It’s useless for people like David and others who are measuring IP in grams or cents for their blanks and would like to know how these numbers compare to IPs of other blanks. For example, when given an ERN of 25.1 how does one compare this number to an IP value measured in grams or cents? Unless he has a conversion chart or a conversion program he has no ides that an ERN of 25.1 is equal to 764.09 gm or 305.64 pennies. In other words, ERN is a number converted from an IP number by a conversion formula, and unless he can do the conversion it is not of much use when wanting to directly compare IP values.
Norm

Norman,

You compare ERN to ERN, not IP. A rod with an ERN of 5 is less powerful than a rod with an ERN of 6.

You do not need to know how many pennies, grams or whatever - that has nothing to do with the blank's power. That is simply the weight required to take the measurement - it is not how much weight the blank will cast or deadlift.

.......

Mike B, ERN didn’t come first it was derived from the measured IP of a blank in grains to reflect a relative fly line weight. I know that the first 30’ of an 8 wgt fly line weighs more than the first 30’ of a 7 wgt fly line, but can you tell me what the difference is in grains, grams or cents?
Norm

Norman, I will definitely take you up on your offer and be sending you an e mail tomorrow. Thank you.

Tom, if I may ....... you are speaking from a strictly for comparison stand point. As such, you are correct .... as long as we are all using the same numbers, and the same names for those numbers, then what the number equates to or what it's called isn't important at all. But everything isn't for comparison sake. Have you never weighed a fish to see how much it weighed? Or measured something to see how long it is?

If I want to how much weight it takes to bend a rod a certain amount .... an IP using an ERN number is going to tell me nothing. What if I want to match the power of a factory rod I have? How do I measure it? How do they tell the difference between a 3 weight and a 4 weight fly line? By its' weight, correct? So clearly ERN is based on a weight. I can relate to measurements in weight. And if it's given in something I am unfamiliar with, I can convert it to something I am familiar with.

You do it by not converting - just use ERN. Measure your factory rod and get the ERN number. Now match it by finding another blank with the same ERN number. The power will be the same.

Dr. Hanneman attempted to take "weight" out of the equation to make things easier... which it does. You were not born with an inherent knowledge of how long an inch is, or how much weight constitutes a pound. You had to get familiar with them. So, too, with ERN. With just a little practice you will get the idea of how much power a unit of ERN represents.

And yes, ERN came prior to IP, by several years. I published the articles and know the timeline. ERN is not based on fly line weight.

..............

Tom, I know what you are saying, but you are not seeing my point. If a manufacturer lists the power of their blanks by ERN (asPoint Blank does) then how does one compare that ERN number to their favorite blank which they personally measured it’s IP in grams. Like ERN , the higher the IP the more powerful the blank, thus IP to IP measurements are a valid way to compare blank power. In my opinion IP is more useful than ERN because you have a direct measurable weight which does not need to be artificially converted to another number.. IP to IP comparisons cuts out the middle man, so to say.
Norm

Pretty sure that ERN is a relative rod power number, not a fly line weight.

Norm,

But it's the same thing - ERN to ERN keeps you from having to convert to IP, thus cutting out the middle man. They're both the same thing, just different numbers being assigned to some amount of rod power. The actual weight required to attain the measurement standard has nothing to do with anything - It's not the weight the rod can cast, deadlift, etc. Just the standard required to the rod power number, whether it be ERN or IP. The IP figure was derived from ERN to begin with. Either way, there is never any reason to have to convert ERN to something else. Just use ERN (or use IP if you like that number). With ERN, you don't have to bother with grams, grains, etc., you can use pennies which nearly everybody has readily available and which, since 1986, have been maintained at the same weight. That's why Dr. Hanneman called the system the Common Cents System. His goal was to make things easy and part of making it easy was to cut out the necessity of weighing anything. You just count the pennies required to get the deflection amount and read the corresponding ERN figure. The actual weight in grams or grains or ounces, does not matter.

........

Mike,

You are correct. ERN is a relative measure of rod power, not a fly line weight.

.........

The use of pennies instead of having to weigh something was genius in my opinion. It is still weight but does not require having to weigh anything. It is built in to the system and resulting ERN.

We are probably getting off topic a bit but yes, the idea to use pennies as a weight standard was brilliant. I have spent hours talking to Dr. Hanneman and he is one of the most intelligent and clever people I've ever met.

There is a story behind why Dr. Hanneman used IP for reference in the Universal Rod Rating System along with ERN but I'll save that for another time when it isn't so late and I'm not so tired.

So just as some people mix their epoxy by weight, weight per factor, etc. others just mix 1 to 1 by volume. Whatever you like the best use that and never convert. There is no need.

