Electronic Barometer/Barograph What are important features?

[El Pinguino]

Originally Posted by Paul L

I would much prefer a stand alone device, as you'll want to check it while at anchor when the chart plotter is off.

What he said ^^^^

Meanwhile

'In the tropics the barometer almost always stays within a three-millibar range (plus or minus 1.5mb from the norm). Any deviation is cause for concern.
Even a three-millibar deviation, above or below the norm, signals the onset of a low pressure system, and this is one of the key ingredients for the birth of a cyclonic storm.'

That is from here.. https://www.setsail.com/mwh.pdf .. page 352

[Onemoreproject]

Wow. So much great info. Thanks!

[conachair]

Originally Posted by Paul L

I would much prefer a stand alone device, as you'll want to check it while at anchor when the chart plotter is off.

Heading slightly towards geekiness, but a Raspberry Pi draws little enough for many boats to leave on all the time as a boat nav system , this is what a BMP180 output looks like..

[Paul L]

Originally Posted by conachair

Heading slightly towards geekiness, but a Raspberry Pi draws little enough for many boats to leave on all the time as a boat nav system , this is what a BMP180 output looks like..

A Pi with a small display powered by the boats 12v system would be fine. Always available and low power draw.

[conachair]

Originally Posted by Paul L

A Pi with a small display powered by the boats 12v system would be fine. Always available and low power draw.

Or you can actually do it all over wifi, the screen shot is of a web page. Works great, the Pi can go weeks before a reboot.

[Paul L]

Originally Posted by conachair

Or you can actually do it all over wifi, the screen shot is of a web page. Works great, the Pi can go weeks before a reboot.

As mentioned above, I'd rather have a stand alone unit that I can look at whenever I want without involving another device.

[a64pilot]

Originally Posted by Paul L

Do you really think that you will actively be making different passage decisions based on an NIST calibrated barometer vs my single point calibrated Meteoman unit? In this case close is good enough and relative changes are more interesting than absolute.

Originally Posted by El Pinguino

What he said ^^^^



Meanwhile



'In the tropics the barometer almost always stays within a three-millibar range (plus or minus 1.5mb from the norm). Any deviation is cause for concern.

Even a three-millibar deviation, above or below the norm, signals the onset of a low pressure system, and this is one of the key ingredients for the birth of a cyclonic storm.'



That is from here.. https://www.setsail.com/mwh.pdf .. page 352

Based on the second quote, yes, maybe.
I agree rate of change and total change is more important than being certain that the pressure is the number reported, but without a multipoint calibration, how can you tell is an instrument like a multimeter for instance or a torque wrench is accurate throughout its range?
Just for reference anything that I used for FAA test flights had to have a multipoint calibration certificate within 90 days.
Now I’m not going to send this thing off for calibration, ever, but if you can get a product for the same or less money that is calibrated to NIST standards and comes with the Cal card why wouldn’t you?

[Exile]

Originally Posted by Onemoreproject

Thats what this forum is all about. Examining theoretical situations with real life experience.
Thanks!

What do you think about this stand alone device vs one incorporated in a chart plotter? I found this one for 125.00 which is 75.00 less than the MateoMan. Difference between this and MateoMan is in the display and it only stores 24 hours of history.

https://www.thomassci.com/Instrument...le%20Barometer

Others with more long-distance experience can correct me, but I would think you'd want more than 24 hrs. of history stored for purposes of seeing trends.

[Exile]

Originally Posted by Paul L

I would much prefer a stand alone device, as you'll want to check it while at anchor when the chart plotter is off.

When at anchor my plotter is usually on for the anchor watch function, but is a bit of an energy waster. But then some advocate keeping their radar on at anchor. But of course now there are apps for anchor watch too. I would still want stand-alone for an electronic barograph so I have the option of shutting higher energy consuming electronics down.

[El Pinguino]

Originally Posted by Exile

Others with more long-distance experience can correct me, but I would think you'd want more than 24 hrs. of history stored for purposes of seeing trends.

You could write it down in your log... radical I know...

[El Pinguino]

Originally Posted by conachair

Heading slightly towards geekiness, but a Raspberry Pi draws little enough for many boats to leave on all the time as a boat nav system , this is what a BMP180 output looks like..

Any chance of being shown how to set that up? Be aware that I am thick as a brick when it comes to doing interesting things with a raspberry pi.....

[Exile]

Originally Posted by El Pinguino

You could write it down in your log... radical I know...

As in . . . no keyboard or screen? With an actual pen or pencil?? And in one of those logbooks that actually contain paper??? Say it ain't so . . . .

[hzcruiser]

This is what we're working on at the moment. It stores all env data for years in a database. Access via web browser only though.

E.g. last two days in ISO format:




Or switch units on the fly and look at the history:

[Snore]

There are several iPhone and iPad apps that will track pressure off the Apple devices internal pressure sensor. These apps allow for the calibration of the sensor off a local airport, trending for 30 days and alarms.

[Onemoreproject]

A lot of good information has come out of this thread. My feelings about instruments and teck on a sailboat are to have then serve the greater goal of sailing, living and traveling about the world on water, without getting in the way. So, I am more motivated to have a stand alone monitor because it is the shortest path to passively monitoring barometric pressure.

Drilling down, my choices are between a MateoMan for $200.00 and a Traceable NIST calibrated one for 126.00. The major difference is that the MateoMan keeps data for 5 or 7 days and the Traceable for just 24 hours, albeit it is calibrated to NIST standards, but some sailors say it doesn't make much difference tracking weather trends is the goal. I prefer the linear line on MateoMan that shows trends although I suppose i could get used to the bar graph.

By the way, the Traceable is being re-branded and sold by different companies like Fisher Scientific and NovaTech for prices varying between 126.00 and 160.00. It may also be an updated version of the venerable Speedtech.