Figuring out depth of lure without downrigger

I used to always have this debate while trolling for lake trout on our Canadian wilderness canoe trips.

How deep do you think you get trolling a spoon behind 2 oz of weight?  How about 3 oz of weight?

There are obviously a lot of variables (diameter of line, speed, amount of line out, etc), but let's assume some typical specs here. 10 pound line, typical lazy paddling/trolling speed that makes the spoon flutter, and a fair amount of line behind you.

I wonder because I now troll out of a yak with a fish finder but no downrigger, so it becomes a bit of calibrating how deep I think I am with the school of fish on the finder.

My second question...do you think pulling a crankbait (wiggle wart type bait or other wobbler) behind a couple ounces of weight kills the action on the plug?  Is it a no-no? I've always wondered about that. I've caught plenty of lake trout in Canada pulling Shad Raps behind weight, but some of those fish seem like they'd hit a beer can.

Just curious.

With some trig and calculus you can figure it out. Just need the angle the line enters the water, the amount of line out, and a guess on the arc of the parabola that the line forms.  Ugh.    I've seen a few charts online that try to outline it, but I don't trust them.  I guesstimate.

As for your plugs, the bigger the "swing" of the bait, the more leader you need between weight and lure.  Test shallow alongside the boat with a long leader and see where performance falls off.  I use the longest leader that will allow me to still land the fish.

Thanks 'Yak. But what's your guess on 2 oz of weight? 25 feet maybe?

How long a leader are you talking about for a wobbling crankbait?  7 feet?

There are multiple factors that will affect your trolling depth, including line diameter, trolling speed, current, weight you are using, drag of lure/bait, etc. Simple trigonometry on the angle or your line entering the water would be deceiving given that the line flattens out underwater the more line you put out there. Depending on the type of fishing you are doing (target species, depths, dishing setup), and barring the use of downriggers, you could look at using planers or divers. There are several charts online that will give you some idea of how much line out you need for different depths, here's one of them: http://www.straitlineanglers.com/Articles/Depth_Chart_For_Diving_Planers.htm
Don't trust those charts too much, as you'll probably be fishing with a setup different that what they report. A simple way to create your own chart is to troll your setup (minus hook to minimize snags) in areas of different know depths at typical trolling speed and take note of how much line out (count the pulls, mark your line or use a line counter reel) you need until you hit bottom. I use a Deep Six (#2 or double 2) with braided line of 15 lbs or 20lbs, comparable to a 4 lbs monofilament line diameter. With the double six setup I get down to 80 ft with 125 ft of line out fishing for sockeye. Fishing at faster speeds (say for coho or kings) your line would be closer to the surface, but you can test it with the method I mentioned earlier. Good luck!

It's pretty much a guess IMO. There's sooo many variables to choose from. And if you're in a body of water that has current it's even harder to pin down. I usually use pulls off the reel as a estimation of depth. If the line angle is near 45º I'm in the ballpark and fishing.

So 2-3 oz. of weight? Depends on how fast you're going, how much drag your lure/bait is producing, and what type of line you're using. Mooching a cut plug herring, w/ 25# mono, w/ 4 oz. @ 1.5mph I've gotten down 180' plus. At a speed around 2mph I think 3 oz. might get you to in the 50'-70' range.

And pulling a crankbait behind a sliding sinker not only doesn't kill the action but is really effective. There's lots of people who use that method for many different types of fish.

Z

Thanks guys. Zee, that's about what I was thinking on the depth with 3 oz. You mention sliding sinkers...what about pegged in-line trolling weights, with a leader of 6 feet or so? Wobble fine?

mention sliding sinkers...what about pegged in-line trolling weights, with a leader of 6 feet or so? Wobble fine?

Yep. I think its shimmy will be doing just fine.

Z