Cannon speed n temp for downriggers

[Bronlonius]

I recently bought a used, but almost new cannon speed n temp, it's similar to the newer cannon intellitroll or the depth raider.

It's incredibly useful for finding the thermocline, the temperature updates very quickly, but I've noticed that the depth reading is not very accurate. Does anyone have any experience with these, is there a way to calibrate them? I realize these are supposed to compensate for blowback, but as an example... even when not moving at all, my depth finder sees the downrigger weight at 50 feet, while the speed n temp sees it at only 44 feet. I trust my depth finder's reading, because if I drop the weight and hit the bottom, i can see that happening on my readout.

It included a spool of coated downrigger line, which the manual says is required for 100 feet or deeper depths, so I'm wondering if even though it works with the uncoated line, if it will be more accurate if I swap out my downrigger cable. I'm not sure how it calculates depth, if it's by pressure I don't think the cable should have anything to do with it but maybe I'm wrong?

 

[dingbat]

Re: Cannon speed n temp for downriggers

It's incredibly useful for finding the thermocline, the temperature updates very quickly, but I've noticed that the depth reading is not very accurate. Does anyone have any experience with these, is there a way to calibrate them? I realize these are supposed to compensate for blowback, but as an example... even when not moving at all, my depth finder sees the downrigger weight at 50 feet, while the speed n temp sees it at only 44 feet. I trust my depth finder's reading, because if I drop the weight and hit the bottom, i can see that happening on my readout.

According to the manual there is a depth compensation feature to account for the varying densities of the water.

Apparently a sonar device of some type but density wouldn't produce a 15% variance in 50' of water. The device is using the cable to transmit the signal so it's quite possible that some of the error is coming from poor signal quality brought on by not using the supplied cable. Either way, you have a method to adjust the depth w/o changing the cable

 

[Bronlonius]

Re: Cannon speed n temp for downriggers

I believe the online manual is for the newer "Intellitroll" version with a humminbird style head unit. Mine is the older discontinued version, the head unit is made by bottom line. Anyways, I found some more posts on another forum about my unit, and apparently if the head unit is not grounded directly to the hull it can also cause incorrect readings. I'm going to try grounding it directly to the hull first, and a fresh battery in the probe and see if it gets better.

They also say that wrapping a wet towel around the antenna helps it too.

 

[LongLine]

Re: Cannon speed n temp for downriggers

I can't explain the towel thing but I know guys that swear by it. Other than that are you sure your rigg'r is giving you the right depth? Most counters go by revolutions of the spool. i.e. geared to the spool. If you have a lot of cable or just a little on it then it will vary also.

Tom B.
(LongLine)

 

[Bronlonius]

Re: Cannon speed n temp for downriggers

Hi Tom,

I'm getting the actual depth from my boat's main depth finder. I can see the downrigger ball on it while I'm stopped or turning under the right conditions.even when completely stopped in calm water, the depth on the speed n temp is several feet shallower than the depth finder shows. There is a line counter on the rigger, which is within 1 foot of what the depth finder says when the rigger is vertical.