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Discussion Starter · #1 ·
Does anyone have a chart or a math calculation to show the depth of your cannonball with various degrees of swayback? I've heard of the Osprey Computrac but I can't find it.

Thanks, MikeC
 

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I've not heard of any charts but there may be one to get you somewhat close.

There are 4 variables that would effect the chart and it's accuracy.

Weight of the ball, boat speed, current direction, and ball depth. Any change in any one of these can and does have a noticeable effect in cable angle.

The problem I would see in any chart is just a couple of degrees of cable angle change, compounded by the variables would have a fairly significant impact on actual depth calculations. It is difficult to measure by eye small changes in the cable angle.

Don't your down riggers have depth counters?

You can also get approximate depths by slowing your speed to keep your balls in the depth finder cone angle and they will show up on you graph. However remember that your balls when at most trolling speeds (depending on ball weight, current and speed) will be on the outside of your cone angle and show up as deeper on your graph than they actually are running. The difference will once again depend on the variables. The difference could be a foot or two or more.

Like any line counter reel or depth counter on a down rigger knowing the exact depth is not as important as repeatability. The counters let you reset a lure at a given reading, whether it is 36 ft or 40 ft doesn't really matter as long as it's working and you can return to that same depth or make changes and be able to measure any changes in depth presentation that you make.
 

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Lumberjack
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You can also get approximate depths by slowing your speed to keep your balls in the depth finder cone angle and they will show up on you graph. However remember that your balls when at most trolling speeds (depending on ball weight, current and speed) will be on the outside of your cone angle and show up as deeper on your graph than they actually are running. The difference will once again depend on the variables. The difference could be a foot or two or more.
Ball weight, cone angle, trolling speed, deeper on the graph...The only thing I can do is slow my speed! All of the things that come to mind! :p

I was robbed! My balls don't do this :mad: ...and talking in terms of a foot or two?? Man...I would be happy with a few inches! :D :D

Kim...you must be "DA MAN"!!!! :D
 

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Defensor Fortis
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Set your fish finder to arches instead of fish ID's. Then set your sensitivity on your fish finder until you start to see a black line(s). That black line will be how deep your rigger ball are. If I set LC on my rigger at 35' it will show up around 33' on my finder. I usually have 2-3 feet difference with the arch on my setup depending on the depth.
 

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I'm with Lundy, Dont over think there just fish
with pea size brains. Repeatability is the key.
If your not catching any fish, vary your depths
a few feet at a time. On my boat I run 2 riggers
at different depths along with dipseys and
jets. Find the program and go from there. If
the fish are that picky I doubt you'll catch many.
 

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Discussion Starter · #7 ·
I think everybody's missing the point. I'm only interested in the effect of swayback. What I'm trying to figure is, for instance, if I've let out 40 feet and the downrigger line's on a 45 degree angle, which is extreme, the ball would be running at 20 feet. Yes, my downriggers have counters, but that doesn't really help with swayback. I think 1 foot per 10 at a normal trolling speed 2 to 3 mph should be close, but I was just trying to confirm this.

Toxic, if you have your keel offset correctly configured, that would be about what was I figuring. 1 foot per ten. looks like maybe that's a little long if you're showing 2 feet at 30, but without the angle of the arc it becomes totally speed dependent.

Thanks for the replies

MIkeC
 

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Defensor Fortis
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MikeC, another factor will be your ball poundage. The heavier the less arch (I'm sure you knew that). I am running with 8lb's. I would like to move up to 10lbs. But for now I'll save some money and just watch my screen.
 

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Discussion Starter · #9 ·
Really I think the only factors are the depth you're fishing in, the amount of line out and the degree of arc of the line to your ball. everything else affects this but with those three numbers you can calculate the ball's distance from the bottom.

Roger23 I don't believe that calculator will work because it isn't a right angle anymore; it's a polygon. at least I think it is. so if there's a calculator that you can plug in the arc, the distance down and the hyptenuese to get the fourth leg, ie., the distance from the ball to the base, that'd be the one to use. I think I found it but they were talking about sines and cosines and I was lost right about there.

Thanks, MikeC
 

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Defensor Fortis
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.

Roger23 I don't believe that calculator will work because it isn't a right angle anymore; it's a polygon. at least I think it is. so if there's a calculator that you can plug in the arc, the distance down and the hyptenuese to get the fourth leg, ie., the distance from the ball to the base, that'd be the one to use. I think I found it but they were talking about sines and cosines and I was lost right about there.

Thanks, MikeC

Man, you know all them big words and you can't figure it out LOL. I feel ignorant now :p
 

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Does anyone have a chart or a math calculation to show the depth of your cannonball with various degrees of swayback? I've heard of the Osprey Computrac but I can't find it.

Thanks, MikeC
Mike, heres a link for any professional questions you would ever need about downrigger questions. There is a ton of info...you might want to join the site.
Van

http://www.michigansportsman.com/
 

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a few basic things to remember. The heavier the ball the less current and speed affect it. But the more of a pain it is to swing up and attatch to the release. The cable dosent take a straight path to the ball. Its curved due to the water resistance so if you try to calculate based on a right triangle you would be way off.
If you are marking fish on your screen as arcs. The the bottom of the arc is when the fish is on the outermost part of the cone. That is close to the level that you would want to mark you downrigger since its on the outside of the cone angle too. IF in fact you want to fish at the exact level of the fish.

It really dosen't mater that much since its a known fact especially with salminoids that they love to stay down in cold water and dart up into the warmer water to grab their pray. So being above the fish may be better sometimes.

I guess this would matter the most if you are trying to scrape fish off the bottom in deep water. I beleive most salmon charters that do this in water of 60-90 ft routinely use 14lb balls and just bump their cables a couple of feet deeper. I know ive hit bottom in 80 ft with about 87 ft of cable out at speeds around 2.4-2.7 with a twelve lb ball.
 

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design of the balls per weight also comes into factors, like, those fish shaped ones dont track true, a round ball will track better.
 

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My new Mag 5 HS's owener manuals have the exact chart that you are looking for. If you want me to I can scan it in for you. Just let me know.

Also, it is called "blowback".

JD
 

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i just watch mine on the lowrance. it will be a straight line all the way across the screen. you can even see it when it comes up. like toxic said, set the screen to arches not fish symbols. fish symbols will show you a line of little fishes at one depth. found this out the hard way:eek:
 

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Defensor Fortis
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i just watch mine on the lowrance. it will be a straight line all the way across the screen. you can even see it when it comes up. like toxic said, set the screen to arches not fish symbols. fish symbols will show you a line of little fishes at one depth. found this out the hard way:eek:

Ahhh.....simplicity at it finest. To much info boggles the mind.
 

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You can also change the wire cable to braided line sold by Cabelas for downriggers. It has less bow because of its smaller diameter. It also does not sing at higher speeds. I have used for about 2 years now with better success
 

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40' of cable out at a 45 deg angle blowback would put you at 29-30 down.

40' of cable out at a 22 deg angle blowback would put you at 36'
 

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Discussion Starter · #20 ·
JD, a copy of that chart is exactly what I"m looking for. I sent you a pm too.

Lundy, I used a six-inch scale for 40 @ 45 degrees and I got 11.66 feet off the bottom. I tried to do it in the yard but my numbers were way off.

Thanks to all who replied.

MikeC
 
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