Scroll To Top

Matt explains the criteria to consider when choosing the best carp line for different lakes and waters

Note: Check out my other post on the best mainline for carp fishing to read the reviews of my favourite and least favourite lines for different angling situations.

How to choose the best carp line

When it comes to picking what fishing line to use for carp, the choice is bewildering. The manufacturers all proclaim their line is the best and the customer actually has very little to go on. So how do we sort the wood from the trees? Many people look through the opinions of their fellow anglers in the carp fishing forums with questions like:

  • What mainline for France?
  • Best mainline for weed?
  • What mainline for big carp?
  • What strength for mainline?


When you choose your line, the main question you need to answer is: where am I going to be fishing?


Answering these questions properly requires the answers to so many other questions about the fishing situation that it’s no wonder anglers struggle with the subject. For me, it comes down to this:

  • It doesn’t matter whether you are fishing in the UK or abroad because what really matters is the nature of the lake: fishing large snag free lakes is completely different to fishing small snaggy estate lakes for example.
  • There is no such thing as the perfect mainline. Every fishing situation is different and what suits one angler or lake may not suit another. The perfect mainline is always a compromise of various parameters.

The good news is that certain lines seem to be able to balance out these factors and perform across a wide range of angling situations and if you can find one of these, then it’s one less thing to worry about. I give you my personal favourites in the second part of this article.

What do you need your line to do?

When you look at mainline in more detail, we actually expect it to perform in a number of areas. The problem is that excellence in one area usually comes with compromise in another. From an angling perspective, I’m going to break down mainline performance into the following categories:

  • Abrasion resistance
  • Knot strength
  • Ability to sink
  • Ability to cast
  • Elasticity
  • Colour
1. Abrasion resistance

how to test the strength of your mainline

In an ideal world, there should be an international line testing body offering a universally acceptable test that manufacturers could submit samples to to enable the relative abrasion resistance of lines to be measured.

A major oversight as far as I’m concerned because this does not exist!

What we actually have amounts to nothing more than the claims of manufacturers and hearsay as to whose line is the toughest! The only piece of actual data that can be used for comparison is that of line diameter.

Yes you’ve guessed it, thicker is better.

But apart from that amazing insight all we can really do on this front is buy some and test it ourselves. I know it’s not ideal but it’s easy to do and, with the right approach, might not even cost you anything.

Here’s how you can easily test your line: 

Just grab a length of line with both hands and rub it over rocks or branches, anything that’s to hand really that you know exists under the surface of the lake or river that you’re fishing. You’ll soon get an idea of how tough it really is! Once you’ve abused it sufficiently in a variety of ways, you can make your own decision as to whether it’s up to the job or not.

If you’re not happy, take it back.

It’s far better to reject something straight away than to spool up and hope! When choosing mainline for abrasion resistance ignore the stated breaking strain and concentrate on the diameter. I use 0.40mm for most of my work. In extreme situations such as river carp fishing, I add 10m of heavy braided snag leader.

2. Line strength ... well it's about knot strength really

how to test the knot strength of your mainline

I can honestly say that I’ve never read any blurb that does not claim “high knot strength” to be a property of the line in question.

Ah, if only this were true!

The main point here is that the stated breaking strain and the actual breaking strain of various lines are different.

Actual line strength is limited by knot strength and this is what you need to worry about.

Fortunately, help is at hand on this one from those talented boys at the Tackle Box in Kent. Check out their line test data here.

This is an awesome guide that measures and compares stated diameter and stated breaking strain (using real carp fishing knots connected to actual hooks and swivels) for every single make of line that’s used for carp fishing. The testing has been done using rigorous scientific methods and it’s a real eye opener when you start to compare products. For example, one 15lb mono on the chart actually broke at just over 10lbs! When fishing for carp of any size in any lake I would want to choose line strength of 15lbs minimum as per this chart and if casting distance is less of an issue, go for 20lb line.

A careful study of this could save you a lot of time, money and lost carp.

Many UK and French fisheries state a minimum breaking strain of line to be used. This number is usually 15lbs. We now know that some 12lb actually breaks at 15lb+ but whether this is suitable for the venue in question or not is a question that should be directed towards the fishery manager.

