Advice on Shortening a blank

[Willo]

I have a 7,6" Looms saltwater Blank rated 20 -30LB
I want to shorten this blank to 7ft and make it into a 30lb plus Spin for a Stella 10000
The plan is to take a bit from the tip and some from the butt,to get the 7ft lenght and stiffen it up a bit. I know shortening from the tip stiffens the action ,and shorting from the Butt has not much effect on the action of the blank
Is there ant set formular for this type of thing ? or any advice on the correct way to go about it
Willo

[Owen]

Willo,
I don't think you're going to notice a huge difference.
You can see for yourself by doing the following.

Put two pegs in the wall or a board at the distance between the butt and where your front grip is.
Tape your blank to it so that the butt is under one and over the other so that they support the blank as you apply weight.

secure a weight to the tip and mark the curve on your wall/board.

Now move the blank back however much you plan to cut off the butt and re-tape it to the pegs.
Hang the same weight from the blank, but come in from the tip the disctance you plan to cut off the tip end.

Re-trace the curve and you'll get a reasonable approximation of the change you can expect.

First image is original blank.

Second image is re-set to where you want to cut

[Willo]

Thanks for that great info Owen,just what I was after
Cheers Willo

[Tim Robinson]

I'm about to do this also and have been wondering the same question. Thanks Owen from me also.
Tim

[Owen]

There are of course a hundred variables as to exactly how each option performs once wrapped.
This is just a method of getting some sort of comparative measurement.

you could vary it in many ways.

e.g.
You could apply a known weight/force (say 1/3 the line rating) using a spring scale and measure the deflection on the unmodified blank.
Then you could shift the blank and weight hookup points and measure how much force is required to deflect the blank the same amount.
The figures most likely won't equate to what the blank manufacturer rated the blank at, but they'll demonstrate the changes occuring in a unit that's understandable.

At the end of the day though, I think you still have to do some subjective "feel" testing to make sure you didn't just turn your bream rod into a broom stick.