Which Barometer Reading

[tjbrace]

I have a Garmin wind sensor that also provides atmospheric pressure on the N2K network, I also have a set of bulkhead instruments (Barigo) that includes a barometer. I have read both today and the Garmin showed 1017 whereas the Barigo showed 1041.
Which would you trust?

 

[pvb]

The Garmin.

 

[Gary Fox]

I would try and get the local pressure from a Met website, a local airport is likely to be closer than the BBC etc. Just for comparison.
I have three or four aneroids and they all disagree... but it's the movement up or down, and how fast, which I believe is useful.
I think your high reading one is showing an unusually high pressure though.
Edit, Stansted Airport is 1018, at 1340. Garmin wins!

 

[pvb]

Shotley Marina's website has a live pressure reading.

 

[Boathook]

The garmin seems more accurate if you are at West Mersea. As already mentioned it is the change that is important.

 

[VicS]

I have a Garmin wind sensor that also provides atmospheric pressure on the N2K network, I also have a set of bulkhead instruments (Barigo) that includes a barometer. I have read both today and the Garmin showed 1017 whereas the Barigo showed 1041.
Which would you trust?

Check the readings on a day when it is fairly steady and as close as possible to the average of 1013 mb with a reliable on line source such as XC weather, Wind Map - Britain Observations

For your West Mersea location todays readings of 1018m at Southend , London City airport and Shoeburyness and 1017 at Biggin Hill would be good readings to take as accurate
They will be more reliable than Yacht Clubs etc

Your Garmin is as near as its needs to be . Adjust the Barigo

 

[vas]

you are aware of the screw at the back of the Barigo right?
Mine was hardly every moving, puzzled tried to open it up and see what's inside, and surprisingly the regulating screw was completely missing!
Fitted one, adjusted to the digital one, works fine...

 

[penberth3]

I would try and get the local pressure from a Met website, a local airport is likely to be closer than the BBC etc. Just for comparison......

Yes. A lot of keen amateur observers have their own real-time web-sites. Anyone as keen as that will have accurate instruments. Worth looking for anything local.

 

[pcatterall]

I would try and get the local pressure from a Met website, a local airport is likely to be closer than the BBC etc. Just for comparison.
I have three or four aneroids and they all disagree... but it's the movement up or down, and how fast, which I believe is useful.
I think your high reading one is showing an unusually high pressure though.
Edit, Stansted Airport is 1018, at 1340. Garmin wins!

+1

 

[tjbrace]

Thank you all very much.
I wasn’t aware of the adjustment screw on the bulkhead Barigo. Friends bought the set for my 60 th birthday and it’s been screwed to the bulkhead ever since. That was a long time ago?

 

[Gwylan]

I have a Garmin wind sensor that also provides atmospheric pressure on the N2K network, I also have a set of bulkhead instruments (Barigo) that includes a barometer. I have read both today and the Garmin showed 1017 whereas the Barigo showed 1041.
Which would you trust?

As said, its the direction and speed that give the clue to the weather.

Google METARTAF and look for the local airport or airports. They will give you reasonable clue.

My pocket Chinese barometer keeps pretty good values and will be within a few mb of the local reading. Just have to remember to charge it up now and again.

 

[Spirit (of Glenans)]

I have a Garmin wind sensor that also provides atmospheric pressure on the N2K network, I also have a set of bulkhead instruments (Barigo) that includes a barometer. I have read both today and the Garmin showed 1017 whereas the Barigo showed 1041.
Which would you trust?

According to the UK Met Office's synoptic chart for today midday, the pressure in your area was predicted to be somewhere between 1016 and 1020, so 1017 seems about right. Do they still give Reports from Coastal Stations after the 2300 and 0500 Shipping Forecast? You could get the pressure at your nearest station from this to give you a comparison from which to calculate an offset.
If calibrating the your aneroid barometer by means of the adjusting screw, only infinitesimal turning of the screw is required. Usually it's a matter of turning it back and forth and tapping, until you get a reading that approximates whatever pressure is reported for your area.

