CarpForum Thread : TC and controling fish : Carp Fishing Forum




[Log-In] or [Register]	Advertise to thousands of anglers a day! Click HERE to see how



Home	Search		Help / FAQs	Rules / Usage

Who's Online	Member List	Articles	Gallery	Weather

Site: 0 unread posts

TC and controling fish	5,065 views
[Log-In] [Register]

essesxandy

Posts: 3162

#49 30 Aug 2026 at 8.37am

In reply to Post #46
So basically the science backs up what most experienced anglers already though, that lower TC, through action rods absorb the lunges from the carp which will undoubtedly result in fewer hookpulls.

MrGreen

Posts: 192

#48 26 Aug 2026 at 9.35pm

In reply to Post #47
Agree.

That’s why I posted it because there’s a lot of factors that have to be considered. This example obviously just gives two examples of available rods to demonstrate the calculations.

ip100

Posts: 12486

#47 26 Aug 2026 at 11.37am

In reply to Post #46
There is a very big assumption in that, and that is the lower TC rod has a softer action which inturn shortens the lever effect. But this isn't always the case. You can get faster actioned lower TC rods , you can also get softer actioned higher TC rods. As an example a 3.5lb aviator compared to a 4lb ballista. The ballista is the smoother through actioned rod whereas the aviator is a much faster tippier rod. There's only 0.5lb difference in TC, but a much more noticeable difference in action. Also how a blank is rung makes a difference too, an identical blank can act pretty differently depending on the ringing pattern

MrGreen

Posts: 192

#46 26 Aug 2026 at 11.08am

In reply to Post #1
This got me thinking because some of the videos mentioned in this thread only test one force and don’t mention the multiple scientific properties involved in a fishing rod as a lever and a spring.

Here’s some of the scientific data:

We have to look at the physics of a fishing rod, which operates as a Class 3 lever, combined with the concept of spring constants and Hooke’s Law. Here is the deep scientific breakdown of how test curve, leverage, and force transmission interact during a fight.

1. The Fishing Rod as a Class 3 Lever

In physics, a fishing rod is a Class 3 lever.

The Fulcrum: Your pivoting hand (usually the bottom hand on the handle).
The Effort Force: Your dominant hand pushing or pulling just above the reel.
The Load Force: The hooked fish pulling at the tip of the rod.

In a Class 3 lever, the Mechanical Advantage (MA) is always less than 1. This means you must apply more effort force at the handle than the load force exerted on the fish.

Because a lower test curve rod bends much deeper into the handle (often called a "through-action" or parabolic action), it shortens the effective straight-line distance between your hands and the bend of the rod. However, because it is softer, the rod absorbs the load by compressing, requiring your wrists to work much harder to keep the tip up. A stiffer, higher test curve rod maintains its structural rigidity in the bottom half, meaning the lever does not collapse under load, giving you better mechanical leverage to dictate the direction of the fish.

2. Force Transmission and Hooke's Law

A carbon fiber fishing rod acts like a complex spring. Under ideal conditions, it follows Hooke’s Law (F = kx), where:

F - is the force applied.
k - is the spring constant (the stiffness of the carbon blank).
x - is the displacement (how far the rod bends).

A 3.5lb test curve rod has a much higher spring constant (k) than a 2.5lb test curve rod.

Because of this higher stiffness, the 3.5lb rod can store and transmit a much higher peak force. If a fish lunges suddenly, a soft 2.5lb rod will simply flex further (x) increases) to absorb the kinetic energy, keeping the force (F) relatively stable. A stiff 3.5lb rod will not flex as easily; therefore, that sudden kinetic energy from the fish is instantly converted into a sharp, massive spike in tension (F) along the line.

3. The "Bottom Out" Phenomenon (Elastic Limit)

Every rod has a maximum curve it can achieve before it "bottoms out"—the point where the blank is fully compressed and can no longer bend. At this point, the rod ceases to act like a dynamic spring and begins to behave like a solid, rigid stick.

On a 2.5lb rod: You reach this ceiling very quickly. Once the rod is fully bent, any extra force you apply bypasses the rod's cushioning completely and is transferred 1:1 to the hook hold and line. Because the ceiling is low, the maximum pressure you can physically apply before risking structural failure or a line snap is heavily limited.

On a 3.5lb rod: The ceiling is vastly higher. You can pull with immense force before the blank fully bottoms out, allowing you to exert high-power stopping pressure on a fish trying to reach a snag.

Soft Rod (Low Test Curve):

Spring Constant (k) - Low - Easily displaced by low forces.
Energy Absorption - High - Acts as a dampener, smoothing out kinetic energy spikes from the fish.
Peak Force Potential - Low - The rod cushions the blow, capping the immediate load on the hook.
Static vs. Dynamic Tension - Maintains highly consistent dynamic tension, even as the fish changes velocity.

Stiff Rod (High Test Curve)

Spring Constant (k) - High - requires massive force to displace.
Energy Absorption - Low - Transmits kinetic energy directly and immediately to the line.
Peak Force Potential - High - Can deliver heavy, instantaneous loads to the fish's mouth.
Static vs. Dynamic Tension - Creates volatile static tension; force drops quickly when the fish slows, and spikes when it runs.

The science proves that a higher test curve rod exerts more absolute physical pressure.

The reason anglers think lower test curve rods exert more pressure is psychological and sensory: because the soft rod turns into a poor lever for the human arm, the angler feels immense strain in their wrist and assumes the fish is feeling the same. In reality, the rod is cushioning the fish, while a stiffer rod would be punishing it.

tommo7567

Posts: 23

#45 10 Aug 2026 at 8.31pm

Coming from a barbel anglers perspective, test curves tend to give us a guide as to what conditions a rod is more suited to, rather than the size of the fish targeted. Balanced tackle being more relevant, the old rod tc over line breaking strain seems to work well. Although that doesn't necessarily take into account snags etc.

