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> > Good, Reliable Stream Thermometer

WiflyfisherJune 21st, 2008, 2:18 pm

Posts: 663
I am debating on what is best thermometer to get for measuring stream temperatures. I looked at a couple of older threads on other forums and there wasn't anything clear cut. Some are using cheap kitchen-type thermometers, some are using the mercury stick-type thermometers made specifically for use in streams and lakes and others are using more expensive digital thermometers. Any suggestions?
John S.
GONZOJune 21st, 2008, 2:56 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
After losing two conventional thermometers, a friend made me a present of a William Joseph digital thermometer. I really like it. The problem with the others was that I would put them in the water while I was preparing to fish and then forget about them. The new thermometer only takes a few seconds to get to temperature and never leaves my hand during the reading.
WiflyfisherJune 21st, 2008, 3:00 pm

Posts: 663

So you are recommending this one... right?

John S.
GONZOJune 21st, 2008, 3:05 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
That's it. Just make sure you remove your polarized glasses, or you won't be able to read the screen. I suspect that may be because the screen is polarized, but I'm not sure.
CaseyPJune 21st, 2008, 6:36 pm
Arlington, VA/ Mercersburg, PA

Posts: 653
unlike Best Fishing Buddy, i just refuse to use electronics on the stream. my stick-shaped "mercury" one lives on a zinger in my Mayfly pocket and when i reach a convenient spot, into the water it goes--and back out again! within a couple degrees is good enough, right?
"You can observe a lot by watching." Yogi Berra
GONZOJune 21st, 2008, 7:45 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
Casey, I bet you still wind your watch. Just teasing--there's nothing wrong with analog/mercury if you keep it attached to you, and within a degree or two is generally good enough. Still, I don't miss squinting at the mercury column and the tiny numbers/lines. The best thing about the digital deal (for me) is that I can watch the numbers dropping until they hold steady, insuring that I have a good reading. The thermometers that I lost were on zingers, but I ended up detaching the zinger from my vest so that I could assemble my gear or do a seine sample while making sure I kept the thermometer in the water long enough to get a good read. That works too, as long as a rising trout or something exciting in the sample doesn't make you forget the thermometer. My bad. :(
KonchuJune 21st, 2008, 8:12 pm
Site Editor

Posts: 505
Gonzo, you're right about the LCD screen being polarized.

Although digital thermometers may be more precise, it doesn't mean they are more accurate than their analog or mercury counterparts. We are often swayed into thinking that digital provides better data. It can, but not always.
GONZOJune 21st, 2008, 8:42 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
Thanks, Konchu. I just guessed that might be the problem because the effect was much like the blackout you get when you take a pair of polarized glasses and turn them ninety degrees to another pair. And despite teasing Casey, I'm still basically an analog guy who got dragged into a digital world. My comment about a degree or two was more about the accuracy of the reader than the thermometer.
WiflyfisherJune 22nd, 2008, 3:37 am

Posts: 663
Actually I am looking for accuracy as well as easy to read. Otherwise, why use one at all? Two-three degrees difference to me is huge, especially on warmer rivers.

Up to now I have always used an analog mercury thermometer that I used like CaseyP. Besides loosing them I also found them difficult to read accurately.
John S.
FlybyknightJune 22nd, 2008, 9:13 am
Milton, DE

Posts: 82
I have a 6" glass/Mercury type encased in a SS
perforated case that hangs on a string from my wading belt.

Lightly on the dimpling eddy fling;
the hypocritic fly's unruffled wing.
Thomas Scott
CaseyPJune 22nd, 2008, 6:07 pm
Arlington, VA/ Mercersburg, PA

Posts: 653
gee, no Luddites here, just a refusal to have a battery die in the middle of a fishing outing...Best Fishing Buddy always knows the temp before and better than i do if the battery is working. he recommends it very much and thinks you would be happier with one. he's also used one of those laser thermometers that measures surface temps, but we weren't sure if it was measuring the top of the water or the bottom of the streambed, so he went back to the dippable digital. i'll ask him what kind it is.

i feel a hijack coming on, but it relates to how to use a thermometer.

the zinger string is sort of short, so perhaps my thermometer is not staying in the water long enough. i swish it around for about 30 counted seconds. if my hand gets too cold to hold it under water any longer, it's cold enough/too cold for fish. i take my hand out of the water and watch the red stripe as best i can sideways unless my teeth are chattering too hard, in which case, bag it, just fish for a while and then go home.

