made this rod without that peak and it doesn't roll cast at all. I can get it to roll cast, but it takes a lot of effort and concentration, moving my hand up and down just right as I start the roll cast. With the peak it roll casts easily. I call it the Cattanach Hinge, but that may not be a good name since the word "hinge" has bad connotations to some people in fly fishing.  (Darryl Hayashida)

Regarding your question on changing the length of a taper, I think it really depends on the rod taper itself. No matter where you lengthen it ,the action will change somehow. therefore the object is to put the change at a point on the taper which will change the action the least, and I don't think you can do that until you look at the specific taper and try to decide where that point should be. Some tapers will allow themselves to be lengthened or shortened without changing the action and some will not. So I think the decision is up to you and your feel for what the action is. As a suggestion; If you want to lengthen it by 5" pick one station which has  the least chance of changing things, if you want to increase by 10", pick them so that they are spaced apart by 15-25".  (Bob Norwood)