woensdag 27 juni 2012

2012-06-26 19:18 hbos Spotted a little white globe.

Weather : clear sky / WNW wind 2 bft / Rain  0.0 mm / 1020.9 hpa
Divers : Remko, Axel
Goal : Visibility check
Max depth : 16.7 mtrs 
Duration : 83 minutes
Air temp :  16.4 celsius
Water temp : 17.2 celsius minimum
Fish: 2 eals - 7 large perch - 1 zander on it's usual spot, clouds of shrimp, from 9 mtrs and up waterfleas.
Plants : lucious growth gutweed (darmwier) which seems to be more abundant then Elodea (Waterpest) Measured one curly pondweed = 2,60 mtrs high.
Spotted a Sinantherina which in Dutch is called Raderdiertjes. This little white globe is attached to a waterplant. I have never noticed this before in hbos. It is about 5-7 mm. See photo's which unfortunately are super sharp.
Visibility  : 5.0 mtr at 6 mtr depth at reel
Yellow viz: no readings.
Remarks : > 10 divers 
The thermocline is still at 16,5 mtr depth with a milky layer underneath it.
Since the Southwest pump started the watertemperature is pretty constant from surface to 16 mtrs depth. 
A lot of swampgas is emerging from the bottom more them usual.

dinsdag 26 juni 2012

2012-06-26 Graphics temp and viz changed!

It is more realistic to show temp at 3 mtr depth, because the minimum temperature depended on how deep we went on a particular dive.
Now you see a nicer and more steady curve.

zondag 24 juni 2012

2012-06-24 10:04 hbos Shrimpexplosion!

Weather : Overcast / SW wind 4 bft / Rain  10.0 mm / 1007.0 hpa
Divers : Mark, Axel
Goal : Visibility check + Watersample.
Max depth : 13.0 mtrs 
Duration : 61 minutes
Air temp :  13.4 celsius
Water temp : 17.6 celsius minimum
Fish: 1 eal and 1 large perch. 1 pike, clouds of shrimp young and old
Plants : lucious growth of plant. Unfortunately by the reel a lot of sponges are dislodged and lying at bottom presumably done by divers holding the reel or swimming underneath it. 
Visibility  : 6.0 mtr at 3 mtr depth / 6.0 mtr at 6 mtr depth 
Yellow viz: 8.0 mtr at 3 mtr depth / 8.0 mtr at 6 mt depth (at Paviljoen)
Remarks : > 10 divers in water doing trainings
Watersample taken at 3 and 6 mtr depth for weekly analysis.

About visibility readings:
Measurepoint for Project Baseline is located at the right outer pile of the Paviljoen at 3 and 6 meter depth. We chose this location because regardless the amount of visiting divers the visibility is almost unaffected.
Light conditions are good with a dark backround.
This is why visibility readings seem to be optimistic as apposed to the general dive area.
When yellow visibility plate fades the contrast is completely gone, diver holding plate is not visible either.
Baseline visibility meter gives an output with more contrast so you can still see diver's black suit holding the meter.
The object is identifiable.
 
What's the visibility in a swimmingpool?
During a test in the swimmingpool  the baselinemeter gave max 12 mtr while we could see divers at the other end of the pool (25 meters). This was performed by two persons to get more input. The diver holding the meter was very clearly visible. The yellow plate disappeared after about 27 mtr (taken diagonally in the pool) At that point the diver wasn't also visible anymore. In this case the yellow plate gave a more realistic reading.

Today in outdoor conditions on a rainy day without sun in hbos.
-> Baseline visibility meter shone by measure diver him/herself gives 1,5 - 2 mtr less visibilty then yellow plate without lamp. 
-> Baseline visibility meter shone by buddy holding the meter gives the same reading as yellow plate without lamp.

So which reading is correct?
Internet says;
"Visibility is generally considered to be the distance at which an object underwater can be readily identified."

