Litres, Metres and Bar
American divers diving in Australia can become somewhat confused because we use the metric system. Instead of measuring depth in feet, we measure it in metres. Pressure is measured in bar, weight is measured in kilograms, and tank size (we call them cylinders) is measured in litres.
Of course we can't forget temperature. As far as Melbourne divers are concerned, water temperature in the summer gets to 20 degrees the way we measure it. Burrr that's cold, isn't it?
Imagine a group of American divers exchanging confused looks at the beginning of their first Australian dive briefing. Their dive master says, "We'll descend to 30 metres, explore the wreck until we reach 80 bar, and return to the boat after a three minute safety stop at five metres. Don't forget to take a few kilograms off your weight belt since we won't be using wet suits, after all the water is a nice warm 26 degrees."
If you were one of those being briefed, would you be confused? One of the most important things you learned while getting certified was not to panic. Don't do it now either. This stuff isn't that hard, even if you flunked high school math. After reading this article you'll be able to work through it.
Let's take a look at each of these goofy measurements without going into all the decimal points and other boring stuff. By leaving out the math, you won't get bored. If you're a tech diver and want to know how to figure things out down to the last square cubed decimal power to the Y factor, you're reading the wrong web page.
Litres
Take a look in your refrigerator at that large plastic bottle of soda. The label says it holds 68 US fluid ounces, or 2 litres. If it were a scuba tank, you'd be looking at a 2 litre scuba tank, which would be about the size of a very, very small pony bottle. Not very confusing huh?
Unless you're a tech-diver, you're probably used to diving aluminium 80s. You may have a few in your hall closet with out of date VIP stickers on them. The Australian equivalents (as far as capacity in a basic sense is concerned) to your beloved 80s, are 10.5 litre tanks. Of course the 10.5 litre Australian tanks are typically made of steel, so they are lighter than aluminium tanks, even though they are shorter than 80s.
If you're a tech diver with a set of double 100s, you can store 12 litres of coffee in each tank for those late night Flipper or Sea Hunt reruns.
The bottom line about tank size is this: in Australian diving standards, scuba tanks are measured by the volume of water they can hold in litres.
As a better guide, the following table gives you the dimensions and properties of the typical range of steel tanks, plus the an aluminium 80, as used in Australia. The steel tanks all have a rated fill pressure of 232 bar (3,365 psi). The aluminiun 80 has a rated fill pressure of 207 bar (3,002 psi).
TANK DETAILS | ||||||||
---|---|---|---|---|---|---|---|---|
Water Cap. | Tare Weight | Len. | Dia. | Buoyancy | ||||
Empty | Full | |||||||
25 cf | 3 litres 101 US fl oz | 3.4 kg 7.5 lbs | 500 mm 19.7 in | 100 mm 3.9 in | -0.5 kg -1.1 lbs | -1.25 kg -2.8 lbs | ||
40 cf | 5 litres 169 US fl oz | 5.8 kg 12.8 lbs | 460 mm 18.1 in | 140 mm 5.5 in | -0.5 kg -1.1 lbs | -2.0 kg -4.4 lbs | ||
55 cf | 7 litres 237 US fl oz | 7.6 kg 16.8 lbs | 605 mm 23.8 in | 140 mm 5.5 in | -1.0 kg -2.2 lbs | -3.0 kg -6.6 lbs | ||
75 cf | 9 litres 304 US fl oz | 10.4 kg 22.9 lbs | 495 mm 19.5 in | 178 mm 7 in | -1.5 kg -3.3 lbs | -4.0 kg -8.8 lbs | ||
80 cf Ali | 11.1 litres 375 US fl oz | 14.3 kg 31.6 lbs | 654 mm 25.8 in | 184.2 mm 7.25 in | +1.9 kg +4.1 lbs | -0.8 kg -1.7 lbs | ||
85 cf | 10.5 litres 355 US fl oz | 11.3 kg 24.9 lbs | 560 mm 22 in | 178 mm 7 in | -1.0 kg -2.2 lbs | -4.0 kg -8.8 lbs | ||
100 cf standard | 12.2 litres 413 US fl oz | 12.9 kg 28.4 lbs | 625 mm 24.6 in | 178 mm 7 in | -0.75 kg -1.7 lbs | -4.25 kg -9.4 lbs | ||
100 cf compact | 12.2 litres 413 US fl oz | 14.2 kg 31.3 lbs | 515 mm 20.3 in | 204 mm 8 in | -1.5 kg -3.3 lbs | -5.0 kg -11 lbs | ||
125 cf | 15 litres 507 US fl oz | 16.5 kg 36.4 lbs | 610 mm 24 in | 204 mm 8 in | -1.0 kg -2.2 lbs | -5.25 kg -11.6 lbs | ||
150 cf | 18 litres 609 US fl oz | 22.4 kg 49.4 lbs | 715 mm 28.1 in | 204 mm 8 in | -0.75 kg -1.7 lbs | -5.75 kg -12.7 lbs |
Metres
A metre is 3.28 feet. Why? Well that's another story. For now, just accept it is.
Why should you care? Depth descriptions of dive sites given during dive briefings in Australia, are given in metres. If you are renting gear, your rented depth gauge or dive computer will tell you that you're at 18 metres instead of 60 feet deep.
