Scuba purchasing information

For both new and more experience divers alike there's a bewildering array of dive gear and BS to go with it available in NZ and the world. This page gives our brand of BS that I like to think is an honest opinion. If you feel I've got something wrong feel free to contact me and set me straight. You can either click on the link below to head straight to what you want to know or sbrowse on in. Good luck.

l Regulator l BCD l Gauges l Octi l Tank l Wetsuit l

Regulators. Regulators convert the high pressure air from your tank into a pressure that's consistently breathable at any depth you happen to be (within reason). The first stage (the lumpy bit that attaches to your tank valve) drops the tank pressure down to around 50 psi (11 bar). The second stage (the bit you stick in your mouth) reduces this to the surrounding ambient pressure. First stages come as either piston or diaphragm units. All regulators must have some method to increase the air pressure sent to the diver as ambient pressure increases (i.e. the deeper you go the more air pressure you'll need).Diaphragm types have a diaphragm usually under a nut on the end that transmits pressure changes to the regs workings inside. A piston reg has holes usually in the side that allow water to enter and assist the regs performance. Piston regs are either balanced, or unbalanced like the Calypso, (all diaphragm first stages are balanced). An unbalanced reg allows greater airflow when the tank is full but gets harder to breath when the tank is close to empty. This was a useful feature back before pressure gauges were invented. Balanced units allow constant airflow almost up to the last breath. Second stages can have features such as adjustment knobs found on the Delta reg that allow the diver to change the airflow while on the dive. Remember also that your regulator must deliver air to other places such as BC's and octi's so make sure there are enough low pressure ports. Return top of page.

BCD's The Buoyancy Control Device is one of the most important pieces of equipment you will own. It has a threefold function, to hold your tank in place, act as a floatation device at the surface and allow you to attain neutral buoyancy at any depth. There are many different styles of BCD on the market and you need to find one which will suit your requirements. There is no point buying the top of the line technical BC with twin tank capabilities you are tropical diving twice a year. Correct size and fit is the most important feature you need to look for in any BC. If it's too small it causes 'squeeze' making it hard to breath and if it's to big it won't hold your head above water at the surface. Try the BC on with a suit of the same thickness as the one you will dive in, inflate the device, the BC should not restrict your breathing or give you squeeze (a tightness around the chest/stomach area). Check the BCD for accessibility of straps for adjustments and the inflator hose for ease of inflation and deflation - there needs to be a clear distinction between the buttons. You will also need to consider the amount of lift your BC should provide, this will be different for various diving situations i.e. tropical diving you may only need 6 to 12 kg's lift, whereas recreational diving you may need between 10 to 20 kg's especially if you carry lots of weight on your belt. Some BCD's have all the air on the back like the Balance BCD. This is handy for wreck and cray divers as they are lower profile however some people find they get pushed on their face while on the surface. Finally, you will need to decide whether you need a weight integrated/non weight integrated BCD like the Probe. There are advantages and disadvantages for both. A fully weight integrated BCD means that you are carrying all of your weights within the vest, usually most of these will be dispersed at the bottom of your BC, in the front and sides - though some BC's do have non dumpable pockets for some weights at the back. The advantage of weight integration is that you can lose another piece of gear from your ever increasing pile of dive equipment plus it relieves strain on your back. However there are disadvantages. If you need to remove your BCD for any reason i.e. tank slipping out your wetsuit will want to pop to the surface and your BCD and of course reg system will likely head down very fast. Weight integrated systems all have a quick release function, some systems are internal yet others have external releases - this could pose safety problems if they get caught up on rocks or weeds etc. Once again you go up and everything else goes down. Don't forget if this happens you can't get down again to retrieve your gear as you have no weights. Not only are there safety issues involved there is also the compromise on the integrity of the BCD fabric plus with 12 Kg or more in your BCD plus 15Kg of tang with 5Kg of wet dive gear this is allot of weight to lift whether into a boat or onto a back. Return top of page.

Gauges/Computers Generally come in two pot (pressure and depth gauges) or three pot (includes compass) setups that connect to the high pressure port in your first stage. Two pot have pressure gauge and depth gauge or computer. Three pot adds a compass. Depth gauges should have a thicker needle that will tell you how deep you are and there should also be a thin needle that stays at the maximum depth of the dive (it must be reset to zero before each dive). Why are they staying down? you ask yourself, we have done the same dive profile yet my tables tell me to come up now yet why are they still staying down there? That's right the dilemma between tables and a dive computer. By constantly monitoring depth and bottom time your dive computer can automatically recalculate you no-decompression status, giving you longer dive times while still keeping you safely within the limits (limits vary from brand to brand, be aware that some computers are more conservative than others). Although the dive computer can not replace the brain, it can at least relieve the burden. Computers will also monitor your ascent rate, tank pressure (only for air-integrated models), log your dives and even tell you when its safe to fly. Before buying a computer - decide what features are most useful for your personal type of diving. If you are a recreational diver who has no intention of diving with mixed gases you can save $$$ by avoiding computers that do. The Vyper and Cobra are two computers that can be used for nitrox or enriched air diving. Do not get carried away with features you do not need or will never use. The most important feature is that the information that you need right away is accessible. Some computers have a one button function where the information will all appear at once, while other computers have multiple buttons. Cheaper computers like the do not give full deco information if the need arises others do. Other aspects you may wish to consider when purchasing a computer is are they user changeable batteries. If they are always carry a spare set. Whatever computer you buy -READ THE MANUAL (yes guys this means you to). Return top of page.

