This Web page is based on Wayne Cattanach's Hexrod program, Rev 7-92,
which was graciously supplied by Wayne. It uses Web "forms" to
pass information between a set of cgi scripts written in Perl.
Wayne's Hexrod program was based on Everett Garrison's formulas,
published in "The Book".
I was also inspired by Bruce Conner's Windows version of Hexrod.
You can find an archive of information about cane rods, the Hexrod
program, and cane rod tapers at Jerry Foster's excellent
Rodmakers Web Site. Jerry's site has a paper by Wayne describing the
math behind the
I'll try to keep a list of modifications and fixes here:
- December 17, 1996: First released.
- May 2002: Complete rewrite of the program, adding many new
- June 2002: Decided to change how the user can input ferrule sizes,
making it easier for me an harder for the user :-(
- July 2002: Added the ability to set up private taper libraries.
- August 2007: Added option for DT or WF lines & more acccurate line weights
- Spring 2009: Major revisions, most important a rehosting to a commercial
web server and moving all rods and user libraries to a MySQL database. Details
of these changes can be found here.
- July 2015: Added options for 3/0, 2/0 and 0-weight lines; an All-in-One one-page
graph and table summary; and rod slope measures (Bokstrom RAV and LWV).
- September 2015: better support for metric data users and some simplification
- November 2015: Compute rod stress for a hollow rod.
How to use Web Hexrod
The Web page has two initial input screens.
The first is Basic Rod Design Parameters
On this screen, you enter the
rod geometry, choice of units
rod length, action length
line weight, number and size of ferrules, etc.
At the bottom of the first screen you make a choice of the Rod Data Input,
which takes you to the proper second screen. This is where you must enter
either Rod Dimensions
, or start with a
Once you have entered the dimensions or stresses,
the program does some checks for data consistency and hopefully will
find input problems and not just bomb or give stupid results. For instance,
rod dimensions must be in a reasonable range of 0.0 to 1.0 inches, but
if you enter a rod dimension of 184, it will assume you mean 0.184.
After the rod dimensions or stresses have been checked,
the program calculates the other and displays the Basic Design Report
the basic rod parameters and the dimensions and stresses at 5 inch intervals.
At the end of this report you have several options for getting more
detailed information or changing the analysis. These are your options:
- You can see the graph of the dimensions, stresses, or both combined
on a single graph.
- The Detailed Numbers table shows stress components at 1 inch intervals.
The Planing Form Settings table gives you the planing form station
depths at intervals of your choosing.
- Modify Rod Design
- If you modify the Dimensions, you can specify new dimensions at
every inch point.
If you modify the Stresses, you can specify new stresses at
every inch point.
modify rod fundamentals,
you can change rod length, ferrules,
geometry etc. This is discussed in more detail below.
You can Edit the Stress Curve, and change the stresses on a graph.
(This may not work well for you, if you have a slow internet connection.)
- Save the Rod
- This is described below.
- Described below.
Assumptions and Quirks
In converting Wayne's program, I made a couple simplifying assumptions which
I hope won't cause any grief. These were
- Most line weights come from the Cortland company website. See more info below.
Line weights cannot be changed by the user.
- Ferrules are assumed to be evenly spaced.
These are some gotcha's:
- I extrapolated Wayne's ferrule weights for some
larger and smaller sizes. Others contributed more ferrule sizes.
If you are
fussy, then weigh your ferrules. Then choose the ferrule size that most
closely matches the weight (see below.)
- If you go back and forth, calculating stresses from dimensions then
recalculating dimensions from stresses, the dimension values in the first
few inches of the rod tip get tiny. (This seems to happen in Wayne's
program also.) I did not try to determine what is going on there.
(Recall that Garrison did not use the dimensions near the tip from
his math either; he considered these computed dimensions impractically small.)
- Because of the way information is passed between program screens,
a browser "Reload" will sometimes bring back a screen without data. Use
the "Back" button to go back to a good screen, reload it, and go forward
again. This can affect how you correct entry errors; you may have to
return and fill in the entire screen again.