At Beausoleil, I state a minimum line diameter of 0.40mm to be used due to the level of underwater hazards (such as branches, roots, and rocks) at the venue. It’s not that the venue is snag ridden, it’s fairly clean in fact but it’s a tree lined lake and branches fall in.

3. Ability to sink


In scientific terms, it is about the gravity of the line material. If a material has a specific gravity of 1.0, it means that the line will be of neutral buoyancy.

  • The specific gravity of nylon, which is mainly what mono filament mainline is made from, is 1.12. In other words it sinks… just!
  • Fluorocarbon is much higher at between 1.75 and 1.90 so it sinks like a brick.
  • Braided mainline is available in both sinking and floating densities and has many applications.

Although mainline that sinks is generally thought of as good, in my experience, it can actually expose the mainline to more hazards than standard mono. Nylon actually absorbs water and becomes heavier over time as do most braids. Fluorocarbons do not absorb water and their specific gravity remains constant. Unfortunately very few companies will actually tell what you what the specific gravity of their product is.

The other factor which affects sinkability is that of line cleanliness.

To put it simply: dirty line sinks poorly, clean line sinks well.

Cleaning your line is easy to do. Just cast out and wind back through a damp cloth or dedicated line wipe. It should be a routine part of your carp fishing. Personally I like a mainline that sinks readily but doesn’t bury itself unnecessarily in god knows what.

4. Ability to cast

angler casting in estate lake at french carp lake

Here’s a classic line: “Casts very well”.


When what it should say is: “Casts like a bag of spanners!”.

Again, the only real piece of data that can be used to judge how well a line is going to cast is that of diameter.

I use 0.34mm mono when fishing at range in open water that is free from snags.

Other factors that affect castability are memory and suppleness. Both of these are subjective words that the line manufacturers use and abuse very frequently. Personally I’d ignore such statements and just choose a low diameter line of between 0.28 and 0.34mm. Once you go below 0.34m in mono you’ll need to add a leader of some sort to absorb the force of the cast.

No matter what anyone tells you, fluorocarbon lines do not cast well!

Low diameter floating braids cast the furthest but are prone to wind knots which can be a real pain.

5. Elasticity of your line
  • You may not have ever given much consideration to this but mono has a massive amount of stretch in it. In many situations this is good because the line absorbs powerful lunges from big carp. It also helps to land a rig neatly on the surface in a tangle free fashion when fishing clipped up.
  • The farther out you fish the more stretch there is and I’d say at ranges in excess of 150 yards, braid is the only way to go.
  • Fluorocarbons have less stretch than mono.
  • For fishing at any range close to snags braid is seriously worth considering. If you’ve got the bottle and the gear to hit and hold that is!

When fishing close to snags with mono, my rule is to fish at least 5m short. This also depends on the range I’m fishing at. The 5m is made up of 1m to get an indication and take up the slack in the line, 2m – 3m of elasticity when the line is taught and the rod is hooped over and the rest is a theoretical safety margin. When using mono, if you’re fishing less than 5m away from under water obstacles you are taking a big risk with the safety of the fish, and that for me is unacceptable.

6. Line colour

Thanks to the line companies and the many underwater DVDs, rig camouflage has been the in thing in carp fishing for some years now. I’ve watched them all and enjoyed them but you’ve got to take all the commentary with a large pinch of salt. For me, matching the colour of various lines and rig components to that of the environment in which you’re fishing is total nonsense and makes no difference whatsoever to your results.

This may come as shock but it’s true.

When choosing a main line, I don’t mind whether it’s clear, brown or green no matter where I’m fishing.

What I make sure is that it’s on the bottom, close to the rig. There, the carp can’t see it or hopefully feel it.

In a perfect world, the best carp fishing mainline would have awesome abrasion resistance, sink like a brick, cast 200 yards and knots would be 200% as strong as the material itself, oh and it should be totally tangle proof.

Funnily enough this is not the case!


This is a topic that we can debate forever …. feel free to join the discussion or leave a comment below.

Tight Lines.

Fancy a fishing holiday at Beausoleil Carp and Cats?

Find out More

You may also like...

Leave a Reply

Your email address will not be published. Required fields are marked *