I think I know the answer to this question, but I would rather ask those with a lot more experience and knowledge in the matter. I had a request for a 20 ft long trolling rod for crappie. This gentleman said that he would rather have something very stiff except for the last 4-5 feet of the rod. He said the present rods offered in this length are too soft in the mid sections of the blank. He wants to have a longer rod so he can spread out his rods without spider rigging and without the use of planer boards(which he is vehemently against). I know that I can lengthen a rod blank by adding to the butt section, but most rods in this length have too much of a parabolic action for his liking. So I was wondering if I could find a similar tapered blank, run it up inside the other blank and stiffen the mid-section of the rod? Will this cause a fulcrum effect and the tip of the inner rod make a shearing point for the rod to break at the terminal end of the inner blank? Or are there some type of extra (extra) long blanks that I'm not considering? Thanks in advance.

It depends on just how stiff the internal section is. Yes, there will be a point along the two blanks where you'll have a stress riser where the insert ends. If the insert there is fairly flexible or if you do some sanding to thin it down a bit, you can at least reduce the sudden stress concentration, to some degree. Even then, you'd have to do this for some distance to smooth out the transition. Obviously, this sort of thing can get really involved. On the other hand, the particular blank you're working with might be able to withstand it. People do crazier things and often manage to get by with it. There's just a lot of variables here in terms of the various blanks, inserts, etc., to really offer a definitive answer as to whether you can make it work the way your customer wants.

Some of the Match or Coarse rods sold in the European market might be a better choice, provided they're tapered along the lines of what your customer is looking for.

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One way to go, is to pick up a long trolling rod, and then use a long trolling rod holder to extend the rod as far as you wish.

For example:

[www.basspro.com]

Here is a 16 foot trolling rod. You could mount a 5 foot long rod holder on the boat, such that the end of the rod would slip into the rod holder by a foot. Then the end of the rod is 20 feet out from the boat. When it comes time to catch the fish, pull in the rod holder and grab the rod.

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Here is the rod that I was thinking about. This is the Crappie tight line fishing rod. It is advertised as a medium heavy rod, which it is in the butt section. But there is a bit of softness in the tip.
This is an 18 foot rod, that does exactly what your client wants. Quite a few years ago, I purchased several of these rods and used them for long rod crappie fishing and they worked out very well. But over time someone else wanted them more than I, so I sold them to the other person. But I do believe that this rod would exactly meet the needs of your client.

[www.basspro.com]

Good luck

I don't have any experience with 20 ft rods but if stiffness for the 3/4 of the length is required I would suggest You get a telescoping aluminum handle that one uses for sweeping pools and adapt the blank to the end of it using sleeves between the blank and aluminum handle. 13 feet would be stiff aluminum and the remainder would be a standard blank.

Thank you Tom, I was thinking that a "Frankenstein" rod would be one of the only ways to go. You bring up a good point on the euro match and coarse rods. I'm admittedly not familiar with them, but have been looking a little at them since your suggestion. I'm thinking that this fellow wanted off "on the cheap" and don't think he would be anywhere willing to pay for the amount of work that could potentially be involved. That plus the fact that it very easily could turn into multiple trial and error builds and "ruining" the internal blank(s) by sanding them down.

Roger, that 18 footer with an extension is a fantastic idea and I might just point him toward the basspro rod.

John, that sounds like a fantastic "Frankenstein" rod. I definitely wouldn't chalk it up as a "pretty" build, but dependent on how badly he wants to try something...necessity is the mother of invention.
Thanks to all of you.

Jared,
I really think that if he had the 18 foot rod, he would find the length adequate and not have the need for it to be two feet longer.

Be safe

Thanks Roger, I think you're correct, if it has enough "oomph" in the mid, it should do just fine without the extension.