Some users experience problems getting an updated page or graph to load.
This is probably caused by your ISP serving an old (cached) version of the
page. You can usually force the updated page to load by pressing Ctrl-F5.
Another less elegant solution is to start Hexrod as a secure page with the HTTPS
This will generate dire warnings about Hexrod having no security certificate etc.,
but if you allow the exception for the website you will force the pages to load
Definitions of Terms and Descriptions of Special Features
Why can't we all just use the same units?
Hexrod allows specification of American (inches) or Metric (millimeters) for
three separate operations:
- Input of the rod (stations and dimensions)
- Output of tables and graphs
- Planing form settings
The length of
rod and the action length are input in American units (feet and inches) on
the first form page. After this point, you have the choice to input dimensions
and stations in inches or millimeters.
Planing form settings seem to be standardized on 5 inch (127mm) stations so these are
the default, and ferrule sizes are in 64'ths of inch, with metric sizes and weights
All input rod measurements, American or metric, are interpolated to 1-inch
segments for stress calculations and then back again to metric for display.
Ferrule size are in 64ths of inch and stress values are computed and
displayed in American (ounce-inches), as are Morgan hand mill settings,
at least for the present.
Its harder to explain than to use.
In case there is any confusion, the Rod Length
refers to the
entire assembled rod, from tip to butt. The Action Length
length from the tip to as far as you want to analyze dimensions and
The action length may end at the front of the grip, or may extend
into the grip and reel seat. It should never be longer than the rod length.
If you have a two-piece rod with unequal sections, you can analyze
it by cheating a little. Specify the action length as usual, but
specify the rod length as twice the tip length, whatever that is.
That will place the ferrule where it should be for the stress calculations.
As of August 31, 2007, separate line weights are used for DT
and WF lines. These were compiled/computed from the Cortland website by
Chris Carlin. They specify the weight of each foot of line for each taper
and line weight from 2 through 12. One-weight lines are extrapolated from 2-weight
data using the AFTMA line weight standards.
Previously, a more generic line weight was used, just by extrapolating
the weight of the first 30 feet (the AFTMA standard) over the entire length of
the line. The new more detailed line weight data provided by Chris
makes possible a more accurate estimate of both the weight
of line being cast and the weight of the line in
the guides, one of the components of stress. So users will see a change in
stress values with this switch to more detailed line weight info.
July 2015 line weights 3/0, 2/0 and 0 were added. These weights were extrapolated
from the data for 1-weight lines by using the info on Bill Byrd's website
www.byrdultrafly.com/sagelines.htm. To my knowledge, there are no AFTMA standards for these line weights.
For spey-type lines, enter the weight of the entire head section
(including any added tip)
and the length of the running line cast. E.g. for a 35-foot head section
and a 80 foot total cast, the running line cast is 80-35=45 feet.
There are many sorts of running lines on the market.
It is assumed to weight 3.0 grains per foot, which seems typical.
E.C. Powell tapers are created from a formula, starting with
"A", "B" or "C" families.
Powell "B" tapers start with a tip size and a linear taper,
given in thousanths of an inch per six inches of rod strip. E.g. a B-8 taper
has the strip increasing 0.008 per six inches (the total rod dimension
increasing 0.016 per six inches.) A B-9.2 taper increases 0.0092 per six inches.
"A" and "C" tapers modify the linear "B" taper formula by adding (A) or subtracting
(C) a fixed amount to the strip each 6 inches after the frist 6-inch station.
This amount is given as a fraction of a thousanth of an inch; 1/5 is 0.0002
An A-8 X 1/5 taper has the strip increasing 0.008 from the tip to six inches,
0.008+0.0002=0.0082 from six to 12 inches, 0.0084 from 12 to 18, 0.0086
from 18 to 24 inches, etc. Powell characterized the A-series rods as "progressive."
"C" tapers substract the fraction at each 6-inch station after the first. These
are "regressive" tapers.
