Visibility

[mccabejc]

I posted something a week ago on visibility, but here's something more concrete to determine how folks judge viz. Attached is a photo (thanks to divinman) of some kelp. Please ignore the horizontal vs. vertical visibility argument, and vote for A, B, or C, which are the points at which you would measure the visibility in this situation.

At point A you can clearly see detail of the kelp leaves. At B you can see only the outline. And at C you can barely see outlines.

 

[String]

Definately C for me.

I go by outlines, if i cant see the defined outline of something i dont class it as "seen"

 

[Squalus]

I have always used the furthest object away to judge distance.

 

[brian d]

I would say "c" the farthest you can make out "somewhat" an object.

 

[wcl]

C for me.

Locally diving in Lake Michigan and IL quarries, if I can see it at all, I'm happy! There have been days I could not see my hand if I extended my arm all the way ...

Cheers,
Walter

 

[mccabejc]

In recreational diving, one of the main purposes is to see stuff, no? If you can only make out a dark shape, why would you consider it as "seen"? For example, if you see a dark blob in the distance, and can't tell whether it is a Sargo or Garibaldi, can you really say you "saw" the fish?

 

[MSilvia]

In recreational diving, one of the main purposes is to see stuff, no? If you can only make out a dark shape, why would you consider it as "seen"? For example, if you see a dark blob in the distance, and can't tell whether it is a Sargo or Garibaldi, can you really say you "saw" the fish?

For some recreational divers, this may be true. For others of us, it's often useful to see a shape in the distance if we're using it as a landmark. For example, on a shipwreck in low visibility, seeing the outline of a structure can let you know your location on the wreck and orientation relative to the mooring line. Recreational diving isn't always about admiring the colorful fish.

 

[SuPrBuGmAn]

If I can recognize it as a fish, its good enough for me I don't necessarily have to recognize the species of fish. (C) has my vote as a rec diver. If I want more detail, I'll swim closer - if it swims off - so be it.

 

[Walter]

I can see the kelp beyond point C. My vote goes to point D.

 

[wcl]

In recreational diving, one of the main purposes is to see stuff, no? If you can only make out a dark shape, why would you consider it as "seen"? For example, if you see a dark blob in the distance, and can't tell whether it is a Sargo or Garibaldi, can you really say you "saw" the fish?

Indeed, the more seen the better, and I love what diving I have done in the Caribbean and Hawaii for spoiling me on what good vis is ...

However, much of the local diving here is wreck diving not fish watching, so if you can see enough of a shadow to orient and know something is there, you can at least swim over to it and check it out. Sure beats the couple of times we never found the silly thing at all!

I'm about to get my drysuit training and gear in large measure because some of the best vis is when it's rather nippy!

Cheers,
Walter