For trollers · Great Lakes, lakes, rivers and the coast
TrollingHelper works out how deep each lure runs from your line, weight, diver, leader and lure at your real speed through the water, then tells you how much line to let out to reach the depth on your sounder. For every rod in the spread.
Try it
This is TrollingHelper's depth model running in your browser, the same one the app runs on your phone. Pick a rig or build your own, turn the dials, and watch the line settle under the boat. Add a knot of current and see how far the same lure moves between heading into it and running with it.
The app adds live GPS speed, takes the current out for you, keeps your whole spread and learns your tackle when you calibrate it.
Set it on deck
Line out, weight, speed, cable and ball are big dials you drag around, with − and + buttons underneath that keep going while you hold them. No tiny text boxes, no keyboard. Change anything and the depth and the line's shape under the boat update as you go.
Speed through the water
Lures run on the speed of the water past them, not your speed over the bottom. Troll 2.5 on the GPS with a knot of current behind you and the lures only feel 1.5: they sink. Turn into it and they feel 3.5 and climb. TrollingHelper reads your GPS speed and course and takes the current out. On covered salt water it knows the tidal current from NOAA stations; on lakes and rivers you set it, or use your speed probe. Then it shows how deep the same rig runs into the current and with it.
The whole spread
Set up each rod once, divers, copper, leadcore, snap weights and riggers, and the spread shows where every lure is at today's speed. Change speed and they all move together, so you can see which lines will tick bottom on the turn before they do. Rods stay saved for the next trip.
Get to a depth
Put in the depth you're marking and TrollingHelper works backward to the line out, or the cable for a rigger, and sets it with one tap. The dive chart lays out 50 to 300 feet back at your speed, so you can stagger the spread through the column and move lines to the depth that's getting bit.
Your tackle
Mono, braid, fluoro, leadcore by the color, copper and wire. Sinkers, snap weights at any split, disk divers with the dial setting, No. 1 to 3 planers and downriggers. Crankbaits by how deep they're built to dive, spoons, harnesses, flasher and fly, bucktails, parachutes and umbrella rigs. Set the real weight of your lure. Any combination gives an answer, never "no results".
How it works
Most depth charts were measured for one line at one speed. TrollingHelper solves the line itself, a few inches at a time from the lure back up to the rod tip, so it can answer for the rig you're actually running.
Water pushing across the line lifts it and lays it back. More speed, more line or thicker line all flatten the curve. Braid cuts through it; heavy mono planes up.
Sinkers, leadcore, copper and wire sink in the water; disk divers and planers dive. The lure hangs off the end with its own weight and drag.
A tall rod tip on a long, flat line can hold a lot of line above the water. The app counts it.
Current behind you lets the lures sink; current in your face lifts them. The app takes it out of your GPS speed.
Tackle varies. Check a rod once with a depth logger, or troll until it ticks bottom at a known depth, and that rod follows your gear from then on.
The numbers start from common rules of thumb (leadcore about 5 ft a color, copper about 20 ft per 100) and get better when you calibrate.
Where it works
Fresh or salt, still water or current. Pick the water and the rigs you run there.
Salmon, trout, walleye
Disk divers on braid or wire, copper and leadcore off boards, riggers down the column. Fresh-water density is built in.
Walleye, stripers, crappie, bass
Crankbaits by dive class, snap weights at any split, harnesses and spoons on mono or braid.
Current that never stops
Set the current and which way it runs, and the app shows the difference between pulling up and dropping down.
Chesapeake, Charleston and more to come
Bucktails, umbrella rigs and planers, with the tidal current from NOAA stations taken out for you.
Every depth is worked out on your phone in a fraction of a second, and the tidal currents are calculated from NOAA constants on the phone too. No signal ten miles out, no problem. No account to make, and your rods and settings stay on your phone.
Pricing
The free version answers the question for a sinker or snap-weight rig at any speed. Pro adds live speed, the current, every rig and the whole spread.
$0
No ads. No account. Works offline.
$19.99 / year
Or $49.99 once for lifetime. Try the yearly plan free for 2 weeks first.
Everything in Free, plus:
Pro yearly is an auto-renewing subscription through the App Store; the 2-week free trial is for new subscribers, and you won't be charged if you cancel before it ends, in Settings › Apple ID › Subscriptions. Lifetime is a one-time purchase with no renewals and restores on a new phone. Available on the US App Store.
What's next
Mark a fish and the app saves which rod, lure, depth, speed and current it came on.
Each rod's depth against line out as a curve, side by side, to compare rigs at a glance.
Popular crankbaits and spoons with their own numbers, from our own depth-logger runs.
NOAA current stations for more coasts, so the tide's current comes out on its own in more places.