Powell tapers are most commonly used for longer (8 foot plus)
rods in heavier (5+) line
weights, and are usually hiollow-built.
There is no fixed formula for choosing the initial tip size or
line weight of a rod. If you create a taper and take it into Hexrod, you can adjust
the line weight after viewing the stress values.
Input for Powell taper calculator is in American units. If you specified Metric
output, this will appear on subsequent screens.
The Hexrod implementation of Powell tapers is based on the article by Ed Hartzell
in The Planing Form, number 54 (1998).
There are many hollowing schemes in use. Hexrod assumes scalloping with dams
in its calculations. To determine the stress values for a hollow rod, you will need to enter the
distance from the tip where the hollowing begins, the wall thickness at that
point, and the wall thickness at the end of hollowing (usually at or just above
the action length.) It is assumed that the wall thickness changes in a linear
fashion between these start and end points.
The effect of hollowing on stress is hard to predict in advance. Hollowing
reduces weight of the rod (the "bamboo moment"); this reduces stress compared to
a solid rod, the difference increasing as you move toward the grip and becomes magnified
in longer (e.g. spey) rods. Countering this, hollowing
also decreases the stiffness (Modulus of Elasticity)
of the rod at each point; this increases stress values.
Which one of
these effects dominates depends on the degree of hollowing and length of the rod.
It is possible that stresses decrease in some areas of a rod while increasing in others.
Placement of ferrules can also affect how these two components
Most often, the effect of modest hollowing on
stress values is quite small for a trout-sized rod, but can be significant for a longer rod.
The formulas for stress in a hollow rod can be found in the toward the end of the
paper by Claude Freaner
on this website.
Some additional assumptions are as follows: Dams are assumed to occupy 10%
of the hollow, so weight reduction is only 90% of a completely hollow tube. There is no
hollowing within 2 inches of a ferrule location (no weight reduction there).
Computing dimensions while holding constant stresses (e.g. a hollow rod with the
curve as a solid rod) is an iterative process, working down the rod from tip to butt.
Iteration at an inch-point stops when stresses
are within 10 ounce/inches of
the target stress, or change in dimension is less than 0.0001 inches. Then
the process advances to the next inch. This will typically take a couple seconds.
Wall thicknesses at 5-inch intervals are given in the Planing Form Settings
Be aware that bamboo is not of uniform strength. Milward's book "Bamboo: Fact Fiction and Fly Rods" documents how rapidly the stiffness (Modulus of Elasticity) decreases
as you go from enamel to pith. Hollow building is removing much weaker material than
what remains. This fact does not enter into the stress calculations. Therefore,
building a hollow rod with equal stress to a solid rod will probably result in a stiffer
rod than you anticipate.
From the point of view of stress calculations, the only thing
about a ferrule that matters is its weight (and its location, of course).
Ferrule weights are supplied for sizes 8 thru 32 -64th in standard
and truncated lengths. They correspond most closely to nickel silver Super Swiss
style ferrules of the type produced by CSE. Some of the weights
come from Wayne's original program, from measurements others have
sent me, and from my own limited measurements. Some in-between sizes
I've estimated as best I could. (Yes, someone requested ferrules as
large as 32/64!)
If you are using a ferrule that is unusual in material, type or size.
and you know its weight in ounces, use the table below to choose
the size and type (standard or truncated) that most closely matches the
weight, and then use that ferrule "as if" it were the correct one.
Tell the program not to adjust the ferrule size.
Garrison incorporated this parameter (estimated to be 4.0) in his stress equations.
This number servs as a multiplier
for all the moments (line, bamboo, guide, varnish) to account
for the stress created by pulling the line through the air during the
cast. Increasing it will increase the stress values calculated.
Change it if you like, but make sure its the same when comparing stress numbers
of two rods.
The Tip Factor is the weight of the line beyond the tip
(and the weight of the tip guide, fwiw).
