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WaScubaDude
03-06-2008, 09:19
Aside from WAG (wild ass guess) do you know good ways to determine accurate vis?

mwhities
03-06-2008, 09:23
I give my buddy the end of my line on my 100ft spool and have hime swim till I can't see him anymore. I have it marked every ten feet. If it's more than 100ft, I say the viz was 100ft+. :)

SkuaSeptember
03-06-2008, 10:46
1. count kick cycles to the furthest object I can see clearly
2. look up at dive flag or boat periodically and check depth.
If either of these two methods are applicable, the viz is great!
3. Can I see the full body length of my buddy? If yes, vis is ok
4. If #3 is no - can I see my fins? If yes, vis is marginal
5. If #4 is no - can I see my hands at arms length? If yes, vis is poor.
6. If #5 is no - can I at least see my gauges when held close? If yes, its a braille dive, but WTH I'm already wet, maybe it'll get better.
7. If #6 is no - probably gonna call the dive.

UCFKnightDiver
03-06-2008, 11:08
I just guesstimate

cmburch
03-06-2008, 12:06
As a building contractor and taking part in other recreational activities, I'm pretty good at estimating distance. I make a comparison to commonly known distances. So I also guesstimate. For example, 6' person, 8&10' sections of wood or multiples of, 25' car, 25yd pool or firing range, 50m pool, 50-75yd range, 100yd field, 1/4 mile track, etc. Also shorter lengths such as inch, centimeter, millimeter, foot, 2 foot, yard can be estimated similarly by comparison.

Visibility for me is the distance that I can I still make my buddy out - that I can recognize that he/she is actually my buddy (not a nondescript diver) or the distance that I can recognize whatever I am hunting.

Dive-aholic
03-06-2008, 12:11
Like cmburch, I'm pretty good at estimating distances by comparing known objects. My usual reference is body length of a 6' tall person.

As for what determines distance for me, if I can still see a hand signal, then that's the distance of the visibility. Once I can no longer be sure what hand signal I'm looking at, then we're out of the operational distance even though I may still be able to see the diver signaling me because at that point I'm can't respond and am no help to that diver.

CaptainRon
03-06-2008, 12:31
I just rate visibility in my log as good, fair, or poor. What I rate good in a local lake would be poor in the Cozumel so my method is all relative.

cummings66
03-06-2008, 12:45
I don't guess at it, I'll say how many feet I had because I don't believe relative is what I want to know 10 years from now. I'd like to be able to know that the new construction they did dropped vis 5 feet for example.

So, I use common things like the height of a person, or I find an object under water I am heading towards and count my kicks to get there. That tells me how far it is.

I don't use vertical measurements because they're often wrong, vis is measured horizontally. There is no guessing involved, for me at any rate.

CompuDude
03-06-2008, 12:47
I estimate the distance I can make out distinct objects.

WaScubaDude
03-21-2008, 02:00
snip....
As for what determines distance for me, if I can still see a hand signal, then that's the distance of the visibility. Once I can no longer be sure what hand signal I'm looking at, then we're out of the operational distance even though I may still be able to see the diver signaling me because at that point I'm can't respond and am no help to that diver.

This sounds great and I think should be the standard for what constitutes visability, then just have to answer the distance question.

Haven't worked out an underwater system, but in the NW forests there is some rule of thumb, seriously, You hold your thumb out at arms length, close one eye and a tree the size of your thumb is something like 1/2 mile away.

Maybe measure the distance away a 6ft upright diver would be the same height as your outheld thumb, or frammed in the thumb and finger "L". Just have to let your buddy know you don't really mean to signal him that he is a "L"ooser.

ChrisA
04-02-2008, 19:21
Aside from WAG (wild ass guess) do you know good ways to determine accurate vis?

My "short scale" is like this:
I first check is "can I see my own fins?". Then Can I see my glove if I hold my arm out in front of me. Then Can I read the gauges if I hold them close and use a light. I will report it as "glove disapears at arm's length" or "can see fin tips"

My longer scale is to notice how fae away my buddy can be without loosing him. I use body lenghts to judge feet and I'll estimate 10, 15 or 20. Past 20 it does not mater.

EuphoriaII
04-03-2008, 15:26
I usually put it in the log book as how many feet I can see. Usually judging by the height of a person averaging 6ft.

ReefHound
04-03-2008, 15:36
For those estimating it by eyeball remember to take into account that objects appear 25% larger/closer for nearby objects.

No Misses
04-03-2008, 15:52
1. count kick cycles to the furthest object I can see clearly
2. look up at dive flag or boat periodically and check depth.
If either of these two methods are applicable, the viz is great!
3. Can I see the full body length of my buddy? If yes, vis is ok
4. If #3 is no - can I see my fins? If yes, vis is marginal
5. If #4 is no - can I see my hands at arms length? If yes, vis is poor.
6. If #5 is no - can I at least see my gauges when held close? If yes, its a braille dive, but WTH I'm already wet, maybe it'll get better.
7. If #6 is no - probably gonna call the dive.

Braille Dive! :smilie39: That's a good one.

I consider it to be bad vis when I crash into the sea floor, without seeing it first.

Dive-aholic
04-09-2008, 02:03
Past 20 it does not mater.

I did a dive in Mexico last week where the visibility was about 40'. The visibility that low in that system made a big difference on the dive. We really didn't get the full picture of what that system looked like because of the milkiness of the water.

mitsuguy
04-09-2008, 07:47
Past 20 it does not mater.

I did a dive in Mexico last week where the visibility was about 40'. The visibility that low in that system made a big difference on the dive. We really didn't get the full picture of what that system looked like because of the milkiness of the water.

It is rough when you are used to 100'+ on those dives huh...

I think every dive in Jamaica and Coz last year, I wrote down 80-100+ as visibility... I clearly remember in Coz being over a group of divers that was 100' down and I could see them clearly, although they were a good distance away obviously... Jamaica was the same way, not quite as clear, but still 80+ easy... When vis is awesome like that, I don't think there is any real way to judge it...

Dive-aholic
04-10-2008, 03:31
It is rough when you are used to 100'+ on those dives huh...

LOL, it can be! Actually, I can deal with 5' of visibility, even in a cave. But when the distance between the walls of the cave is more than the visibility, it takes a little bit away from the dive.

scubasamurai
04-10-2008, 10:37
simple for me. if i can see the bottom or the wreck than great vis, but if i can't see the bottom ( talking 40-80 ft dives no wall dives before nayone comments haha) than bad vis. and really really bad vis is if you can';t see your buddy next to you!

cummings66
04-10-2008, 18:44
I have a couple times actually reached out and grabbed my buddy to see if he was still there. I call that poor vis. If I can see 5 feet that's ok vis to me.