Is there a simple equation for lure depth given how much line is out for trolling behind a canoe? I thought I read somewhere that it’s approximately 6 feet of depth for every 10 ft of line or something like that. I’m targeting lake trout in mid summer so hoping to get at least 30 ft deep with crank baits and spoons.

It varies greatly depending on the angle and size of the lip on the crankbait — and other factors such as the diameter of your line and the boat speed matter as well. That said those numbers you suggested seem way conservative.

To hit that 30 foot mark without adding weights, you are going to want the largest size Rapala Tail Dancer or something similar, and you will need to put somewhere around 150 feet of line out.

You can google “dive curve” for a particular bait and sometimes find a chart that shows. There is also an app called Precision Trolling that allows you to manipulate all the factors to get pretty, well… precise. But it’s expensive and overkill in my opinion.

What Gilded said. Get the biggest Taildancer in purpledescent. Braided line, and about 150 of line out, you're looking at 30 feet down. I've marked 150' (and other lengths) with a bobber stop; works good.
150' of line with a small spoon will get you down 5 feet. A #7 shad rap will be 12-ish feet down. So it depends on all sorts of things.

Got any particular crankbaits you want the dive curves for? I have an old precision trolling book and can look up the curves for you.

I like to use snap weights for those situations where I want to get deeper than the bait otherwise allows. For example trolling sutton spoons.

I use the Precision Trolling App and find it really useful.

As you can see from the charts using a Rapala TD-11 TAILDANCER you will be 32 feet down with 150 ft of line out with 10 lb Fireline Braid.

You will need to let out 182 feet of line to get down to a maximum 29 ft deep with 10 lb. Berkley XT Mono line.

And remember those depths are with a properly tuned crankbait.

There's always this method which works for me.

1. Let out a lot of line and start trolling your crankbait
2. Accidentally run too shallow and note the depth of where the crankbait starts dragging rocks. Now you know the depth it's running.
3. Go deeper again and keep trolling.
4. Accidentally run too shallow again and get hung up.
5. Break your line trying to free said crankbait.
6. Curse and swear before tying on a new crankbait.
7. See step #1.

;)

DTrain: "There's always this method which works for me.


1. Let out a lot of line and start trolling your crankbait
2. Accidentally run too shallow and note the depth of where the crankbait starts dragging rocks. Now you know the depth it's running.
3. Go deeper again and keep trolling.
4. Accidentally run too shallow again and get hung up.
5. Break your line trying to free said crankbait.
6. Curse and swear before tying on a new crankbait.
7. See step #1.


;)"

Hahhahahahhaaaha! Thanks for the laugh! I needed that.

scottiebaldwin: "

DTrain: "There's always this method which works for me.

1. Let out a lot of line and start trolling your crankbait
2. Accidentally run too shallow and note the depth of where the crankbait starts dragging rocks. Now you know the depth it's running.
3. Go deeper again and keep trolling.
4. Accidentally run too shallow again and get hung up.
5. Break your line trying to free said crankbait.
6. Curse and swear before tying on a new crankbait.
7. See step #1.

;)"

Hahhahahahhaaaha! Thanks for the laugh! I needed that. "

This hits a little to close to home...

That's MY preferred method as well!

DTrain: "There's always this method which works for me.


1. Let out a lot of line and start trolling your crankbait
2. Accidentally run too shallow and note the depth of where the crankbait starts dragging rocks. Now you know the depth it's running.
3. Go deeper again and keep trolling.
4. Accidentally run too shallow again and get hung up.
5. Break your line trying to free said crankbait.
6. Curse and swear before tying on a new crankbait.
7. See step #1.


;)"

My method exactly! I can't say it's less effective then the more technical ways to go but it is definitely more expensive.