Mainline
Mainline — The line on the reel spool, from the reel to the rig. It is the cheapest metre on the water because one spool feeds hundreds of casts, and its job is to stay thin enough to cut a swim and strong enough to land a fish without ever being the part that breaks on a snag.
Hooklength
Hooklength — The short, replaceable section between the feeder and the hook. Its length and its diameter are the two variables a feeder angler retunes during a session, so the hooklength is where a rig stops being equipment and becomes a setting.
| Depth and flow of the swim | decides feeder weight first |
|---|---|
| Distance bait must sit from the feeder | decides hooklength length |
| How tightly the fish feed | decides hooklength diameter and hook size |
| Casting frequency and bottom cover | decides mainline diameter and wear limits |
| Largest fish possible in the venue | decides reel drag and mainline breaking strain |
The mainline is a cost, not a component
The mainline carries a contradiction: it is the most important line on the water and the cheapest per metre, because a spool feeds a whole season of sessions. That is why the classic mistake is either extreme. A line too thick for the venue shows the fish a cable between the feeder and everything they investigate, and it saws through weed and surface chop you cannot see; a line too thin dies on the first crayfish or the first wind-blown snag, and losing a fish is not free either. The sane answer is the strongest thin line your budget allows you to re-spool the moment it feels rough, and to check it with your fingertips every few casts, because abrasion shows as drag before it shows as weakness.
The feeder holds bottom; the fish decide nothing about it
Weight is where beginners overreach, so say the rule plainly: pick the lightest feeder that still rests on the bottom with the line bow trimmed. A feeder that drags or lifts tells you the river is heavier than your tackle thinks, and the answer is the next weight up, not a tighter bow. Inline feeders put the bait at the mouth of the cage where the groundbait is already falling, which suits fast, confident feeding; open-end and cage styles suit longer hooklengths and warier fish that will not come inside the cloud. None of these is the best feeder — they answer different questions the swim asks.
The hooklength is the setting you retune
Between the feeder and the hook you control the last metres, and bites read the hooklength even when you do not. A longer hooklength lets the bait drift away from the feeder and hangs past a wary carp’s suspicion of the cage; a shorter one puts the hook back in the feed and fires a better hook-up rate on confident fish. Drop to a finer diameter when the fish pull the tip over and then let it come back, which is a pick, not a knock; stay stronger when there is a big fish in the venue and weed between it and the net, because the landing phase is where fine lines actually die. Tie or buy spares in pairs of diameters, and change the length at the same time as the diameter — if you change two things at once you learn the rig faster and the water faster, in that order.
Why does a heavier feeder not catch bigger fish?
Because the feeder's weight is chosen by the water, not by the fish. Its only job is to hold bottom so the rig stays where you put it, and once it holds, extra weight adds nothing except a harder cast, a louder splash and more lead carried home. On still water a light feeder that holds is the right feeder; a river that lifts the line will demand several times that weight, and that is the whole logic of the size ladder.
Which part of the rig should I expect to replace most often?
The hooklength, and for two different reasons. Mechanically it is the shortest line and the one tied into knots and a hook eye, so it weakens fastest; tactically it is also the part you change on purpose when bites go from confident to pricked. Mainline, feeder and reel are chosen for a season of venues; the hooklength is chosen for a swim and re-chosen at lunchtime.