How do "you" judge visibility?

[11B3Y]

Hey everyone,

I was wondering, on my logbook, I have a line for entering "visibility."

How do you measure that? Count the fin kicks of your dive buddy until he swims out of sight? Just kidding....

Just wondering how everyone did it....

Thomas

 

[Spectre]

It's all a guess. Generally what I do to start is as I'm preparing for decent, I take a look. Can I see the bottom? Well, if so, then the vis is greater than how far that initial decent is. After that I just glance around and make a guess.

Well, I've gone 20 ft from that rock... can I see that rock?

 

[Uncle Pug]

1. Shane and I separate (reluctanly) by a pre-determined distance.

2. We each shine our HID light beams to a point just where visibility begins to drop off substantially.

3. We each measure the angle off our beams to the imaginary line between our positions.

4. We consult our wetnotes for the tables that allow us to calculate the actual distance to where our beams intersect.

5. I am kidding here of course... we really get out a tape measure and....

 

[WreckWriter]

I've heard it defined as "the distance, horizontally, at which you can clearly see another diver". If very subjective though. Maybe you see better than I do? What defines clearly?

In a nutshell, just take a WAG (wild ass guess)

Tom

 

[11B3Y]

UP,

LOL. You had me going until number 3. Then a "light" went on in my head (pun intended).

Thomas

 

[Spectre]

Originally posted by Uncle Pug
4. We consult our wetnotes for the tables that allow us to calculate the actual distance to where our beams intersect.

Jeez UP. Isn't it easier to use distance reporting binoculars?

 

[danceswithoctopus]

Isn't it easier to use distance reporting binoculars?

I can't seem to get mine to work properly underwater. Maybe I shoulda got the waterproof ones?

UP's trigonometric calculations work well, but I don't like trying to use my calculator at depth (it's cold here and I've got 1/4 inch of neoprene on my fingers--tough to hit the keys).

So it all falls back on WW's method: take a WAG. (Although if you can see the bottom when you're on the surface over 20 feet, it's at least 20 feet, right?)

 

[MikeFerrara]

This is an easy one. I hold my hand out in front of me and gradually move it closer. When it comes into view I stop and estimate the distance. I then record the distance (in inches) in my log. Of course if I am unable to see my hand at all, I just write down something like POOR in the log book blank.

 

[Spectre]

Originally posted by MikeFerrara
Of course if I am unable to see my hand at all, I just write down something like POOR in the log book blank.

:rofL: We had a day that this description works perfectly! In a serious plankton bloom, trying to signal to my buddy with my hand 6 inches from his face. As I held his shoulder, I couldn't see anything past my elbow!

 

[large_diver]

Can I see my feet? If yes, vis = at least 6 feet

Vis in New England is rarely above 25 feet, normally about 15 on a good day in warmer weather.

Not much room for error....;-)