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Old 31-01-2017, 10:10   #91
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Re: Do I really need a barometer? Which one?

I am pretty sure the phones have a built in pressure transducer, but if they were downloading it off the internet, that would explain the accuracy.
If anyone has an airplane altimeter laying around, you can use that as a barometer, just adjust the altitude to zero and read the pressure in the Kollsman widow, pretty accurate.

I tried one or two barometer Apps for my Iphone 6S several months ago, I was less than impressed with the accuracy, but maybe Iphone 6S's have a crappy transducer, or maybe just mine does
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Old 31-01-2017, 10:58   #92
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Re: Do I really need a barometer? Which one?

Maybe watching the horizon is the ticket for fronts. Run like hell for safe harbor or batten down.
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Old 31-01-2017, 11:15   #93
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Re: Do I really need a barometer? Which one?

Iíve used a digital barometer for years now. Itís part of my Kestrel 4000 weather instrument. It records weather data every hour (temp, pressure, humidity, plus a bunch of derived factors and windspeed) and charts it going back about 10 days. Great to see trends.

I also use a standard bulkhead mounted barometer that I use for log book entries. I set the marker needle every morning, so I can quickly see how itís moved through that day, but the hourly digital graph is easier to see trends.
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Old 31-01-2017, 11:27   #94
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Re: Do I really need a barometer? Which one?

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Stu,

Thanks for asking my question. It would seem to me, also low tech, if the pressure readings are not measured where you are, they are not worth a thing.

I'm guessing the old recording barometer with the stylus and round piece of chart paper have a better onboard replacement digitally. Of course the analog one didn't rely on power just a key an remembering to use it.
You are utilising the barometric pressure measured at distant locations every time you look at an MSL Analysis.....

Monitoring a single - local - source such as the barometer at your local airport will be no different to watching your ship's barometer.
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Old 31-01-2017, 11:39   #95
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Re: Do I really need a barometer? Which one?

A barometer can be useful, but un necessary if you have other good weather collecting info. General info is gained from the barometer, but you must know the specific area normal conditions and influences for it to be useful.
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Old 31-01-2017, 13:25   #96
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Re: Do I really need a barometer? Which one?

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Originally Posted by El Pinguino View Post
You are utilising the barometric pressure measured at distant locations every time you look at an MSL Analysis.....

Monitoring a single - local - source such as the barometer at your local airport will be no different to watching your ship's barometer.
I don't get it. If you're not tied to the dock at your airport, Several miles off shore may be entirely different. If the front isn't coming from the direction of the airport.

Your eardrum may detect a pressure change close by.
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Old 31-01-2017, 14:08   #97
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Re: Do I really need a barometer? Which one?

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I don't get it. If you're not tied to the dock at your airport, Several miles off shore may be entirely different. If the front isn't coming from the direction of the airport.

Your eardrum may detect a pressure change close by.
Actually, unless you choose to calibrate just as a front passes by, the gradient is not steep enough to introduce much error in a few miles distance. Getting it to the nearest mb is plenty close enough, and if there is more than a mb difference in a few miles, it is likely blowing so hard you will have other things on your mind!

Here in Oz, checking the observations on the BOM web site will often show a reporting station within a reasonable distance. This is a good means of checking one's barometer for calibration.

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Old 31-01-2017, 14:17   #98
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Re: Do I really need a barometer? Which one?

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Actually, unless you choose to calibrate just as a front passes by, the gradient is not steep enough to introduce much error in a few miles distance. Getting it to the nearest mb is plenty close enough, and if there is more than a mb difference in a few miles, it is likely blowing so hard you will have other things on your mind!

Here in Oz, checking the observations on the BOM web site will often show a reporting station within a reasonable distance. This is a good means of checking one's barometer for calibration.

Jim
I guess for calibrating it is fine. I am not sure the actual reading is as important as the change?
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Old 31-01-2017, 14:17   #99
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Re: Do I really need a barometer? Which one?

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Stu,
Will your phone barometer work out of cell phone range? If not, would you need a satellite connection for the readings offshore or is the sensor built into the phone.. . questions asked honestly from a purposeful low tech sailor. Thanks.

Yes - all it uses in the built in pressure sensor.

The only thing you won't be able to do is check against an airport QNH.
But once you are calibrated, you don't need that. And since you are always at sea level, you can always adjust so that your altitude is zero.
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Old 31-01-2017, 16:37   #100
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Re: Do I really need a barometer? Which one?

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I guess for calibrating it is fine. I am not sure the actual reading is as important as the change?
Yes, generally true that the change and the rate of change are the important matters. However, as a retired boffin, I do appreciate instruments that are correctly calibrated! And there are times when it is useful to compare your current readings with those on the MSLP chart... helps me predict (or guess) about future developments, and for that, calibration matters.

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