Davis VP2 - add ons

[steve]

Besides, if the info is not accurate, who will be kidding who? I just wonger how many Vantage Pro 2 stations throughout the world are fixed to a pole on Joe Blog's privy roof and is subjected to all sorts erroneous readings but are added to the NOAA yearly statistics. Over the course of time the figures will err greatly and show a false picture of what the weather is realy doing.

Absolutely. Even some 'official' stations, while their equipment may be accurate and calibrated properly, seem to have their equipment sited in some very odd places, so how can you compare their readings with somewhere else? I've always believed that you can only ever compare your readings with your own readings.

[Paul C]

WOW - I have now found the slide rule I didnt realise I had !!

I bought a Negretti and Zambra Pocket Whirling Hygrometer off ebay a few years ago. I have just looked in the case and inside is a plastic slide rule. Its calibrated in Farenheit though, however it only works out %humidity and not any dewpoint figure.

[Paul C]

WOW - I have now found the slide rule I didnt realise I had !!

I bought a Negretti and Zambra Pocket Whirling Hygrometer off ebay a few years ago. I have just looked in the case and inside is a plastic slide rule. Its calibrated in Farenheit though, however it only works out %humidity and not any dewpoint figure.

[hailstone]

Beteljuice,
It is not MY standard that I am aiming for but the standard as laid down by the WMO. It is Davis who is unfortunately throwing a spanner in the works and as Skyview are now aware of, they are "a law unto themselves".
I don't quite get what your point is when you say about my ISS measuring mm yet giving readings which appears to be in inches. I only know that all the set up is in mm's and I may be as much as 5mm shy on the total per 25 mm of rain. A 5mm short measure metric gives a 0.2 inches. i.e. 1/5 of an inch reading Imperial. Resetting all the settings to calculate the rainfall in inches will still give me a 1/5 short measure because the fault is on the balance of the buckets and not the mathamatics and also inches are not as set down by WMO. Uncle Sam is ruling all the world ( or trying to ).
The Davis bumff tells me I can get my Latitude and Longitude from Google Earth. It did not come as a shock to me when there was all those incidents of Blue on Blue during the start of the Iraqi war. Their sat navs have moved the Grenwich Meridion 276 yards East of true Zero Meridion.
Pleased you have had a nice surprise Paul and thanks for the pointer for a new slide rule from Paint Test Equipment. I will give them a buzz come Monday.
Steve, I am so pleased you agree with accuracy being the point of collecting weather data. Davis can make their ISS with deadly accuracy but if the siting does not conform to the stringent regulations required world wide, you might as well try and measure your treasured Scotch mist.

Thanks again to one and all and let nothing you dismay.

Hailstone.

[beteljuice]

I don't quite get what your point is when you say about my ISS measuring mm yet giving readings which appears to be in inches. I only know that all the set up is in mm's and I may be as much as 5mm shy on the total per 25 mm of rain.

That happens to be the difference (if things were perfect) of in => mm counterbalance modification.

10 clicks x 0.1in = 1" = 25.4mm
10 clicks x 0.2mm = 20mm

Difference = -5.4mm !

So, if you remove the mm rainbucket modification, and keep the units as mm, it should be pretty much correct.

[hailstone]

Gotcha!
I will give it a try. It makes sense to me now that you have explained it that way. By taking off the mm adaptor the software may be fooled into still reading metric when in fact the reading is more accurate without the plastic widget.
You know Beteljuice, I would dearly like to have proof if Davis has just fobbed off Comtinental users by saying the software is measuring mm's when in fact, like their sunshine hours, it doing nothing of the kind.
Trouble is, I will now have to hang about till a half descent shower comes my way. It is only after a good continuous spell of rain that I would be able to correlate the figures for all three rain guages.
In the past I even double checked to see if I had the adaptor the right way up because it's centre of gravity is not symmetrical with the spindle.
I will let you know as soon as I have some figures to work on.
Cheers and beers.
Hailstone.

[hailstone]

Paul,
I forgot it is a bank holiday weekend so I logged onto the company you gave me who supply slide rules for Dew Point calculations.
I think both the Inland Revenue and the Fruad Squad aught to look into this company.
The Vat requested on £25 is £5-25p, the Post and Packing is £10 Totaling £40-25p.
Hailstone.

[daj]

The Vat requested on £25 is £5-25p, the Post and Packing is £10 Totaling £40-25p.

it's £25 + £10postage =£35 + VAT @ 15% (£5.25). Total £40.25

No need for the fraud squad other than perhaps it being overpriced!

[hailstone]

O Kaaaaay David.
The carriage on the Vantage Pro was only £5-25p and that was with a next day guaranteed delivery.
The weight of that package was around 7lbs and in a fair size box.
The slide rule I presume could be slipped in your top pocket. Timewise it would not take anymore than 2 minutes to pack in a Jiffy bag.
Hailstone.

[steve]

As David said - overpriced.

[hailstone]

Yes I agree Steve, but the Inland Revenue is gaining also by people being requested to pay 15% Vat on the postage and packing of £10.
Anyway, I will stick to the job in hand and try and make sense of the Pro 2 rain guage.
I took the widget out last night and so far the La Crosse has recorded 0.58 mm with the Davis-0.4 mm. and the Snowdon-0.6 mm.If only another 0.02 mm fell and the Davis clocked up 0.6mm all would be well (I think)
Hailstone.

[daj]

I know I should get out more.....but......The VAT man is quite clear on postage and VAT....if the goods are sent using the RoyalMail then postage is VAT exempt. If goods are dispatched using any other method then VAT at the standard rate must be applied.

For a good read check out HMRC Reference:Notice 700/24 (April 2003)

Clearly this is only relevant to goods bought in the UK

[hailstone]

OK so I was wrong on that score but can anyone help me out by explaining the following.

Rainfall measured by Snowdon Rain Gauge over 24 hours. 31.6 mm.
Ditto do with La Crosse rain Gauge Ditto 31.9 mm.
Ditto do with Davis Vantage Pro 2 (minus widget) 22.8 mm.

Hailstone.

[beteljuice]

So you seem to still have the same amount of error ?

I can't remember if you said you were working wireless or cabled - regardless, this would seem to a base unit error.

Do not pass Go - return it !

[hailstone]

I am completely lost. It is a wireless job but appart from the bare-earth prob recording a one off figure of -6.2 at three o'clock in the morning (probably RF interference)the ISS is fine. There is always spider's webs on the out side of the collector but nothing inside can explain the reluctance of the bucket to tip if this is the cause. The outlet from the rain collector is clear and free from leaves etc. The bucket is free to move OK, so much so that when I took the rain collector off one day in a light breeze, the buckets rocked so much the Console scrolled "It is raining cats and dogs". Davis has a sense of humour at least.
I still think the problem is in the software but I am no expert in that dept. Weatherlink is the up to date version also.
If anyone knows the volume of H2O Davis uses to callibrate say 1 inch of rain then please let me know, I could then check this out for myself. La Crosse pubishes their test griff and you can adjust the software to compensate any error. No such facility from Davis I'm afraid.
Hailstone.