We have a quick tip today about cleaning O-rings.

It can be very easy for dirt and lint to hide on O-rings. The grease practically acts as a magnet, letting dirt easily stick. If you’re not careful, a few well-placed pieces could even compromise the seal on your equipment—a costly oversight.

To minimize these chances, try cleaning your O-rings on a white (or light-colored) surface. The white will contrast with (most) dirt, making it easier to identify and remove.

Click to enlarge
This picture shows the same O-ring, with lint, on a white surface and a wooden tabletop. While difficult to see on either, the dirty is slightly more visible with the white background. This tabletop is fairly light, so the problem gets even worse with darker surfaces.

One of the first things you notice as a new scuba diver is the surprising lack of color. Discovery Channel specials and magazine layouts have brilliant colors. Where’d they all go?

Don’t feel ripped off. The fact is, water absorbs light rapidly. So rapidly, that after only 300 ft (80 m), no visible light remains. This is far deeper than you’ll ever go, but this absorption is very important at all depths.

The visible light spectrum can be broken up into the familiar constituent colors (for example, see the too-familiar picture of Newton with a prism). From least to highest energy, red, orange, yellow, green, blue, and violet. This order is important, because it is the lowest energy colors that are absorbed first in water. This chart below shows the depths at which different colors are absorbed. These are approximate, as water clarity and turbidity affect color absorption.

What is doing the absorbing exactly? All water contains microscopic particles. Light strikes these particles and scatters, with some of the light absorbed. What remains is what color you see. As the light travels farther, only blue light remains, with it eventually being absorbed as well¹. Of course, flashlights reintroduce “white” light, which contains the entire spectrum, making all colors visible again.

To illustrate, I’ve recreated how some common items would look at different depths.

Notice how the red is removed from the orange, leaving a little color while the blue text is unaffected.

1. Different particles scatter light differently, so some water appears more green than blue.

Usually referred to as a “schoolmaster”, this fish is part of the snapper family and could also be referred to as a “schoolmaster snapper.”

Physical description

Schoolmaster can reach lengths up to 24 inches (60 cm), but are common around 12 inches (35 cm).

Schoolmasters are most often recognized by two attributes. First, they have a sharply pointed snout. Second, they have bright yellow fins, which include caudal, pectoral, pelvic, dorsal, and anal.

Sometimes you will also see light vertical bands along their body, as in the schoolmaster pictured here.

Geography and habitat

Schoolmaster snapper are found all along the western Atlantic down to South America, from Massachusetts to Brazil.

You’ll find them in clear, warm water, usually over coral reefs. They usually maintain a short distance above the sea floor.

Unlike most fish we cover, schoolmasters are often found in groups. The size of these groups can range from just a few fish up to a few dozen.

Further reading

Wikipedia
FishBase.org
Reef Guide

The other day we talked about cycling wetsuits to give new life to old wetsuits. I briefly mentioned throwing out those super-old wetsuits when they get replaced by old wetsuits.

I was thinking about it, and maybe you don’t have to throw them out after all. Here are three ideas to consider before throwing it away:

• “Recycle it.” Before throwing it away, consider donating it for recycling. This can be something like Rip Curl’s Project Resurrection, where old neoprene is recycled, or something like A Warm Current (website currently down), who take old gear for kids.
• Use it for patches. While a few key areas may be worn out or torn, much of the old wetsuit probably has usable neoprene. Keep the suit around and cut it up for use as a patch when necessary. We’ll cover patching wetsuits in a future article.
• Make something out of it. A lot of things are made out of neoprene. For the artistically inclined, cut up the old wetsuit and make yourself something like a cellphone, iPod, or even a laptop case. Get creative!

I think at least one of these ideas should appeal to everyone. There’s no point dumping neoprene in a landfill, especially when it could have new life in several different ways.

We’ve got a quick update today with a few links of interest.

Boots n’ All travel website has a list of 7 unexpected dive spots around the world. I would argue that Egypt isn’t really that unexpected, but the rest are interesting.

Online scuba magazine Aquaviews has two articles on the best subjects for underwater macro photography with a follow-up of more macro worthy subjects underwater. I can’t say there’s really that much new here, but it’s a quick read with some inspiring photos.

