Luhr Jensen Speed Indicator/ tru troll

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ReelFunTimes
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Luhr Jensen Speed Indicator/ tru troll

Post by ReelFunTimes » Sat Feb 06, 2016 2:22 pm

I was wanting to know how many of you still use the Luhr Jensen tru troll speed indicator, i do have a question for those can supply advice.

1. Instructions say to mount near the Stern of the boat and this is where my mount is located, but it is also close to one of my down riggers, i wanted to move it more to the center slightly back towards stern but was not sure if this would be a good idea.

2. I do have gps speed but would rather rely on the tru troll to mark my speeds, so how many of you still rely on this old way of reading speed i am putting to much effort in to using it? this is something i have always been used to using for speed indication.

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Mike Carey
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Re: Luhr Jensen Speed Indicator/ tru troll

Post by Mike Carey » Sat Feb 06, 2016 6:46 pm

I was introduced to the Tru Troll years ago fishing with Anton Jones. He swore by it fishing on lake Chelan. I bought one and used it many years, until the base rusted apart fishing in the Sound. I never replaced it as it seemed to be unnecessary in this age of GPS apps on phones.

It should matter if you move it a few feet away from the rigger. IMO, it's best used to keep you in the proper speed range once you find biting fish. The accuracy of the number displayed I don't think is so critical. So in that regard, it's every bit as good as a GPS app.

Old School, but does the job!
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Larry3215
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Re: Luhr Jensen Speed Indicator/ tru troll

Post by Larry3215 » Sat Feb 06, 2016 11:40 pm

I think that if you want accurate water speeds, then something like the Luhr Jensen or a calibrated water wheel speedo is the way to go.

GPS only tells you your speed OVER THE GROUND. That could easily be vastly different from your water speed. If you are trolling with a 5 mph current and your GPS reads 5 mph, your water speed is zero. If you are trolling against a 5 mph current and your GPS reads 5 mph, your water speed is 10 mph.

With some experience, if you are using downriggers, you can judge the angle of the dangle on the ball to get you in the ball park.

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Mike Carey
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Re: Luhr Jensen Speed Indicator/ tru troll

Post by Mike Carey » Sun Feb 07, 2016 8:30 am

I must be dense and not able to figure this out in my head, lol. Doesn't gps track location and by that calculate speed? Why would it matter over water vrs. Ground? It's still measuring distance traveled. I do understand when trolling the sound I have to troll faster into the current to go the same speed as trolling with the tide. In any case, I do like the luhr Jensen troll indicators for visual cues, like downrigger cable angles.
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ReelFunTimes
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Re: Luhr Jensen Speed Indicator/ tru troll

Post by ReelFunTimes » Sun Feb 07, 2016 9:09 am

Thank you all for your reply's, one other thing i want make sure is the instructions say to mount the indicator by the stern of the boat, my down riggers are mounted at the stern, so am i asking for trouble or can i mount the indicator in the same location of the down riggers or can i get away moving it (speed Indicator) more towards the center of boat? Thanks Again.

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Larry3215
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Re: Luhr Jensen Speed Indicator/ tru troll

Post by Larry3215 » Sun Feb 07, 2016 9:11 am

Think about this example Mike.

You're on the Columbia river with the motor off, so your drifting with the current. Or you're in the sound drifting with the tide flow in a fast rip. Lets ignore wind and friction and drag and assume for a second that you are going exactly the same speed as the water. In reality you will be going slightly slower than the water - but close enough.

That means while you are drifting you have almost zero water speed. Your lure gensen speed sensor will will hang straight down under the boat and say you are moving at zero water speed because the water and the boat are moving at the same speed.

At the same time, your GPS will tell you you are going 5 mph or what ever speed the river or tide is moving at over the ground.

Now lets say you start the motor and turn into the current and throttle up until you are sitting still in relation to the shore. The water is now moving past the boat at 5 mph. Your Luhr Gensen will read 5 mph. BUT your GPS says you are sitting still = zero speed - because you are not moving relative to the ground.

Thats why the GPS is relatively useless for determining trolling speeds when there is any kind of current.

The key thing here is that you need to set your WATER speed so that you have the proper lure action. If you go by GPS speed, your lure may be going way to fast in the water or it may not be moving at all and have no action.
Last edited by Larry3215 on Sun Feb 07, 2016 9:17 am, edited 1 time in total.

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Larry3215
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Re: Luhr Jensen Speed Indicator/ tru troll

Post by Larry3215 » Sun Feb 07, 2016 9:14 am

ReelFunTimes wrote:Thank you all for your reply's, one other thing i want make sure is the instructions say to mount the indicator by the stern of the boat, my down riggers are mounted at the stern, so am i asking for trouble or can i mount the indicator in the same location of the down riggers or can i get away moving it (speed Indicator) more towards the center of boat? Thanks Again.
Im not sure why they want the Luhr Gensen at the back of the boat. Possibly because the water flow is more straight at the rear and would give a better reading?

In any case, I think as long as it doesnt get in the way of the downrigger or retrieving the ball, that you could mount it anywhere.

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Re: Luhr Jensen Speed Indicator/ tru troll

Post by G-Man » Sun Feb 07, 2016 9:25 am

this comes into play when you are trolling in moving water. Say you are at the Brewster pool and what to run your sockeye gear at around 1.0 mph. If you are using straight GPS readings it is important to determine the speed of the current and then factor that into your trolling direction with respect to the current's direction. With the Luhr Jensen Speed Indicator, it's not necessary. The indicator will provide you a true water speed, which is what will ultimately effect your gear's action. If you can remember back to your days in school, speed is relative to the point of reference. In this case, the reference to which the fish and your gear are concerned, is the water.

One thing to mention, the water wheels that hook up to your sonar units are generally inaccurate at speeds below 3 mph. You can try to calibrate them for trolling speeds, but I've found they don't provide consistent readings.

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Mike Carey
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Re: Luhr Jensen Speed Indicator/ tru troll

Post by Mike Carey » Mon Feb 08, 2016 8:49 am

thanks, that makes sense.
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