Vexilar Deptherm - Fishing Depth & Temperature Gauge

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Vexilar Deptherm (17421)
Vexilar Deptherm - Fishing Depth & Temperature Gauge
4.00 (in)
5.00 (in)
0.25 (in)
Minimum Purchase:
1 unit
Current Stock:

Frequently Bought Together:

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Find Feeding Fish Faster With Deptherm. Put science to work to give you a big fishing edge.

  • Tells you how deep it goes
  • Seeks out the right temperature
  • Helps you stay in the preferred range where fish are most apt to be feeding

How to Use:

The fishing odds are on your side every time you go out with a Vexilar Deptherm, model 104 fishing temperature gauge, for two simple but important reasons. It tells you quickly and accurately what temperatures are below your boat and it also tells you how deep these temperature ranges go. Thus, if you have the temperature chart, you quickly know whether you're fishing in a spot where the fish are most apt to be. If your Vexilar Deptherm fishing temperature gauge shows the water too cold or too warm for the species you're after, you can quickly move just as the fish do. You won't be wasting the day in the wrong place.

Deptherm works like this: dropped on a line, growing pressure forces water into the tube as the instrument descends. The volume of water trapped in the tube serves as a depth measurement column and is read off the side of the tube calibrated in feet. The thermometer on the other side assures close temperature readings if the instrument is left down for 30 seconds.

General Application - Attach the Vexilar Deptherm fishing depth gauge to line and let sink to bottom or any intermediate depth. Hold there for 30 seconds and return to surface. Read depth on the calibrated side at the top of the water column and temperature off the temperature plate. Invert instruments; press valve to release water. Shake until all water is out before using again.

Downrigger Application - Clip the Deptherm Model 104 to your downrigger ball for monitoring water temperature and depth at the downrigger. When raising the ball for re-rigging, check the temperature and depth. Temperature readings on the Deptherm will not change while ball is being raised due to a delayed reaction (1 to 2 minutes).

Species Preferred Temperature Chart:

Degrees Fahrenheit
Lake Trout
Rainbow Trout
Brown Trout
Brook Trout
Landlocked Salmon
Sockeye Salmon
Largemouth Bass
Smallmouth Bass
White Bass
Perch (White, Yellow)
Walleye Pike, Sauger
Northern Pike
Chain Pickerel
Sunfish, Bluegill, Crappie
Channel Catfish

Customer Reviews

7 reviews

  • The "Deptherm" is an essential part of the successful fisherman's tackle box. I use mine on my down rigger. Works great and you can't beat the price. I do have a spare just in case.

  • Great for the prices.

  • I fish for trout and salmon most of the time, knowing the water temperature is important when targeting a species of fish. My fish sonar tells where the fish are but the water temperature helps me to figure out the species. I connect the thermometer to the downrigger weight and when I pull up the weight, I quickly read the temperature. Simple and effective. I don’t use the depth feature since I use line counters on the downrigger and reels. Compared to where money is spent on a fishing hobby, this is a low cost investment and provides useful information. Example, I was fishing for kokanee at 100ft deep, I noticed several fish at 50 ft on the sonar. I took a temperature measurement at 50ft and it was 61 f, that is the water temp Rainbow trout prefer. It’s that easy.

  • The "big outdoor store" and "big fishing store" don't carry deptherm. I haven't used the deptherm yet,but my shopping /purchasing experience was as I hoped. My order was confirmed and shipped the next day. The product arrived in good condition and it's a matter of time until I get out on the lake and use it. I can't rate the product 5 stars because I have yet to use it.

  • Quick, easy to use and affordable. This is a good low cost way to target temperature zones and appears to be relatively accurate (depth and temperature). I've only used this during the summer so we will see how well it performs during ice fishing season. great value!

  • There are two sides to read on this device; on the front is a thermometer, and on the back is a scale that indictates depth based on how much water enters the vial through a small hole. The depth measuring aspect doesn't work. The whole vial fills up to the 100 ft mark when I lower the deptherm to 30 feet (as measured on a line counter trolling reel, and it shows up on the depth finder as I lower/raise it). So don't trust the depth scale. I still like it, though, because I attach it to my downrigger, at a known depth, and after 10-15 min of trolling all the water in the vial should be very close to the temperature at that depth layer. When quickly cranked back up the water in the vial should keep the thermometer reading from changing much just from a few seconds of reeling through shallower and warmer water. The plastic case and small amount of water probably insulate the thermometer bulb enough as it's raised to give a close temp at the depth. Just be sure to have a way to tell how deep it really is (mark you line, use a line counter reel, use a downrigger, etc.).

  • Having used the Vexilar Deptherm in my pond and natural lakes for at least 10 years I was thrilled with its accuracy and economy. After many uses the valve to empty the sample water dislodged and I needed a new one. to the rescue. Most retailers had none in stock and could not replace their inventory this late in the start of the season. The Vexilar Deptherm is indispensable if you have to track temperature and depths and it doesn't cost the amount of a fancy piece of electronics for simple use.

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