Barograph features

[Lars_L]

I am about to buy a barograph. I do not have any network aboard. I have a plotter program in the computer and my AIS are connected to that.

I want the barograph to help me predict the weather. There exists a lot of barographs on the market, but what features do I have use of? When I know that, it will be much easier for me to find the instrument.

Some features I believe that the barograph needs is:
Be able to work alone. (Maybe power from the boat).
Take very little power. 2.4 W is 0.2 A and in 24 hour will that be 4.8 Ah. That’s too much.
Have a display that shows information.
But what info?
The air pressure right now.
The change of the air pressure the last hour. In that enough with a symbol or shall there be a number i.e. -98 mbar/h?
Is there any need of showing what the change were the hour before?
Or the hours or days before that?
How accurate do it need to bee? 1 mbar?
How often do it need to measure the pressure?
If I have an accuracy of 0.02 mbar, and read the pressure 10 times per hour, I can show the pressure change per hour already after 6 minutes. Would that be useful?

[Paul L]

I use this one. It uses millamps of power.

NAVTEX/WEATHER: NASA Marine Instruments

[conachair]

I've had one of these for years, more than enough. Records pressure every hour for the previous 24.

[Lars_L]

I can see the trend on the graph, but is that precise enough to make any conclusions?

[conachair]

Originally Posted by Lars_L

I can see the trend on the graph, but is that precise enough to make any conclusions?

1 reading per hour is plenty. The graph gives you 24H¦12H¦6H¦3H¦1H¦0H which is good for a glance to see what's been going on but you can scoll through the past 24 hour by hour as well.

[Paul L]

Originally Posted by Lars_L

I can see the trend on the graph, but is that precise enough to make any conclusions?

The met service has a lot more info than the bar graph and they don't do that great. If you are in the mid-latitudes it is likely to be an interesting additional piece of info for you. If you are in the tropics then probably less so.

[UNCIVILIZED]

Ideally, you want a unit which measures down to fractions of a mb. And records same, over the course of several days. With the ability to pull up measurements on spans of time for anything from a few hours, to several days.

Plus, & this is key. You want a unit which has alarms which you can set to go off when the air pressure changes by X amount, in Y span of time.
The user settable parts being, X, & Y.

Also, you obviously want an old fashioned barometer. And for the on watch person, including when you're lounging on the hook, logs the reading into your ship's log every hour on the hour.

And a watch with a built in barometer & barograph is a BIG help. You'll become Much more in tune with the weather after you've worn one for a bit.

I'd also recommend a small ship's weather station. Even if it's as simple as a mid-level Kestrel unit.
They have; temp graphs, barographs, wet & dry bulb sensors so as to monitor humidity, & dew point, plus wind meters (with graphing & recording), & more. For pretty reasonable prices. Although there are definitly perks to having sturdier, built in/purpose built units.

Although if you have a decent, built in, instruments suite onboard, you can often configure them to record all of this data too.

But, bottom line: Definitely get the watch with the built in baro/barograph.

[Paul L]

Originally Posted by UNCIVILIZED

....
But, bottom line: Definitely get the watch with the built in baro/barograph.

Which one do you like?

[monte]

This is the one to buy

http://www.uship.fr/barometre-marine..._fr_37589.html
http://www.delite.dk/pics/a4000.2-no...uctions-uk.pdf

[UNCIVILIZED]

Originally Posted by Paul L

Which one do you like?

I had a Casio for quite a while, which I loved. But now, barograph watches are so common, I'd say to choose one based on it having the features which you like the most.
That, & that it has buttons which are difficult to accidentally get depressed.

Also, many sporting watches, nowadays, have the stupid setup, where you have to send if back to the manufacturer in order to get a new band installed. Something of which I'm Not a fan.
Not that many watch bands wear out quickly anymore. But when I find a watch that I like, I tend to keep it for many, many years (sometimes several decades). Thus the comment.

[oceansoul]

In our yacht we use this barometer. It works in an NMEA 2000 network.


Data from the barometer can be displayed on chartplotters, digital navigation instruments.
The device takes a very little power: consumption current of this barometer is 24mA.

[aluijten]

Originally Posted by Paul L

I use this one. It uses millamps of power.

NAVTEX/WEATHER: NASA Marine Instruments

I have the same. Works pretty well. It can be calibrated and uses very little power. Price is not too bad as well. It should also be able to process the wind-data from a NMEA source, but I have not managed to get that working.

[HappyMdRSailor]

Welcome to CF oceansoul !

[oceansoul]

Originally Posted by HappyMdRSailor

Welcome to CF oceansoul !

Thanks!

[barnakiel]

We use a plain mechanical device and I take note down to my book.

Great device in mid latitudes but more difficult to interpret in the tropics. Still well worth having as it gives you this one more input to draw your weather guesses from.

Plastimo EUR 100, cheaper from other makers (e.g. in some Casio watches).

PS Get a model that shows the number, not just the graph.

PS2 Models that graph it out for you are very nice provided they are of the more advanced style. Cheap six back bar periods alone are ...

b.