I do not recall any of my instructors ever explaining how to estimate visibility, and I’ve always wondered if it should be horizontal or vertical. Again, thank you for sharing your experience and knowledge.

@LakeHickoryScuba

5 ай бұрын

You are very welcome @skirblah, glad you liked the video.

Hi Bryan, why should the visibility be measured like this? You said there is the Secchi disk that measures it vertically and you keep saying "we should measure it that way" but you don't explain WHY we should measure it this way. Just because we have a tool that measures vertically is not a good reason to say it should be done like that. That is akin to saying "Here's a pot of red car paint, so all cars should be red and the manufacturer of that blue car is doing it wrong". In fact, when water clarity is a safety factor, e.g., I'm a dive master and I have to be able to see the entire group, then the entire group is about at the same depth as I am, so horizontal clarity is the thing I care about. I don't care if I can see far above or below me if there is nothing there for me to be concerned about. So, given that water clarity horizontally is what I am more interested about in scuba diving, how is the scuba industry getting it wrong by looking at horizontal clarity other than the fact that the tool to measure clarity you chose to discuss here isn't appropriate for measuring it?

@jeffconley6366

Жыл бұрын

The water clarity is going to be the same vertically or horizontally. However, how far we can see underwater is going to be affected by how much light we have at depth. Using a Secchi disk is more precise because we can measure the length of line and the sun is overhead. Of course diver's kicking up the bottom may change the turbitiy. Which will change the visibility. And I doubt you would want to take a Secchi disk and line with you to do the measurements horizontally.

@tobiashartung856

Жыл бұрын

@@jeffconley6366 I'm afraid that is not answering the question, in fact it introduces another problem. If clarity horizontally and vertically are the same, then how is the scuba industry getting it wrong in talking about it horizontally rather than vertically? That is like saying "I want to buy a Chevy Corsa" and someone replying "No, you got it all wrong, you need to buy the Vauxhall Corsa!" So, for Bryan to have a point at all in saying the scuba industry is getting it wrong, there must be a difference in measuring vertically and horizontally. If there is none, then the entire argument falls flat. If there is one, and clarity does not have this difference, then clarity is clearly not the concept we want to discuss here. So clarity and visibility are two different things (although related). In that case, talking about a measurement tool of clarity when trying to explain visibility and then claiming that the industry is getting visibility wrong because here's a tool for clarity makes no sense at all. That is like wanting to build a new steel door for my garage. I need to get the dimensions of the door but have no tape measure. Yet I have a kitchen scale. Obviously the weight of the door and the dimensions are closely related (given that steel is the material) but now Bryan's argument is "You're getting it all wrong. You don't want to know the dimensions of the door. Here's a scale, you want to know the weight!" So overall, the bottom line is that there are two possibilities. A: Visibility and clarity are the same thing. If there is then no difference between vertical and horizontal, then the claim that the scuba industry is getting it wrong is unfounded. If there is a difference, then the argument boils down to saying that the Secchi disk is the wrong measurement tool for horizontal visibility/clarity and the scuba industry still isn't getting it wrong, we just don't have a proper tool for the job. B: Visibility and clarity are not the same thing. In that case, using a tool designed to measure clarity to measure visibility is simply using the wrong tool for the job. Still, saying the scuba industry is wrong in talking about horizontal visibility is just wrong at every level. So, all in all, I am still missing the argument WHY talking about horizontal visibility is "wrong" as claimed by Bryan in this video. Everything we have discussed so far boils down to "We don't have a proper tool to measure what we are interested in. Here's the next best thing we can come up with." Therefore, I'm not saying that the Secchi disk is bad or clarity measurement is wrong. I'm saying that if there is a difference as Bryan proclaims, then we cannot use the terms interchangeably and would need a better measurement device to measure the quantity we are interested in. If however we take Bryan's point of view that clarity and the Secchi disk are proper tools for the job, then he needs to bring up a good argument WHY horizontal measurement of visibility is not what we are interested in. Frankly, I don't think that clarity and visibility are the same concept. Clarity is how far light can penetrate through water. Visibility is how far I can discern an object. As such water of the same clarity at different depths can have different visibility. Similarly, surface scatter through wave action can reduce the amount of ambient light and therefore reduce visibility. Furthermore, visibility can reduce to zero if I enter a wreck or cave and don't bring a light source even if the water has the same clarity. Similarly, full silt out at bright daylight and deep inside a cave without lights are both scenarios with the same visibility but different water clarity. So clarity and visibility are clearly linked concepts but in my opinion fundamentally different. It's like speed of a car and fuel consumption. So measuring visibility by measuring clarity is like measuring the speed of your car by looking at your mileage per gallon.