Octi's A good octi will show a commitment to your buddy, it will make more people want to dive with you - like a chat up line for divers. Octi's are the same as standard second stages with one minor variation, their air flow has been adjusted so that it does not free flow in the water as your primary second stage can - this makes it a little harder to breathe from yet saves you wasting your air with freeflows. Features that you need to look for in your octi are a longer hose than your second stage as it will need to reach to another diver, some bright colouring, preferably a different colour from your primary second stage - this colouring could be on the hose i.e. some octi's have a yellow hose or hose wrap, it could be on the body of the octi. Some octi's like the Aqualung LPO are designed so they can work sufficiently if put in the mouth upside down. These are usually slimmer than standard octi's like the Gamma and Titan or it could be a brightly coloured scuzz ball (the octi holder on your BCD). Return top of page.

Tanks Steel or aluminum that is the question, but not the only one, as with most things in life, with tanks, size does matter. No matter what sort of tank you buy you need to be aware that they all need testing annually, the tests alternate years between a full hydrostatic test in which your tank is pumped with water to test its pressure status and the alternate year it requires a visual inspection for cracks, rust and other unsightly nasties. Aluminum tanks have thicker walls than steel so appear a lot bigger for similar air capacities. Aluminum tanks also become more buoyant the less air they have in them, this can sometimes pose problems for new divers who haven't quite got comfortable with the weights, the five meter safety stop can quite often become a myth as you float right past it. Steel on the other hand will not affect your buoyancy at any stage of the dive as its buoyancy remains the same regardless of its air content. You can usually get away with a couple of kilo's lees on your weight belt if you use a steel tank. Tanks are available in many different sizes, the most common for aluminum are the 80 cubic foot and 95 cubic foot, while in steel they go up to 105 cubic foot and 123 cubic foot. Capacity of tanks can also be measured in Liters (the internal volume of the tank) however this isn't always accurate as fill pressure affects the tanks capacity as well. Newer divers tend to go through air a bit faster but this will usually change with more experience so don't rush out straight after your open water for the biggest tank on the market to keep up with the more experienced diver. Remember when you are buying a tank, you're the one carrying it around. Finally we come to the difference in price. Steel tanks tend to be a lot more expensive that aluminum tanks. Return top of page.

suits Made from neoprene which is the sludge that comes from oil refineries, with bubbles blown into it. Diving suits usually come in two thickness 7mm and 5mm. Most NZ divers use 7mm for the added warmth but it does require more lead on the weight belt 5mm has the advantage of being more flexible but is colder suits come as either one piece suits such as the Pro 1000 or two piece like US divers. One piece suits also known as semidry are reputed to be warmer as they have seals on the wrists, neck and ankles. This cuts down the flow of cold water through the suit. They also have the added advantage of as there's only one layer of neoprene around the body the wearer needs less weight on their belt. One piece suits do not usually have built in hoods so you will need to buy a separate one of these if you require it (in winter you will). Also available are 3mm vests with built in hoods which give added warmth all over. Two piece suits often have built in hoods and the double layer of neoprene around the trunk of the body means added warmth on deeper dives when the wetsuit is squeezed thinner by water pressure. Also frequently mentioned in today's suits is the inclusion of a titanium layer or two that 'reflect both heat and cold'. The only study done showing titanium has any noticeable increase on a divers warmth was done by the neoprene manufacturer themselves. Next time someone tells you the titanium will reflect cold ask them to see the mirror that reflects darkness. Titanium will reflect heat transferred by radiation but unfortunately the heat we loose during diving is via conduction. Place your hand on a sheet of titanium siting on a fire and see what I mean. Whether one or two piece a wetsuit must be a snug fit to work. Too loose and chilling water will flow through, too tight and you can't breath even if you can get into it. Most suits will have a little room under the arms to allow movement but the rest should be firm. Fro older divers-yes neoprene does shrink. Return top of page.

If you are considering buying dive gear, please come in and see us for a consultation we will listen and ascertain you diving level and requirements and write you a prescription for gear we think best suits you not us. Remember, our second golden rule at Orakei Dive is that most expensive is not always best (our first golden rule is take them for all you can-- only kidding, someone complained about it so I thought I'd better point out the obvious).