See you tomorrow.

There’s something to be said for shore diving. No boats to wait for, no people to annoy you—you dive when and where you want. Even places you wouldn’t expect (like New York and New Jersey) can have decent shore diving.

If you spend any time reading about shore diving, either from books or the internet, you’re bound to come across the term slack tide, or sometimes, slack water. Slack tide refers to the time between high and low tides, when the tide is changing. That means there are four a day in most places.

During this time the water is relatively calm, because you don’t have excess water rushing away (low tide) or toward (high tide) the coast. This makes it particularly significant to shore divers. In many places, slack tide is the only safe time to scuba dive. Diving any other time and either you can’t enter the water (high tide) or the water will quickly carry you to sea (low tide).

When shore diving a new spot, read up or talk to people and find out if a slack tide entry is considered a must. If it’s not a must, it often turns what would otherwise be an advanced dive with strong current into an easy dive that could even be used for beginner’s certification.

A downside to slack tide is visibility. Calm water means there’s nothing to move particle matter in the water and visibility tends to go down. If you have the option, weigh that into your next shore dive scheduling.

Many websites and weather reporting services give the times of the daily tides. They are very predictable and can be calculated far in advance. Search for your location and terms like “tide tables” to find them.

The day will come. Your brand new, off-the-rack wetsuit will one day just not keep you that warm anymore. It’s time to buy a new one. Don’t feel bad, you got a good 4-5 years of diving out of it; the investment has been well worth it. Besides, a new wetsuit won’t set you back that much.

Just one thing remains: what do you do with the old wetsuit? Structurally it’s still in decent shape, so it’s a shame to throw it away. The good news is there’s a reason to hold on to it. Keep the old wetsuit, and use it for situations where it’s warm and the poor insulation won’t make a difference. Things like training in a chlorinated pool or shore diving in very warm water are perfect.

There are two benefits from keeping an old wetsuit in the closet:

1. It extends the life of your new wetsuit. By not using your new wetsuit in the pool, you save it from some harsh chemicals that will age it faster. Ditto for the wear and tear that comes any time you wear a wetsuit.
2. It extends the life of your old wetsuit. Finding new uses for old things makes you feel good. You’re keeping your neoprene knickers out of a landfill just a little bit longer.

Eventually it will get so old that it’s not even appropriate for a swimming pool. By this point you should’ve gotten a long life out of the wetsuit, so you can throw it away with peace of mind. You may even be due for yet another new wetsuit, so you can continue this cycle indefinitely.

Today’s fish is a member of the infamous scorpionfish family.

Physical description

Spotted scorpionfish are large for their family. They average around 12 inches (35 cm) long, with some males reaching 18 in (45 cm) in length.

They have wide, fan-like pectoral fins as well as dorsal spines that make this a formidable looking fish. The fleshy plumes covering their eyes give them the appearance of a grumpy old man.

Spotted scorpionfish usually have a reddish color. Their pectoral fins have a combination of white stripes and spots, hence the name. The tails also have three white stripes.

You’d think all of this would make the spotted scorpionfish fairly distinctive, but the truth is they are not always easy to spot, for several reasons. First, they are almost always stationary on the ocean bottom. When they come to rest, they stir up silt which settles along their body, effectively disguising them.

Second, their red-rust hue becomes grey even in relatively shallow water. Lastly, their recognizable striped fins are only visible while they are swimming (or threatened).

Nevertheless, once you learn to recognize them, you will start spotting them everywhere.

Geography and habitat

Spotted scorpionfish are found all along the western Atlantic down to South America, as well as in the Pacific from Baja California down to The Galapagos. I believe the western Pacific even has a variety.

These fish are found on the sea bottom or resting on rocks. Often this is under coral or outcroppings, so you may have to look around to find them.

Like most scorpionfish, the spotted variety is a loner.

Venom

Spotted scorpionfish are venomous, like all its cousins. The dorsal spines contain the venom, although it is only used for self-defense. Keep a sharp eye if touching the sea bottom so that you’re not getting an (un)healthy dose of scorpionfish venom!

Further reading

Marine Bio
Living Reefs
Ocean Oasis Field Guide