Trolling Depth Estimation

Hey  Alaska Yak Crew.

So I was trolling around Homer a few weekends back from my OK prowler 13. I trolled pretty consistently  for 3 hrs only the occasional break to freshen my herring. I had a speedometer on a phone app and as we'll as Lowrance. I varied my speed between 1.5-3mph. I did end up three take downs: 1 landed pollack, 1 lost king, and a 3rd fish I never got a hook into. But the whole time I had no idea what depth I was trolling at. I have a line counter with color coded line, so length of line out is easy to figure out. I'm sure I could use some trig (length of line times the sine of the angle formed between my line and water surface) to figure it out, but seems like to much work. I use banana weights (2-10 oz) and want to try them until they fail before switching to diver or downrigger. Does someone have a rule of thumb or trick for figuring out trolling depth when trolling w/ weights?

Thanks AKStumpy

Here is the best graph I have found so far.   Leeroys ramblings has alot of good info.

Interesting, as a general guideline, but doesn't take into account line weight or speed as well as others.

You will get a feel for your depth after you drag the bottom a few times. 

I own a product called the Fish Hawk which you clip to your line. It measures depth and temperature in 5 foot increments http://www.fishhawkelectronics.com/marine-electronics/fish-hawk-td.html .  Great for lead core line users.

I like downrigger trolling because it allows me to precisely control the depth of my lure, and it allows me to respond rapidly to changes in the depth of the bottom and the location of fish in the water column.  For example, if I'm trolling for kokanee with my weight and lure at 30 feet, and I encounter a school of kokanee at 45 feet, I can quickly drop my weight so my flasher and lure will run through the school, and can hope to get a hit on the first pass, without making repeat passes through the school in a cloverleaf pattern with the help of GPS. Or if I'm fishing for lake trout which are hanging out on a mound in the bottom, I can fly my weight up one side of the mound and down the other, just a few feet above the bottom all the way.  Because I do a lot of downrigger trolling, trolling with leaded line, sinkers, or divers usually feels unacceptably unpredictable, uncontrollable, and random.

Here is the best graph I have found so far.   Leeroys ramblings has alot of good info.

That is a handy chart. Nice find.

I own a product called the Fish Hawk which you clip to your line. It measures depth and temperature in 5 foot increments http://www.fishhawkelectronics.com/marine-electronics/fish-hawk-td.html .  Great for lead core line users.

Cool!

I troll with banana weights and DeepSix almost exclusively.  Current has a huge effect on how deep you are, as does speed of trolling obviously.  You don't need to do trig - just look at your angle and get to know how deep you are getting by correlating info from your FF, bumps on bottom...etc.  After years of fishing this way I am confident of where my gear is a high percentage of the time.

Trig won't work anyway - your line 'balloons' out a bit due to drag, so it's all about getting a feel for it.

I troll with banana weights and DeepSix almost exclusively.  Current has a huge effect on how deep you are, as does speed of trolling obviously.  You don't need to do trig - just look at your angle and get to know how deep you are getting by correlating info from your FF, bumps on bottom...etc.  After years of fishing this way I am confident of where my gear is a high percentage of the time.

Trig won't work anyway - your line 'balloons' out a bit due to drag, so it's all about getting a feel for it.

You also need to get the feel for where your weight and lure are when downrigger trolling.  Because a downrigger weight blows back, if your fish finder shows the bottom at 80 feet and your weight at 75 feet, depending on how your fish finder works, the weight may actually be more than five feet above the bottom.  The amount that a downrigger weight blows back depends on your speed, the size of the weight, the depth at which you are trolling, and the drag of your weight, cable, and lure; for example, a Flatfish or Kwickfish lure has much more drag than a typical Rapalla-style lure, and will pull your weight back more.  When moving in a straight line at a steady speed, some lures run only a short distance below your downrigger weight, while other lures run quite a bit below the weight.  When you slow up your kayak or turn (which causes your lure to slow up), a floating lure will tend to float up, but a sinking lure will tend to sink. These factors aren't very obvious when you're trolling in the middle of the water column.  But if you're trolling right above the bottom, you can pretty quickly figure out the relationship between where your weight appears on your fish finder and how much actual clearance there is between your weight, your lure, and the bottom, by dropping your weight until your weight or your lure clips the bottom.

Nevertheless, the advantage of a downrigger is that the weight hangs only a short distance behind your kayak, and allows you to quickly and accurately change the depth at which your lure is running.  Plus when you catch a fish, you pop your fishing line out of the downrigger release, and can play the fish without any interference from the downrigger weight.

He's not asking about downrigging.

I troll with banana weights and DeepSix almost exclusively.  Current has a huge effect on how deep you are, as does speed of trolling obviously.  You don't need to do trig - just look at your angle and get to know how deep you are getting by correlating info from your FF, bumps on bottom...etc.  After years of fishing this way I am confident of where my gear is a high percentage of the time.

Trig won't work anyway - your line 'balloons' out a bit due to drag, so it's all about getting a feel for it.

This is why you need to do calculus while on the water.  Usually it's just a double integral, and it's solved from zero= water surface, to frustration= infinity.  :-)

He's not asking about downrigging.

AKStumpy said "I use banana weights (2-10 oz) and want to try them until they fail before switching to diver or downrigger. Does someone have a rule of thumb or trick for figuring out trolling depth when trolling w/ weights?"  What I say is that while sinker rigs have their uses, downriggers are better.  So dump the sinker rigs and get a downrigger.

I'm a fan of heavy banana sinkers up to 16oz. I use the 12oz a lot. The only exception is in May when kings are shallow. The line control is much better and the math much easier with less line out.

Even the sinkers for me, I use only down to about 20 to 25 ft.

Down to about 40ft I'll use a deep six. 

For much of the saltwater I fish there is no thermocline or structure. Precise depth control is rarely necessary.  Salmon will move (up more than down) 10 or 20 ft or more to hit a bait.

For me, downrigger shines in winter when fishing deep and for getting lighter gear down where it'd be weird to use heavy weights.

In Southcentral Alaska saltwater a downrigger is unnecessary except dec through March and even then it's debatable.

But it is super effective.  I love my downriggers. Being able to fight a fish without the weight is a huge plus. But I'm using them less and less. Partly due to the extra drag and my laziness...no 100% because of that. Definitely not because of effectiveness.