 

[tjbrace]

According to the UK Met Office's synoptic chart for today midday, the pressure in your area was predicted to be somewhere between 1016 and 1020, so 1017 seems about right. Do they still give Reports from Coastal Stations after the 2300 and 0500 Shipping Forecast? You could get the pressure at your nearest station from this to give you a comparison from which to calculate an offset.
If calibrating the your aneroid barometer by means of the adjusting screw, only infinitesimal turning of the screw is required. Usually it's a matter of turning it back and forth and tapping, until you get a reading that approximates whatever pressure is reported for your area.

Thanks for your advice. TBH I don’t refer to the barometer much, I just get the forecast from XC when planning a trip. We don’t travel far now so long term weather is not too interesting as I have an old MIL (100 next month) to keep under control.
I shall take the Barigo from the bulkhead and try adjusting it to the Garmin at some time.

 

[jwfrary]

I would try and get the local pressure from a Met website, a local airport is likely to be closer than the BBC etc. Just for comparison.
I have three or four aneroids and they all disagree... but it's the movement up or down, and how fast, which I believe is useful.
I think your high reading one is showing an unusually high pressure though.
Edit, Stansted Airport is 1018, at 1340. Garmin wins!

coastguard have aneroid barometers you can request a reading if your at sea! -

don’t forget you need the reading reduced to sea level.

there’s likely a little screw in the back of your barometer that give you a little adjustment should it be needed

 

[Spirit (of Glenans)]

coastguard have aneroid barometers you can request a reading if your at sea! -

don’t forget you need the reading reduced to sea level.

there’s likely a little screw in the back of your barometer that give you a little adjustment should it be needed

Yes, if you have an FM radio with Airband you can tune into the continuous met report, (can't remember what it's called), and get all the current weather details. The atm pressure readings used by aircraft are actually reduced to Mean Sea Level.

 

[Praxinoscope]

We're lucky, our town hall which is only 100 yds from the harbour and about 3 ' above HW level, has a mercury barometer fixed in a window visible from the footpath, so it's very easy to obtain a very local check of the accuracy of the boats barometer.

 

[jwfrary]

Yes, if you have an FM radio with Airband you can tune into the continuous met report, (can't remember what it's called), and get all the current weather details. The atm pressure readings used by aircraft are actually reduced to Mean Sea Level.

VOLMET is on 5505 kHz is that what you mean.

sometimes you see both readings on a site

btw, I’m pretty sure the sensor in the garmin will be a BME 280 or similar from bosch, available for a few squid and easy to hook up to a raspberry pi.

 

[penberth3]

Yes, if you have an FM radio with Airband you can tune into the continuous met report, (can't remember what it's called), and get all the current weather details. The atm pressure readings used by aircraft are actually reduced to Mean Sea Level.

I thought all met stations reported pressure at sea level?

 

[Spirit (of Glenans)]

VOLMET is on 5505 kHz is that what you mean.

sometimes you see both readings on a site

btw, I’m pretty sure the sensor in the garmin will be a BME 280 or similar from bosch, available for a few squid and easy to hook up to a raspberry pi.

Here are the frequencies of the Volmet for the main, (international), airports in Ireland:
18.60 MHz

Frequencies

Airport	Tower	ICAO
Dublin	118.60 MHz	EIDW
Cork	119.30 MHz	EICK
Shannon	118.70 MHz	EINN
Knock (Ireland West)	130.70 MHz	EIKN

They are all available on an FM radio which is enabled for the Airband frequencies, which are just above the normal broadcast frequencies, between 108Mhz and 137Mhz. It's also possible to listen to all of the ATC frequencies. It's very easy to find out the frequencies used by your nearest airport, online.

 

[VicS]

I thought all met stations reported pressure at sea level?

Certainly all the pressures reported by XC weather, many of which are from airports, are sea level pressures.

What you have to remember if you adjust a barometer, intended for use on the boat, at home is to allow for the height of your home above sea level. I set my barometer 13 mb lower than the observation for Biggin hill