who is right?

[rebelrph]

I want the "all knowing" folks on this board to settle an argument for me.

A friend of mine thinks/says whatever that when you enter the water that is 100' deep and you can see the bottom that means there is 100' visibility.

I think/say that visibility is stated as the distance one can see horizontally - not vertically.

Who is right?

Thanks,

todd

 

[roakey]

Strictly speaking, visibility is measured using a large black and white disk that is lowered into the water. When it disappears, the depth is recorded. It is then raised, and when it reappears the depth is recorded. The two depths are averaged and that's the visibility.

Me, I take a wild guess at the horizontal distance I can see and record that for visibility.

Roak

 

[Walter]

Horizontal and vertical visibility are often different. When referring to viz, it is horizontal visibility.

 

[Butch103]

Glad that was settled.......hehehehe...I always thought it was the horizontal at depth........So Todd...I guess your buddy buys the next round ???:boom:

 

[-=>Larry<=-]

Walter once bubbled...
Horizontal and vertical visibility are often different. When referring to viz, it is horizontal visibility.

I'll take the Sechi[sp?] disk to the Springs and get 50-60 ft. vis in water that's at best 25 feet deep!
Similarly, at Lake Travis - It's the deep water that's generally clearer,
Best to speciify vertical or horizontal! - although I seem to remember that the "istructions" aimed at somebody lowering the disk off of a boat, or similar!

 

[Scottri]

I've always measured it horizontally. To me, it's more accurate since light affects vertical vis much more. Besides, I rarely spend a dive looking up!


Scott

 

[Epinephelus]

Visibility - the visibility that counts - is how far you can see in the direction you're looking. If you're looking down at the bottom, that's the visibility in that direction. If you want to restrict "visibility" to horizintal visibility, call it horizontal visibility, or vertical for vertical or whatever. For divers it is often "how far can I get from the boat and still see it" that counts.
Bottom line - it's your logbook - put the important measurement in it.
E. itajara

 

[Uncle Pug]

with the layered viz we get here horizontal is usually a lot better than vertical... so when vertical is good it is really a treat!

Yesterday it was fun being able to hover 25' above stuff on the bottom and see it... and roll over and see the surface 50' above. No big deal to warm water folks... but up here in the PNW that's cool.

Sea Lions too.... yesterday was a good dive.

 

[ERP]

Me, I take a wild guess at the horizontal distance I can see and record that for visibility.

This is probably what most people do, it's interesting to see just how much peoples estimates vary. I've been on dives where I estimate vis at 10-15ft and my buddy's estimated at 5-6, I guess I'm just a glass half full kind of a guy, we did at least both agree that the vis was crappy.

No big deal to warm water folks... but up here in the PNW that's cool.

Yeah but all those people who dive in 100+ vis, miss out on the cool bits of low vis. Watching things materialise 20ft in front of you as you descend is cool in it's own right.
Admittedly it'd be nice to occasionally have great vis just for the contrast.

Sea Lions too.... yesterday was a good dive.

Yes it was

 

[Rooster1]

If you are in the water and you look up or down or sideways or anyways if you can see a hundred feet then you can see a hundred feet regardless of direction