Welcome to Our scuba diving news for April 2012.
We cant believe its April again already. Another year has passed it now time to play Songran again as things start to really heat up here in Thailand. Special feature this month takes a look at Scuba Pro Jet Fins and our scuba tips this month are on Buoyancy Trim.
Dive Centre Updates
We would like to congratulate Anj on an exception performance during her advanced Open Water course this is a picture of her with a sea cumber healing her fear of them from the first days diving 😉 Read more about advanced Openwater course here.
Check it out! A new Nudi Branch has being seen @ Pattaya Near island Koh Sak.. we are always on the look for new nudi and this month we found one.
Dive Site Review – Shark Fin Rock – Samae San Thailand
Location: Approximately 1 Km ( ½ n. mile) west of the Hardeep ship wreck lies a small rock resembling a shark fin
Conditions: During northerly winds this site is quite suitable for novice divers. Southerly winds, however, make it suitable for more experienced divers only. Visibility ranges between 5m (16ft) and 15m (50ft). Strong currents can make the site unsuitable for novice divers, although one side or the other is normally protected.
Average depth: 15m (50ft) Maximum depth: 28m (95ft)
Although at first sight Shark Fin looks to be a very small dive site, once in the water a large reef appears. On the north western side of the rock the reef close to rock is shallow,large areas of stag horns brain corals, barrel sponges and anemones are abundent.The main attraction is the South eastern side with it’s 16 m (55 ft) vertical wall almost braking the surface. The north eastern side has a single rock formation that is vertical on the west and has a large sand bank sliding down to 25 m (80ft) on the east, this is home to some large Black Spotted Sting Rays. On a good day this is easiestly the best dive site Pattaya has to offer. Marine life is plentiful and varied.
Monthly Special – Scuba Pro Jet Fins Review
These fins have a legendary reputation as being one of the best find designs ever made… why…
For starts they are heavy, stiff, and obviously made to push through water. The only part that flexes is the very end of the fin, not reinforced by a side paneling of rubber. These fins allow you to push water and therefore gives you as much thrust as your legs can provide. You will feel every movement you make with these fins.
Pros & Cons: Because the heavy stiff nature that allows you to feel every single precise movement of the fin this make specialty kicks such as frog, helicopter, back kicks exceptionally accurate and easy.
You get so much control with these sets of fins. With these fins I usually frog kick, or do a modified frog kick, because flutter kicking will tire you out in a short amount of time, compared with other fins. However having said that, I am able to keep pace with other divers who flutter kick exclusively. This is because frog kicking with these fins allows you to glide for a lot longer than with other fins, you get that much thrust out of them. When traveling distances and cruising, Jet Fins are meant to kick and glide. Constantly kicking and pushing water WILL destroy your calf’s and leave you crying in the cramp release position. The correct technique is a must if you want to get the optimum propulsion from these fins.. these fins are NOT for a diver who just want to kick around a reef with little effort or thought to efficient finning and certainly not for someone looking for a solution to cramps. But if you want maximum control, trust and long lasting durability it seems to me these old classics are very hard to beat.
Scuba Tips – Finding Proper Trim
Weighting and Trim
Effortless buoyancy control really comes down to two key factors
1) finding the just-right amount of weight, and
2) finding the best way to wear that ballast on your body and gear to achieve proper trim.
Most of us can understand the importance of the right amount of weight, however if you stop and watch any team divers in action, it’s easy to spot the ones who have yet to realize the importance of proper trim. They’re the divers who muscle through the water in an almost upright position instead gliding along in a smooth horizontal one. They may find themselves constantly fighting to keep from rolling to one side, or to keep their feet from floating toward the surface. Many of these divers may be unaware of their trim problems, either by accepting them as part of diving because they are not aware there can be any differance or because they’ve adopted an inefficient swimming style-learning to lurch back to the center every few kicks, for example-to overcome them.
It often takes new divers about 30 dives or so to get comfortably weighted with the right amount of ballast, but because trim issues are less conspicuous, divers can go for years without realizing them. For the purposes of this review we will focus on trim and assume that you can perform a correct weightng check and already use an optimum amount of weight.
