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thermometers???

L

Leon Dodd

Senior Member
this has probably been discussed on here before and did find a little info in the FAQ's but just wanted a little more up to date info/opinion,
i am looking to buy a reuben heaton model would prefer the digital one for ease of use but is the standard one more accurate? and how would you reccomend testing the accuracy?
thanks in advance, leon
 
I bought a digi thermometer from Clas Ohlsen for a couple of quid which seems to work fine. Doesn't matter if it is half a degree out - it is the trend up or down that is important.

Steve
 
I bought one off ebay last year, just a very basic Alcohol thermometer in a stainless tube. Works for me. Think it cost me a fiver. One benefit with a standard theromoter is you can tie it to your landing net, of even a spare rod and make sure you get a reading as deep as possible. Yesterday on the TT i was getting 8C in the edge, but 6C when put in 5 feet of water.

Jon
 
best way to test a thermometers accuracy is to test boiling water, you should get a reading of 100oC +/-1oC and test it on iced water again it should read 0oC +/-1oC.
if you get a reading of 101oC on boiling water you usually get 1oC in iced water like wise if its 99oC on boiling water its usually-1oC. ( sometimes they go 2oC) if your thermometers out by 1/2 degree doing this will tell you, so when your on the river bank you know to knock off or add a bit of temp.
i use a reuban heaton and have found them to be very accurate but i callobrated my on a regular basis.
cheers
jerry
 
You test a digital thermometer for accuracy using the ice point test.

Google it or look here:
http://www.temprecord.com/ice.pdf

...which is just a long winded way of saying get a cup, put a load of crushed ice in it (or scrape the "snow" off the inside of your fridge freezer compartment), top the ice up level with cold water and poke the thermometer's probe well into it.

After a while you should get a reading of 0.0c or very close to that (my thermometers flicker between 0.0c or 0.1c).

Another (guide only) test is to stick the thermometer probe under your tongue and see if you get 37.0 c but that obviously involves many subjective factors.
 
Just saw Jerry's post so apologies for any repetition. Personally I wouldn't put the plastic probe or cable of my therms anywhere near boiling water in case it damaged them but each to their own. :).
 
Jerry Gleeson said:
best way to test a thermometers accuracy is to test boiling water, you should get a reading of 100oC +/-1oC and test it on iced water again it should read 0oC +/-1oC.
if you get a reading of 101oC on boiling water you usually get 1oC in iced water like wise if its 99oC on boiling water its usually-1oC. ( sometimes they go 2oC) if your thermometers out by 1/2 degree doing this will tell you, so when your on the river bank you know to knock off or add a bit of temp.
i use a reuban heaton and have found them to be very accurate but i callobrated my on a regular basis.
cheers
jerry
Click to expand...

Actually Gerry the temperature at which water boils is dependant on barometric pressure and altitude, so if you live on the top of a hill and test your boiling water in a snow storm you will get a very different result to the bloke who lives on the coast and measured his boiling water in the middle of a heat wave.
 
The Celcius( centi i.e hundred division) scale has two fixed points which are needed to establish the scale.They are 0 deg C taken to be the temperature of pure melting ice and 100 deg C the temp of steam above boiling water at standard temp and pressure. (temp of impure ice not always 0 deg C so reason ice melts when salt is added as it lowers the freezing point), Impure(solids added such as salt) water boils at above 100c and different pressures can affect boiling points -hence the use of the pressure cooker.
But hey, as has been said it is the trend that is important and these digital devices are not too accurate. A good old alcohol thermometer is probably as accurate as any but it isn't knowing the temp that will catch you fish it is how it has varied or not over recent days that counts.
 
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Adrian- Barometric pressure varies with height so it is the same variable and not a different one. It is one reason why a cup of tea up everest is not the same at base camp(even yorkshire tea) as the boiling point of water is around 70C at the top of everest which does not produce a good cuppa! Snowstorms and heat waves have nothing to do with boiling points - only atmospheric pressure. High pressure equals high boiling point(sunny or not) so if potatoes are cooking in steam at 120 deg c (steam at standard atmospheric pressure or 760 mm Hg is 100 deg C) as in a pressure cooker - less time is needed to cook them.
geoff
 
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Adrian,

Professor, I now see why the syndi runs on Tea. I never knew there was so much science involved:D:D:D



Paul
 
thanks for all the replies,
as many have you have said it is the temp. trend which is more important, but a little more info in my notebook may help in seasons to come.
a query for Jerry, how do you callibrate your thermometer?
cheers guys, leon
 
Jon Frisby said:
I bought one off ebay last year, just a very basic Alcohol thermometer in a stainless tube. Works for me. Think it cost me a fiver. One benefit with a standard theromoter is you can tie it to your landing net, of even a spare rod and make sure you get a reading as deep as possible. Yesterday on the TT i was getting 8C in the edge, but 6C when put in 5 feet of water.

Jon
Click to expand...

Have you ever tried a Smartcast to provide you with a temperature reading? I have heard that they are very good.
 
I use a Smartcast at times but they show the water tempertaure in the top inch of the water and that tends to be different to what is going on further down and away from the margins.
 
Will Smith said:
You test a digital thermometer for accuracy using the ice point test.

Google it or look here:
http://www.temprecord.com/ice.pdf

...which is just a long winded way of saying get a cup, put a load of crushed ice in it (or scrape the "snow" off the inside of your fridge freezer compartment), top the ice up level with cold water and poke the thermometer's probe well into it.

After a while you should get a reading of 0.0c or very close to that (my thermometers flicker between 0.0c or 0.1c).

Another (guide only) test is to stick the thermometer probe under your tongue and see if you get 37.0 c but that obviously involves many subjective factors.
Click to expand...
You can stick it up your arse. Much more accurate. You can get a chum along to help. The trouble with a thermometer under the tongue is that when you take the thermometer out to take a reading, the temperature immediately starts to drop. However in a rectum, your chum can take the reading whilst the thermometer is in place. Any calibration can be carried on the bankside. To demonstrate the accuracy, your chum could then place the thermometer under his tongue.
 
Tut Tut youngsters reading this...
 
Geoff Blakesley said:
Very useful Jim- you must enjoy the small world that you live in
Click to expand...

My "contribution" was not personal and was intended to be lighthearted. You do require a modicum of humour to enter my small World. After a day's work, or not, a discussion on the triple point of water is not something that would inspire me, or, probably many others on this forum. Get a life!
 
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