.............

You have to have a conversion chart or formula to convert IP to ERN or vice versa. The formula was not given in the common cents articles and the conversion chart given only goes up to an IP = 62 cents as being an ERN of 7.9. Thus, it rather difficult for someone to do the conversions from IP to ERN and vice versa. Also changes in IP are not proportional to changes in ERN. For example, the change in IP between an ERN 4 to an ERN 5 is about 16 gm, the change from ERN 7 to ERN 8 is about 20 gm, and the change from ERN 20 to ERN 21 is about 36 gms. These differences are not exactly intuitive. This is the reason why I always post CCS IP numbers vs ERN here on rod board, because I know the people interested can make the direct comparisons with the blanks they measured. You can’t measure ERN directly, you have to measure IP first and then convert. That my educated opinion and I’m sticking to it.
Norm



Edited 1 time(s). Last edit at 05/26/2020 09:39PM by Norman Miller.

I still don't understand the need to convert. ERN is rod power. Use ERN. Or just use IP. Why is there any need to convert between the two? I have never measured IP - my measurements give me a direct ERN figure which then allows for direct comparisons.

..............

I have never needed to convert from IP to get the ERN either. It may depend on which chart a person is using. I just dropped pennies into the tip bag and count them as they go in. Then go to the chart and get the direct ERN figure. I think there was a later chart that allowed people to take weight measurements instead of just using pennies and that one may be the one that has the term IP on it. At any rate I am not going to the trouble of weighing anything. I have small bags of clustered pennies, some with 20, some with 10, some with five, and then just four individual pennies. I can get the deflection in an instant and do not need to know anything about what anything weighs. The chart lists the direct ERN for the number of pennies But I think there is a later chart that uses weight and IP even though they amount to the same thing.

Then tell me, when you personally do a CCS analysis in your shop on a rod blank from a manufacturer that does not give ERN values how do you directly measure ERN? The answer is you don’t! You measure the weight (in cents or grains or grams) required to bend the blank 1/3 it’s total length. This weight is the intrinsic power (IP) of the blank. To get the effective rod number (ERN) you have to convert the IP to an ERN number, and unless you have a conversion table or formula one would have no idea how to do it. It is not intuitive. You can’t directly measure ERN, you have to measure the IP first. ERN was an arbitrary way devised by Dr Hanneman to relate IP to something in the real world such the once standard weight of the first 30’ ft of fly line in the various weight categories. ERN is a calculated value not a measured value. I have read the CCS articles many times, and there is no direct measurement for ERN given anywhere in those articles.
Norm

ERN is not related to fly line weight. It is somewhat possible to relate fly line weight to ERN, however, although this is not ironclad. And you could also relate fly line weight to IP, but that is also not ironclad. Not everyone fishes at the same distance nor casts the same way.

Dr. Hanneman removed the necessity of weighing anything by cleverly using the U.S. Cent for the weight standard. You only had to count the number of pennies to get the ERN. The CCS includes the Rosetta Stone chart as part of the system. Some people would simply say they had a "43 penny rod" instead of stating the actual ERN for the rod. Same thing that many do with IP now. As long as each person is comparing with the same figure, it works. The idea behind ERN was to supply a power rating based on whole numbers similar to what most all blank manufacturers already had in place, but one that was the same across the board from company to company (most proprietary power systems are not transferrable from one company to the next. One company's 4-power rod may be another company's "5-power" rod).

The idea of IP for a power rating was introduced several years after the CCS was unveiled in what is known as the Universal Rod Rating System. It also included a chart which was the first time that IP was included.

.........

Since it does not require me to weigh anything I will stick with the common cents system. There is no math required to get the ERN, you just look at the chart. I am all for whatever is easiest quickest And for me personally that is the common cents system.

The is the URRS chart which corresponds to ERN, TP and PR. Note that IP is not included as a power measurement number, although actual weight is included in the chart for those that do want to use IP for the power number.

[www.rodbuilding.org]

.............

I get it but the requirement or necessity to have to weigh something when that work has already been done for you just does not make sense to me. Sense as in sense not cents. And if you are using pennies anyway, then converting pennies to IP is no easier than converting those same pennies to ERN. Takes two seconds either way.

True, but some people would rather use something other than pennies and then weigh the amount used. It's an extra step but it's up to the individual user to decide what method they like best. In the end, they deliver the same results. The inventor of the system intended ERN be used for the relative power figure. But you can use whatever you like. They're all relative.

...............

PS - I compiled all the Rosetta Stone charts and the last one I did was obviously the most expanded, but I'll have to go back and find it. I thought it was in the library here but it's not. I'll look for it in my files. It doesn't have any IP values listed, however.

...............