@jeffconley6366

Жыл бұрын

@@tobiashartung856 see my reply to Bryan . I miss spoke in my reply to you. You are correct clarity and visibility are not the same thing. Clarity is the quality of transparency. Which will affect visibility. And visibility is the distance one can see based on light and other conditions like turbitiy (which affects clarity). The Secchi Disk is the tool Oceanographer's use. I guess that is why Bryan said it is the correct tool. I guess you could use a Secchi disk at depth horizontally. But, would that really be practical. As we all know visibility can change quickly and be different at different depths because of light, thermoclines, particles suspended in the water and other factors.

@nathanjohnson9231

Жыл бұрын

@@jeffconley6366 Horizontal being the same as vertical may be accurate for shallower lakes, but I've had several times where the deeper I go, the more horizontal visibility I'll have do to thermoclines holding turbidity nearer the surface while I have excellent visibility at 40-60 feet. I've also had some shallow dives where visibility near the bottom is near zero due to wave / boat activity, but going just a few feet above the bottom and you're mostly clear vis. I may have 30-40 feet of horizontal visibility at 15 feet (5 feet above the bottom), but vertically it would measure 15 feet because of the low lying turbidity.

@tobiashartung856

Жыл бұрын

@@jeffconley6366 Fair enough. I guess we basically agree then. I completely agree with you that the Secchi disk could actually be used at depth horizontally and it would give a good measurement, but practicality is not the word of choice here either.

Bryan just described how Oceanographer 's measure water clarity. What we call visibility. Using a Secchi disk is more exact than guestimating while we are underwater looking horizontally.

@LakeHickoryScuba

Жыл бұрын

Hello Jeff Conley, you nailed it. We try our best to give the most accurate measurement, than a simple guess. For the average diver it probably doesn't really matter, but for us it does. Its also easier to walkout to the end of the dock to get a measurement, then to spend time diving the entire lake, developing an average horizontal range with all the other variables added in. We have some amazing places to dive here on the lake with phenomenal visibility, but only in the winter time, and then other areas of the lake are phenomenal but only during the summer time. So if we stated the current visibility is 25 feet, and a diver up the lake jumped in and couldn't see but 5 feet, then it would seem as if we had an inaccurate measurement. Thus, we would have to get an average range based on the entire lake. By using a Secchi Disk on site, we can get a more accurate measurement at that given site, from the surface, without the need to get wet for the measurement.

Very interesting video... Can I ask what deepest part of Lake Hickory is?

@LakeHickoryScuba

Жыл бұрын

Hello HobbyMan UK, the deepest part of our lake is 100 feet when it is at full pond.

@JURASSICDIVERUK

Жыл бұрын

@@LakeHickoryScuba thanks for the reply. Look forward to seeing your next video

My boys and I went to our local lake, and I must say it broke my heart to see the amount of trash we seen. Disappointed is not strong enough to describe what we seen. It was like diving in a flooded dumpster which we did pick up all we could but one of my boys got tangled in an old trot line. Got him loose and called the dive. Needless to say and unfortunately we WILL not be returning, I know that sounds horrible on my part but I am not putting myself and my sons at risk. Now, to all non divers Please.... Please do not despose of your trash overboard !!! We got our open water recently and was exploring different bodies of waters. Byran, yall have done a great job at Lake Hickory by what I can see and Iam embrassed for the North Texas area.

@LakeHickoryScuba

Жыл бұрын

Hello jackjackattack, pollution exist in every body of water. great job on picking up what you could. If more divers did this, we could make a change.

@jackjackattack9137

Жыл бұрын

@@LakeHickoryScuba Yes sir, basically your advise helped us. Being I equipped us with EMT scissors which are cheaper than d knifes. So, thank you !!! And yes there was some panic and our next class will be rescue.