It also doesn't account for the drag of the reel being used. I have a few(!) barbel rods of different brands and tc's from 1 1/4 to 2.5lb. Some suit smaller rivers, others are for floods etc. The one thing they all have in common is the ability to play a fish and stop it before the rod locks up. The only way I've found of doing this is to set the reel clutch, whatever the reel is, by tying up a complete rig on the bank before fishing, and hooking up to a ring or zip on my bag. Then gently lifting into it until I feel the rod begin to lock up. At this point I'll turn the drag know so it just about gives line.

I'm not claiming barbel don't take line because they will, and when I feel i can let them during the fight in mid river they can, but this method of setting the balance of the rod and line and clutch means you can give maximum power at the beginning of the fight to gain control at the start. It's not perfect but I'd say it works the vast majority of the time.

JasonM

Posts: 1764

#44 4 Aug 2026 at 3.04pm

Adding to below and a shared opinion test curve etc is irrelevant its mindset

90% of the time the problem is folk are not close enough to there rods and not brutal enough in controlling the carp.
As soon as hooked up close to snags you have to be stepping back to drag it away from the snag with clutch completely locked up.

Over the years I watched on small rivers folk like Dave Currell catch big barbel including the lady. He always told me if you give anything you deserve to loose.

crazycarper92

Posts: 112

#43 4 Aug 2026 at 1.47pm

In reply to Post #42
Exactly, the setup is to suit requirements.

But, how many 16 year olds are fishing for doubles in farm ponds with 3.5 - 4lb tc? Utterly ridiculous imo I’d rather use a float rod!

MrNuvawun

Posts: 2414

#42 3 Aug 2026 at 11.42pm

In reply to Post #41
My main 4 rod setup are 12ft CFX Continentals, they don’t have a test curve as such, but are rated at 3-5oz casting weight, with a firm progressive action. Only reason I’ve got such heavy rods is because I fish a great big reservoir, where you can have massive winds blowing from any direction, making casting accurately at any sort of distance during the day, nigh on impossible and because of that, would quite often wait until the evening to cast out. I was wasting so much of my bank time not actually fishing. Heavier rods, capable of punching out heavier leads on heavier lines is the way forward during the summer months with 16hrs+ of strong winds at times. In the spring and autumn months (I don’t do winters anymore) I change over to my 3 rod setup of 12ft 3.25lb CFX’s, which to be honest are much nicer to play fish on. That said, the progressive action of the Continentals is a good compromise over a fast taper, out and out distance rod and the playing action is acceptable, albeit with slightly less control than the 3.25’s.

crazycarper92

Posts: 112

#41 3 Aug 2026 at 10.12pm

In reply to Post #38
Bang on, although the lower TC rod puts ‘more’ pressure on in general, you’ve got way more margin for error through give in the rod when playing the fish. 4lb broom handle when a fish powers off on a lunge? Far less give, far less margin of error.

Also worth noting when the weed is up, TH uses old rods with more give in them. The reason, to use that to exert pressure on the fish itself, rather than hoiking the whole lot through including half the weedbed itself as you would a 4lb TC rod.

Horses for courses and each to their own, but I think this push into higher test curves is in part brands, and in part to accommodate the divvys who want to cast 6oz leads in farm ponds.

I cannot imagine 10ft 4lb rods are much fun playing a fish in comparison to the chap above on his ballistas

ip100

Posts: 12486

#40 3 Aug 2026 at 9.34pm

In reply to Post #39
Realistically you don't, it's just tackle companies convincing us we do

DenzelLN

Posts: 372

#39 3 Aug 2026 at 6.30pm

In reply to Post #36
True, I just cant imagine a situation where'd id need 4lb TC rods I guess.

essesxandy

Posts: 3162

#38 2 Aug 2026 at 9.31am

In reply to Post #10
I fully understand what he's saying, but, and it's a huge but, all of the guys that have suffered multiple 'hook pulls' at my place, over eleven years, have been using higher TC and/or fast taper rods. Absolute fact.
I'm not the only one who has noticed it either.
Use a 2.5tc Baby Ballista and you will 100% suffer fewer 'hook pulls' than if you use FMJ's

j-d

Posts: 30

#37 2 Aug 2026 at 8.23am

In reply to Post #34
Depends what your situation is, if I'm flicking chods about in winter and spring the weed is all dead and I'll use 10ft 3lb scopes, the furthest I'm casting is 13-17 wraps so that's fine but when the Canadian is up having those extra beans is a good thing, average fish in there is low 30, loads of Canadian solid bags

vossy1

Posts: 8987

MODERATOR

#36 1 Aug 2026 at 2.36pm

Better to have it and not need it, than to need it and not have it.
The trade off is worth it in my eyes.

0nslow

Posts: 1593

#35 1 Aug 2026 at 2.21pm

I've used my R1FT'S for the first time this weekend.

I wasn't casting big distances under arm flicks. But the two fish I had were buried in weed and one had to get pulled away from a snag.

3.5tc performed admirably and I felt in control all the way. Horses for courses I suppose, but I was happy to have the extra backbone for sure.

Incredible blanks 👌


	Page: 1 of 4




Stickies General Discussion Sponsor Posts/Updates CarpForum FishIns Tackle Reviews Rigs Bait Catch Results Venues (UK) Venues (Foreign) Classifieds FAQs and Help Feedback to CarpForum NON Carp Stuff	Proven, Quality Carp Baits from DNA Baits Carp Syndicates Croxley Hall Fisheries Lake Exclusive France Redwood Lake Consent Preferences Advertising disclosure
� Copyright 2002-2026 - www.CarpForum.co.uk	contact : webmaster@carpforum.co.uk