Pole Line Diameter


Regular member
Aug 24, 2010
I'm going to apologise in advance, as I'm sure this topic is a frequent flyer.

I'm interested to know if anyone fishes with differing mainline diameters on commercials, depending on species targeted or time of year, and has possibly actively compared to see if a thinner mainline does make any difference at all, or if everything revolves around the hooklength.

Ive seen plenty of anglers - far better than me, State the main line diameter still doesn't matter.

My issue probably stems from my background in fishing on natural venues, where you were scratching for bites. The water was clear and when fishing became more focused on diameter of line rather than BS, it made sense to use a thin and supple main line.

Fast forward 25 + years and I still struggle to get out of that mindset.

Over the years, I've gradually weaned myself of thinner lines and gone heavier, but I still struggle mentally with accepted that 2-4 inches of a thinner hooklength will keep the bites coming without also dropping down the main line. If so, why do we bother to fine down in winter at all? Surely hooklength is all that matters, whatever the time of year.

If I fished more often, in guessing I could easily compare results on the day, but with my limited time on the bank I don't see that as an option.

I've settled on having Margin rigs on 0.20-0.18 line, and summer open water rigs on 0.16, but I've still found myself making up a host of 0.14 rigs for commercial Silvers, with 0.13 for winter.

Along with the angling sage that is Neil Of The Nene, I too don't like a mainline that is more than 0.03 thicker than my hooklength. Whether this has any scientific basis, or just feels right/wrong I couldn't say,but probably shapes my thinking a bit more.

(Bear in mind this is purely about commercials - do I need to remove the last safety blanket and man up (as it were) and ditch the lighter rrigs)

Has anyone ever actively compared if main line diameter makes the blindest (pardon the pun) bit of difference for the same hooklength diameter?

Should I just wack everything in 0.18 and stop obsessing and pussying around?

Comments appreciated and can if worms opened no doubt 😊
Last edited:


Staff member
Site Supporter
Aug 22, 2006
No can of worms, it depends what you are fishing for and when. In the summer you’ll often catch silvers on carp rigs, commercial fish are still fish and react to their needs and instincts, hungry they’ll be competing for food and line dia will become insignificant to an extent. Not hungry or clear water in the winter, then yes, fining down will get you more bites. I fish an 0.10 hooklength in the winter for silvers, but carry 0.08 tied hooks and won’t hesitate to drop down if I think it will get me more bites. I’d also expect to land most carp on 0.10 in the winter, but wouldn’t target them using it. That would be 0.11 or 0.13.

Bear in mind I only match fish, so the fish are always more pressured than when pleasure fishing, maybe pleasure fishing you could fish heavier, but getting the rig and hooklength right would still put you more fish in the net, although as ever, the most important thing is feeding.

Neil ofthe nene

Doing things differently.
Site Supporter
May 4, 2009
Like Maesknoll I fine down in the Winter to a 0.10 hooklength and 0.13 mainline. Summer that will be 0.17 main and hooklengths of 0.13 & 0.17. The hook sizes change with the seasons also. I don't like a huge step between main and hooklength.

The thing to remember is that most of the time a mouth hooked fish cannot swim away from you with a power that exceeds or even matches their weight. Hence you can land fish that are heavier than the stated BS of your lines. You can't bully them and you can't lift them from the water, but you can land them.