Garrison calculated the denisty of Tonkin cane as 0.668 ounces
per cubic inch. This parameter may be adjusted if you are
building with another material.
A private taper library lets you save your rods. Choose a library name (probably
something based on your name) and enter it. You will be asked for your
name and email address. After that things should be pretty self-explanatory.
In your library, you will give your rod a unique name called the Rod ID.
Both the library name and the Rod ID can be no longer than 40 characters.
We are all on the honor system here, so please don't try to guess
other people's library names and snoop at their tapers. OK?
If you have trouble with your library send me an email and I can probably sort it out.
If you have a lot of rods in your library, you can add a group name to rods to
cluster them together in the listing.
Examples would be "5 weights" or "3 piece" or "quad". The rod list will always
be sorted by this name. Within the rod group you can sort the rods by either Rod
ID or date.
One of the principal uses of the concept of rod stress is to assist in
designing a new rod from an existing rod.
With this program, you can modify one or more of these basic rod parameters:
- Rod Geometry (Hex, Penta, or Quad)
- Line weight
- Length of line cast
- Number of ferrules
- Type of ferrules
- Length of rod action
- Tip Impact Factor
- Cane Density
Then, you can rerun the program, holding constant
or the dimensions
This is the logic:
- If you want to try a different line weight,
or length of line cast,
then you perhaps want to hold the dimensions constant and see
how the stress values look under this change.
- Or, perhaps you want to find the dimensions of a rod that will
cast a different line with the same stress curve. In this case,
hold the stress curve constant.
- If you want to change the number or type of ferrules, then
you may want to hold the dimensions constant and see how the
stress values change.
- Or, perhaps you want to replicate the same stress curve in a
rod with a different number or type of ferrules. So hold
the stress curve constant and recompute dimensions.
- If you want to change the rod length, then
perhaps you want to replicate the rod's stress curve, but in a
longer or shorter rod. In this case, hold constant the stress curve.
- Or, perhaps you want to make a short rod from the two tip pieces of a
three-piece rod. In this case, hold constant the dimensions.
(Also, change the number of pieces from 3 to 2!)
When you change the action length, this is what happens:
- If you change the rod length and
hold the stress curve constant, the previous stress curve is uniformly stretched
or shrunk to the new rod action length.
- If you change the rod length
and hold the rod dimensions constant, the butt end of the action is
shortened by truncating (like when you slam the car trunk on the rod
butt) or by extrapolating the rod taper near the butt.
(If you want to shorten the rod at the tip, like when the screen door
closes too fast, this program cannot help. I'm sorry on both accounts.)
The critical thinker now asks, "If I am recomputing the rod dimensions,
say for a longer or heavier rod, how do I know what size the ferrules
Good question. If you hold constant the stress curve and recompute
dimensions, the program will iterate until it finds the correct ferrule
sizes for you. That is why the ferrule size boxes are blank. But if
you put in values, the program will use those ferrule sizes.
Sometimes it is useful to compare the stress curves or dimensions of
two rod designs, say before and after a modification. Enter the first
design and "Save" it, with a unique rod ID or name. Then develop the
new rod design and enter the rod ID of the saved rod in the "Compare"
box. The comparison shows the two rods side by side in tables and
It helps if the two rods have different descriptive names, since these are
used on the output.
Bill Harms and Tom Whittle explain Marinaro's taper graphs in their
book "Split and Glued by Vincent Marinaro" (Stony Creek Rods, 2007).
Marinaro designed his mostly 3-piece rods by considering the taper of each section
separately. The taper graph shows each section as compared to the overall
(start to end) taper slope for that section. Marinaro strived for what
he called a convex taper, with the mid and tip sections showing positive
deviation from the taper slope in the middle to upper end of the section.
See "Split and Glued.." for the details.
If you find any bugs, have suggestions for improvements, etc. let me
Just for the record, I promise not to peek at anyone's rod designs :)
Back to the Hexrod Program
"I'm not a programmer, but I play one at work."
Milwaukee, Wisconsin, USA