What makes trolling different?
Trolling is active fishing from a boat: you pull lures behind you at a steady speed while the boat covers a large area. You search for the fish instead of waiting for them. That differs from casting in two important ways:
- The speed is constant. The boat's speed decides how the lure swims — too slow and the crankbait goes dead, too fast and the fish cannot catch it. The window is usually 2–4 knots.
- The depth is planned. With several rods you can cover different depths at the same time, and that is trolling's great advantage over casting.
The technique suits the large Swedish lakes (Vänern, Vättern, Mälaren, Hjälmaren, Storsjön) and some coastal areas, where the fish spread over water you cannot reach from land.
What you need to start
You can start trolling without buying a specially equipped boat. The minimum:
- A boat with a motor that will hold a steady low speed. A 5 hp outboard is often too strong to run slowly enough; an electric motor or a trolling plate solves it.
- A sounder. Not optional in the longer run — you want to see where the fish are and which depths are worth working. A simple sounder is enough for a lot of fishing; side-scan and structure scan are luxury.
- Two spinning rods rated 30–80 g with multiplier reels or larger fixed-spool reels. Buy reels with a line counter so you know exactly how much line is out.
- Diving crankbaits — pick two with different diving depths (1–3 m and 4–6 m) so you cover both the shallow and the deeper layer.
- Safety equipment — a buoyancy aid for everyone on board, a line and a bailer. See boat safety and water safety.
Once you know it is for you, a downrigger and planer boards are the two investments that make new things possible: the first puts the lure at an exact depth, the second spreads several rods out to the sides.
Speed, depth and line length
Three things decide the catch — and all three are under your control.
Speed: pike generally take better at 2.5–4 knots and zander at 2–3. Salmon and trout in the great lakes sit in the same window. Too slow and the lure stops wobbling; too fast and the fish cannot attack it. The GPS gives you true speed over ground; the paddle-wheel log does not always.
Depth: a crankbait marked "dives to 4 m" does so at a typical line length (often 30–50 m out). More line means deeper; thinner line means deeper. Use the counter on the reel so you can repeat the same depth.
Line length: in quieter water, 25–40 m out is enough. Over clear shallows where the fish are shy it can take 50–80 m. More line means more fish when they are wary of the boat.
Reading the sounder
After the boat itself, the sounder is trolling's most important tool. Three things to learn to read:
- The bottom contour. Sharp edges, where the bottom falls from 4 to 12 m over a short distance, are hotspots — prey fish gather there and predators wait below.
- Shoals of prey fish. They show as clouds or bands on the screen. The predators often sit just below or beside the shoal.
- Single fish marks. Big fish show as thick, isolated marks — often those are the fish you are looking for.
Log GPS positions when you catch a fish or see an interesting structure. Much of the success in trolling comes from returning to places where the fish were, and a memory in the form of map data is worth a great deal.
Common beginner mistakes
- Too much speed. The commonest error. Drop to 2.5 knots and see what happens.
- Too few rods out, too few depths tested. Two rods at the same depth give you one data point. Two rods at different depths give you two. Four rods at four depths give you what trolling is actually for.
- Worn lures. Crankbaits lose their shape after a season; check that they swim straight alongside the boat before you let them out.
- No wire trace when trolling for pike. Sharp teeth cut monofilament in seconds. Always use steel or titanium for pike.
- Not writing anything down. An hour after a good trip you have forgotten which speed, which lure, which depth. Write it down — or log the catch on Fångstrapport straight away. The spot does not travel with it: other people see which water it was, never where in the water. Your exact position is kept in your own logbook, where it is of use to you.
A first trip — how to plan it
Three or four hours on familiar water is enough for a successful first trip. One way to lay it out:
1. Before the trip: read the depth map and the chart. Mark 3–5 interesting structures (edges, underwater shoals, river mouths). 2. At the launch: check that the lures swim straight alongside the boat at low speed. 3. The first pass: follow a bottom edge at 6–10 m at 2.5 knots. Two rods out, one deeper and one shallower. 4. Adjust: change depth if nothing happens in 30 minutes. Drop the speed by half a knot. Change colour. 5. When you catch a fish: mark the position on the GPS and turn the boat back for another pass over the same spot.
And: trolling is not always action. Even a trip without a fish teaches you something — the depth map got more detailed, a spot could be ruled out, a combination was tested.