The bob fly is pulled toward the boat with a fish tucked in behind it; a soft boil erupts just behind the fly with no burst, and only at the hang does a quiet ring confirm the take — never strike the swirl itself.
The swirl behind your flies is a fish deciding, not a fish hooked. Keep the retrieve, slow into the hang, and strike only when the line draws heavy.
On the lough
The boil behind your fly
A boil behind a pulled fly is a following fish making up its mind — strike the boil and you take the fly off it.
You'll see
You're pulling a team from the boat and the water humps or swirls behind the flies — once, sometimes twice — with no weight in the line. Maybe a flash of gold under the bob fly.
What it means
A fish has followed and turned at the fly — interested, not committed. How a brown trout takes a moving fly is down-turn-away: the boil you see is often the turn BEFORE the mouth closes. Interference now loses the fish; the right move keeps it coming.
The flies to answer with
How to fish it
Keep the flies coming
Same pace, same line. The follow is live until you change something. Rod tip up — around 45° — so there's a cushion between you and the fish.
Give it the dibble
As the team nears the boat, slow and lift so the bob fly furrows the top — the hang. A following fish that wouldn't take at speed very often takes the dibbled fly or the hung dropper.
Let it turn
When the take comes, the line draws — weight, not splash. A touch of controlled slack helps the fish turn down without feeling you; a locked-tight line bounces fish off.
When to strike
Wait — say LoughLogic twice
Never strike the boil — strike the draw. It's the same discipline as the dry: confirm the fish has it ("LoughLogic, LoughLogic"), feel the weight, then pull into it. On a tight-ish line the fish half-hooks itself on the turn.
The strike clock →Easily misread
Striking the swirl
You see the boil, whip the rod up, and the team flies out of the water — fish gone, often for the drift.
Instead: The boil is a question, not a take. Answer it with the dibble and the hang, and strike only weight.
"It refused — change the flies"
One boil, no take, and the whole cast gets rebuilt.
Instead: A boiling fish is a positive fish. Cover it again first — same team, slightly slower, dibble longer. Change flies only after it's seen the hang twice.
When you'll see it
- Pulling wets from a drifting boat in a wave — the bread-and-butter lough day
- Fish coming 'short' in bright or flat conditions
- Behind the bob fly on the lift, just before the hang
Related
Sources & how we know this (2)
- Don't strike the boil; keep the rod up, give the fish rope, strike when the line draws tight — the down-turn take mechanics
Alex Baker (LoughLogic), firsthand — loch-style lore he confirmed on his authority 2026-07-16 (consistent across loch-style literature; no single clean citation) · 2026-07-16 - The hang/dibble converts followers: induce with the lifted, dibbled bob fly rather than holding flies dead still
Trout and Salmon — The essential guide to retrieving flies from a boat on stillwaters · 2026-07-16