Basically when contrast has completely gone as done with yellow plate, an unknown object cannot be readily identified. Coming closer about 1,5 -2 mtrs to the object, it can be identified.
Dutch waters are usually green / yellow / orange coloured and it rarely has visibilities over 12 mtr.
For Dutch waters the Baseline meter meets the criteria better then the yellow plate given the fact you're vision is not impaired or if you gave corrected glasses in your divemask.
For clear waters (regardless the colour) with visibilities over 12 mtr the Baselinemeter is (to my opinion) not suitable.


woensdag 20 juni 2012

2012-06-19 19:56 hbos

Weather : Partly Cloudy / N wind 2 bft / Rain 0 mm / 1018.0 hpa
Divers : John, Axel
Goal : Visibility check + Watersamples
Max depth : 18.2 mtrs 
Duration : 108 minutes
Air temp :  15 celsius
Water temp : 10.8 celsius minimum
Thermocline:at 16.5 mtr drop from 16.3 to 10.8 celsius
Fish: 5 eals and 2 large perch. 1 Zander, Schools of young (approx 1 cm) perch feeding on clouds of young shrimp

Plants : fresh pondweed of 1,8 mtr and higher in northwest corner. 
Visibility  : 5.0 mtr at 3 mtr depth / 5.0 mtr at 6 mtr depth 
Yellow viz: 5.0 mtr at 3 mtr depth / 5.0 mtr at 6 mt depth (at Paviljoen)
Remarks : > 10 divers in water.
Watersample taken at 3 and 6 mtr depth for weekly analysis. Due to working airpump in SW corner. NW pump is turned off. Waterfleas almost obsolete, instead large quantities of young shrimp. In dive area visibility is 3 mtr. Water is milky green. From 16.5 mtr till deeper there is a thick milky layer. Visibility there is less then 0,5 mtr. Eals have burried themselves into the mud at depth above the Thermocline. Near the piles there are huge schools of young perch. 

dinsdag 12 juni 2012

2012-06-12 20:11 hbos SW airpump working. Piona Longipalpis with eggs

Weather : Cloudy / N wind 3 bft / Rain 0 mm / 1011.2 hpa
Divers : Thijs, Axel
Goal : Visibility check + Watersamples (done by John and Mark)
Max depth : 13.9 mtrs 
Duration : 101 minutes
Air temp :  11 celsius
Water temp : 16.0 celsius minimum
Thermocline: none
Fish: About 4 eals > 5 Perch, small schools of young (approx 1 cm) perch feeding on waterfleas, 
Piona Longipalpis (Rode watermijt) laying eggs on curly pondweed. see photo's on picasa
Plants : pond weed of 1,8 mtr high in southwest corner
Visibility : 4.5 mtr at 3 mtr depth / 4.0 mtr at 6 mtr depth 
Yellow viz: 5.5 mtr at 3 mtr and 6 mtr depth (at Paviljoen)
Remarks : > 10 divers in water.
Watersample taken at 3 and 6 mtr depth for weekly analysis. Due to wiorking airpump in SW corner the airborne sediment along with massive amounts of waterfleas reduce visibility. In dive area visibility is also compromised by many divers. Many (young) shrimps which rest on waterplants. There are areas of fresh pondweed at about 6-7 mtr depth. THe airpump has a big effect now

woensdag 6 juni 2012

2012-06-05 20:03 hbos Tiny plant grows from mussel

Weather : Cloudy / SSW wind 2 bft / Rain  0 mm / 1016.2 hpa
Divers : Jack, Kacper, Axel
Goal : Visibility check + Watersamples
Max depth : 14.8 mtrs 
Duration : 94 minutes
Air temp :  12 celsius
Water temp : 15.6 celsius minimum
Thermocline: none
Fish: About 10 Conger sized eals (I lost count). > 10 Perch, small schools of young (approx 1 cm) perch feeding on waterfleas, 1 zander (alive) 1 pike,
Plants : Algea dots have completely gone at surfacelayer, only shrunk remnants of it on bottom. Some single shoots of pond weed of a meter high. One tiny plant growing from a Mussel See picasa photo's
Visibility : 8 mtr at 3 mtr depth / 7 mtr at 6 mtr depth 
Yellow viz: 10 mtr at 3 mtr and 6 mtr depth (at Paviljoen)
Remarks : 3 divers in water.
Still enormous counts of waterfleas, Dead Zander at Paviljoen at 11 mtrs.
Watersample taken at 3 and 6 mtr depth for weekly analysis.