Unless you have a waterproof calculator, you may want to write a metre to feet conversion table on the back of your slate. After all, you'll need something to do on the bus trip out to look at those kangaroos in the bush, just in case you decide to spend the day not diving. Or you can use this one.
DEPTH | ||
---|---|---|
Metres | Feet | Used for... |
3 metres | 10 feet | Safety Stop |
5 metres | 15 feet | Safety Stop |
18 metres | 60 feet | Open Water depth limit |
30 metres | 100 feet | Advanced Open Water depth limit |
40 metres | 130 feet | Recreational Diving depth limit |
Bar
Bar is the way Australians measure pressure, as well as a place we go when the weather is too bad to go diving.
If you want to get technical about it (without wearing doubles that is), 1 bar equals 14.5 psi. So if you take a 10.5 litre tank and fill it to 232 bar, you'll have about 85 cubic feet of air at 3365 psi. Almost like an 80. Get it?
Most Australian dive operators will insist that you are back on board the boat with at least 50 bar (725 pounds per square inch) in your tank. Luckily for you, most Australian submersible pressure gauges (SPGs) have the red warning block between zero and 50 bar, and we all know why.
Weight a Minute
Did you know that a 15 kilogram weight belt will send you to the bottom faster than one weighing 20 pounds? You should, because when the nice Australian dive master asks you how much weight you'll need when picking out a rental weight belt, you could become an anchor instead of a diver if you don't.
A kilogram is 2.2 pounds. A good rule here is to divide what you wear back home in half. That's how many kilograms you'll need, as long as you're wearing the same thickness of wet suit you normally dive.
Where's the Ice?
"The dive master says the water is 16 degrees, shouldn't I rent a dry suit?"
No, not at all. That was 16 degrees Celsius. The water is really 61 degrees Fahrenheit. Temperature conversion requires a calculator unless of course you're a math wiz. To save time and brainpower, take a peek at the conversation table below. It covers most temperature ranges for recreational diving.
TEMPERATURE | |
---|---|
Fahrenheit °F | Celsius °C |
40 °F | 4.4 °C |
50 °F | 10 °C |
60 °F | 15.5 °C |
70 °F | 21 °C |
80 °F | 26 °C |
So What Else is Different?
Remember those short scuba tanks? They're not only different because they're short. Put a DIN valve on top of the tank, and watch the American diver try to figure out how to attach his or her regulator.
Actually, it not so bad. Unlike the Europeans, most Australian dive operators use DIN/K cylinder valves. These valves are converted from Yoke to DIN by removing an insert. Most Australian dive operators will have the tanks they hire for recreational diving configured as Yoke, i.e. with the valve insert in. Those Australian dive operators that use DIN valves will be easily able to put the insert back in to convert it back to Yoke. So if you're bringing along your own Yoke or DIN regs, it shouldn't be a problem.
We talked about the temperature in the last section. Most Melbourne dive spots require thick (5 mm or 7 mm) wet suits and hoods Not something many "tropical resort divers" are accustomed to.
The quality of hire gear will be as good, or better, than you're used to. However, you may save a dive or two by calling ahead and asking what brands and equipment configuration a dive operation uses as rental gear. In our case, see Scuba Equipment Rental.
When in Rome?
You know the saying, and it's true when it comes to diving too. While you're on the phone to a dive operator asking about their equipment, ask about their dive procedures as well. Make sure the methods used, and sites visited, are within your skill level.
Do not be afraid to ask for help or further explanation of a procedure from a dive master or instructor, and don't be afraid to cancel a dive if you're not sure it's for you. Shop around until you find a dive operation running dives that are right for you. If you have a buddy, talk it over with him or her. If one of you doesn't want to go, don't go.
Speaking of Your Buddy?
If you left your dog and favourite dive buddy at home to take care of the house, you'll obviously be paired up with someone you've never dived with before, unless one of those really neat coincidences occur. Thanks to the popularity of the huge US based dive certification organisations, there's a good chance you may end up diving with someone who has been trained to dive the same way you were. But you're not always that lucky.
Find out who you'll be diving with before the dive, and talk to that person about his or her skill level, and expectations for the dive. Talk about emergency procedures, and make a dive plan you both understand and agree to.
Speaking of Talking
Most Australian dive organisations have dive masters and instructors who speak Strine. That's the English language as spoken by Australians with their Australian accent. Some may speak other languages as well.
Dive briefings are important, but only if you can understand what is being said. If you don't understand something, ask. If you don't agree with something, please raise your concerns.
So there you have it. Once you tame your litres, metres, and bars you'll be ready to dive anywhere.
Safety in Diving
Diving Tips
- If you require the services of an instructor or dive master to go with you on a dive, then ask to make sure this is included.
- Inspect equipment and become familiar with it (even if it means a pool or shore dive first).
- Review dive procedures with a dive master before signing up for a dive.
- Become familiar with your buddy and his or her dive skills and expectations.
- You've heard it before — Plan your dive, dive your plan.
- Inspect your rental gear before leaving the dive shop.
- Have fun. Make new friends (dive buddies).
Book your Discover Local Diving Experience now! It includes a Dive Professional supervised dive in an area (normally a local pier) on the Mornington Peninsula.
We will run with only one diver booking for just one guided dive, but we will accept up to four (4) people for a guided dive, and do up to three guided dives for the day. The third dive must be on the same day and at the same dive site as the second dive booking.
For more information, please about the guided dive experience, please see Guided Dives and FAQs About Melbourne Diving.