Any way to tell from the surface if the visibility is going to be good?

[Basking Ridge Diver]

A Secchi disk is a circular plate divided into quarters painted alternately black and white. The disk is attached to a rope and lowered into the water until it is no longer visible. Secchi disk depth, then, is a measure of water clarity.

Very interesting Tbone - although I don't personnally like the no longer visible measurement aspect - it may be subjective but I use my own measurement of when does the object become obscured so that you can no longer see characteristics rather than just a shape. I use that for my viz measurement.

 

[scoobydrew]

I find colour is a good indicator. The issue is that one size doesn't fit all so the trick is to get used to what the colour of the water equates to in visibility in your local area then eventually you'll be able to get a bit of a handle on it. For example, if you have a good day's vis then make a mental not of the colour of the water, same for a bad day.
It's by no means an exact science but it has helped me make a rough gauge in the various places I have worked.

 

[tbone1004]

the salt water one is 12" and all white, the alternating quarters is used for fresh water, although for what we do, either one will work just fine. It's the "official" measurement, that said, it is very subjective, and while that is how you find a scientific definition of the visibility, you can also just determine your threshold for comfort and use that. Knot the line every 1m or 5ft, and use that to figure out how far your "comfy" vis limit is. Oh, and I highly recommend polarized glasses for trying to get a measurement when the water is still and the sun is bright, only way to cut through the glare.

 

[tursiops]

The Secchi Disk is an old device that gives approximate results that are dependent on the sun angle, the observer, and the disk size and coloration. There is no standard, and it is not used in the science community that studioes the optical properties of water. It is a common citizen-science device, but at best is not the same as the "viz" we talk about as divers. We are mostly interested in horizontal visibility, nor vertical, so any turbidity gradients in the water make the horizontal and vertical visibility distances rather different. Divers tend to use contrast as a viz estimate: "How far away can I see something?" translates to being able to see some detail and some recognition. A fuzzy shape in the distance in not within the viz....two divers I can't tell apart is not within the viz. Lots of technical stuff is here and here and especially here, but the punch line is that a black target viewed horizontally gives a more reliable estimate than a white one viewed vertically.

 

[CuzzA]

GoPro and a rod and reel. Drop it down, pull it up, review footage and you'll know exactly what the viz is.

BTW, when planning a dive around viz, you'll find the incoming/high tide typically will have the best viz. Clean water is in the open ocean, dirty water is on shore. Of course you have to consider other environmental conditions too, like weather, currents and rain. If you had a lot of rain earlier in the week, you can bet all the runoff which includes fertilizers has made its way to the ocean and has created a phytoplankton and zooplankton bloom degrading visibility.

 

[drbill]

I can only speak for southern California and the tropical waters I dive during our harsh winters. From a boat it generally isn't that difficult to tell whether you have great visibility or not. I think back to the days when I could see the bottom in water over 100 ft deep. However, if you are in deep water it may be very difficult to judge visibility unless you have a school of fish swimming beneath you or some other reference.

 

[Hank49]

I take the boat out to the reef, 15 miles or so, pull up to the dive site, toss the anchor and look over the side. Unless it's complete mud, which is never is on the reef, I'm jumping in. Some days it's fantastic and some days it ain't. That's diving.
But a Secchi disk is a good idea for blue water diving. (free dive spearfishing) I'm an aquaculturist by trade and have used them for years.

 

[TMHeimer]

For shore diving on the East Coast a west wind is best - it seems to blow any of the "trash" and particulates out...
If you can get over the water (like an inlet wall) and drop a seashell - count how long you can see it before it disappears... Generally longer than 5 seconds is good around here... YMMV

I hear ya. I've dived in Joisey. Come to NS to ditch those particulates.....

 

[Steve_C]

Once it gets deeper than 40 ft it can be tricky. Off NC the viz can vary by depth in layers. I have stepped off the back into 2 ft of viz. Had to hunt to find the down line. Then going down the anchor line at around 30 ft the viz popped out to a nice 20-30,

I have seen the reverse several times where there is clear water, even blue on top and then part way down the viz drops. Sometimes dramatically. I have been in 40-50 ft viz and had it drop to 4 ft in about 3 ft. Both time after checking out the bottom I have gone up above the cloud bank and just floated around watching stuff swim by.

 

[Basking Ridge Diver]

I hear ya. I've dived in Joisey. Come to NS to ditch those particulates.....

Have equipment willing to travel - my family came from Newfoundland so - be careful I may take you up on it...