Fishing from a boat, whatever its size: rigging the boat for it, holding position on a mark by anchor or by trolling motor, and the electronics that find the fish and bring you back to the same spot.
Motor up-current or upwind of the mark by two to three times the water depth, so that in 10 m of water you stop 20–30 m short of the spot. Lower the anchor to the bottom, pay out rode as the boat drifts back, then snub the line so the anchor digs in. Pay out a little more and the boat walks back until it sits just up-current of the structure, with your bait drifting down onto it. If you overshoot, shorten up; if you fall short, pay out more. The anchor holds the bait on the fish, not the boat on a picture.
What scope should you use when anchoring for fishing?
Three to five times the depth, measured from the bow roller to the bottom. That is shorter than the 5:1 to 7:1 used for overnight anchoring, and it is deliberate: a short rode makes the boat swing less and lets you adjust position by paying out or hauling in a few metres at a time. In current the anchor needs enough angle to hold, so start at 3:1 in calm water and go to 5:1 or more when it blows, when the current runs hard, or when the anchor keeps skipping over the bottom.
What is the best anchor for a fishing boat?
It depends on the bottom, not the boat. A grapnel or reef anchor with bendable tines is the choice for rock, wreck and coral, because the tines straighten under a hard pull and the anchor comes back. A Danforth or other fluke anchor holds best in sand and mud and folds flat in a small boat. Many small-boat anglers carry both, plus a length of chain and a float. A single folding grapnel is only for a kayak or a lake with no wind; it holds almost nothing in soft ground.