if my hand doesn't get too cold, it's warm enough/too warm, and i can really watch the bright red stripe creep up and down the little number scale until i decide which condition it is. Wiflyfisher is right: those last two degrees are crucial, so it's good they're easier to read! if it's too warm, fall in the water on the way out of the stream and go find something else to do. the car is full of little field guides so weed, tree, flower, insect, and bird identification are all on the menu.

please forgive me if this was not helpful; how long do you keep your thermometer in the water?
"You can observe a lot by watching." Yogi Berra
CaseyPJune 22nd, 2008, 6:10 pm
Arlington, VA/ Mercersburg, PA

Posts: 653
argh!! Big borther is watching: just below my last posting up popped a icon all ready to look for "fish thermometers". and you wonder that i'm paranoid...
"You can observe a lot by watching." Yogi Berra
GONZOJune 22nd, 2008, 9:48 pm
Site Editor
"Bear Swamp," PA

Posts: 1681 long do you keep your thermometer in the water?

It depends, but forever is probably too long.
MartinlfJune 23rd, 2008, 4:49 am
Palmyra PA

Posts: 3233
I've attached one end of a fairly long (about 4'I'd guess) piece of one of the super thin braided lines to my old fashioned glass in a steel frame thermometer and the other end to a small clip that attaches to a D ring on my vest. I wrap the line around the themometer to get it out of the way, stowing the whole thing in one of those small long thin pouches in my vest. The thermometer can go in the water at any time, stay a while as I rig up or change a fly, then be reeled up when it's convenient. Since it isn't unclipped from my vest it doesn't get lost, and I haven't managed to break this one yet. If I were to carry a digital one, I'd slip some extra batteries in a little ziplock bag and stow that in my vest somewhere, though. Perhaps when the kids are out of college and making money rather than spending it faster than it comes in, they'll buy me one of the new models.
"He spread them a yard and a half. 'And every one that got away is this big.'"

--Fred Chappell
TrtklrJune 26th, 2008, 5:57 pm

Posts: 115
I use a cooking thermometer I know that sounds a little crazy but it works, I am talking about the ones that the dept. of health recommend. they have a stick type shaft about 4 1/2 inches long with a scale a little smaller than the size of a quarter on top. it's durable, water proof and cheap, best of all it is adjustable. by adjustable i mean you can take it put it in a glass of ice, not ice water, and set it to 32 degrees with a wrench. you know its accurate, its easy to read, and small (actually I sell them for 19.99 no just kidding).they are about 5 bucks buy them from a restaurant retailer for better quality.
I have seen nothing more beautiful than the sunrise on a cold stream.
WiflyfisherJune 26th, 2008, 6:17 pm

Posts: 663
Its funny you mention the cooking thermometer. I did make it to Cabelas earlier this week, but instead of buying the digital thermometer I bought a inflatable pontoon boat for fishing some of the small trout lakes by me. I figure I will just "borrow" my wife's cooking thermometer when I go off to the river to fish. :)
John S.
GONZOJune 26th, 2008, 7:38 pm
Site Editor
"Bear Swamp," PA

Posts: 1681
Geez, John, when you said that I gave you an excuse to go to Cabela's, you didn't mention that it was an excuse to buy a pontoon boat. Nicely played, pal! ("Honey, I'm going to Cabela's to buy a new thermometer.") Enjoy the boat. :)
KinzuaJune 26th, 2008, 10:51 pm

Posts: 20
Another vote for the William Joseph digital. Expensive, but accurate. Mine's three years old and still running on original battery. Not sure how waterproof it is - haven't dunked it - but have used it in damp conditions with no problems.

So, I'm not the only one who has left their thermometers streamside waiting for equilibration.
WiflyfisherJune 27th, 2008, 5:40 am

Posts: 663
Gonzo, it wasn't quite like that. I have been looking online for a while at pontoon boats. We have some neat small trout lakes within 1/4 mile to 5 miles from us and no one ever fishes them. They have brookies, rainbows and browns in them. In the warmer summer months I have been thinking it would be great to spend some time checking these small lakes out.

Kinzua, thanks for the vote for the William Joseph digital. I will have to make another trip back to the store. :-)
John S.
Kschaefer3April 11th, 2014, 11:03 am
St. Paul, MN

Posts: 376
This is quite an old thread that I would like to bring back. I had an analog stream thermometer, the kind at the fly shop in the black sleeve. I noticed the mercury had separated, so I bought another. Within a week the mercury separated on that one too.

Now, $10 is not a lot of money, but I don't want to be spending $10 a week on a new thermometer. I fish similar areas to John S., so knowing the exact water temp can be very critical to me.

John - What thermometer did you end up getting? After 6 years, do you still have it/like it?

Does anyone else have any other opinions on stream temps?

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