Why Trim Matters
A diver can have perfect weighting and still swim through the water like a large truck. The idea, of course, is to fine-tune your profile so you swim more like a sleek sports car. With traditional BCs and weight belts, however, all of the ballast weight is centered at the diver’s waistline, while most of the buoyant force of the BC bladder is concentrated near the shoulders. As the diver moves into a swimming position, his shoulders are pulled to the surface while his waist is dragged to the bottom, forcing him into an upright profile. This position dramatically increases the diver’s resistance in the water, which increases his workload and air consumption. If the diver is wearing too much weight, this problem is exacerbated on both fronts as the diver adds more air to counter the downward pull of the excessive weight-but even with proper weighting, the problem can be very pronounced due to the physics involved.
In traditional scuba gear your torso basically becomes a lever with a force at each end-buoyancy at the top and weights at the bottom. Levers magnify force, so even a slight imbalance can have a substantial impact. Try this demonstration: lay a two-pound weight on the palm of your hand and hold it at waist level for one minute with your elbow bent 90 degrees. Now extend your arm straight out in front of you and hold it there for another minute. Feel the difference? That’s why proper trim is so important. A pound or two of extra lead in the wrong position can have a dramatic effect on your swimming position.
Here’s how to diagnose your current state of balance and trim. Descend to 15 feet and get neutral. If your weighting is correct, you should be able to hover in the water for one to two minutes with minimal movement. Without changing depth, put your body in a face-down, swimming position with your arms clasped in front of you and your knees bent only very slightly. Using small breaths to avoid rising or falling in the water column any more than necessary, try to hover without moving any part of your body for 30 to 60 seconds. Most divers will find that their body has a tendency to shift or roll during this exercise. Don’t fight it. Let it happen and note exactly what the problem is.
The most typical problem that divers find when completing this test is that their feet have a tendency to move toward the bottom while their upper body moves toward the surface. This means that the center of gravity is too low on the diver’s body and some of the weight needs to be repositioned toward the shoulders. In the event that your feet have a tendency to go toward the surface, you have exactly the opposite problem. You need more weight closer to the lower half of your body. Finally, if your body has a tendency to roll to one side, some weight needs to be redistributed to offset this tendency. Many divers underestimate the impact that a heavy console, a clip-on dive light or some other piece of gear may have on their trim and balance. It may be necessary to shift a pound or two of lead to one side of the body to offset this tendency to roll.
There are a number of ways to move weight around to achieve perfect trim. Many newer BCs have ballast weight pockets located well above the diver’s waist and generally positioned along each side of the tank precisely for better trim control. Ankle weights can be very effective at offsetting positive buoyancy in the legs, or, when placed around the tank valve, to add weight to the upper body. It is also possible to get weights in increments as small as a half-pound, which allows more precise fine-tuning than the typical two- to five-pound block weights. Finally, some weight-integrated BCs are designed so that the ballast weight is higher on the body and more in line with the buoyancy cell. Safety tip: While it’s OK to distribute significant amounts of weight in order to achieve better trim and buoyancy, the majority of your total ballast load still needs to located where it can be ditched quickly and easily in an emergency. Always test your final weighting configuration to be sure you can achieve positive buoyancy and easy surface flotation.
You will need to repeat this test with any equipment changes. For example, your 7mm wetsuit or dry suit will have a distinctively different impact on your buoyancy than your 3mm tropical wetsuit. Likewise, if you use different size tanks, or carry other optional equipment on your gear, your center of gravity may shift. If you are a photographer or videographer, you may also want to conduct this test while holding your camera in position to ensure you will remain stable when shooting.
There are a number of gear modifications that may help you achieve better buoyancy and trim. A backplate and harness BC, for example, will automatically shift three to six pounds of ballast to your torso where it extends along the same line as the buoyancy in your air cell. Whenever possible, you might also consider switching to steel cylinders. These cylinders have different weight and buoyancy characteristics when compared to aluminum tanks, and they are particularly useful for moving your center of gravity higher up on your body and in line with the buoyancy provided by the BC. With both a backplate and negatively buoyant steel cylinders the weight of the objects is moved to the same area of the body as the lift in the air cell, and they are actually attached to the air cell or bladder. This means that the air cell directly impacts the buoyancy of the tank and backplate instead of floating your body, which then must float the weight system typically used in recreational diving.
It may take several attempts to fine-tune your trim, but when you finally achieve this final measure of total buoyancy control, diving will become a new and much more pleasurable experience. Many divers find themselves more attuned to the dive environment and are able to detect small changes in the current, surge and visibility-even the performance of their equipment. But the final, and perhaps the most important, reward is simply longer dives thanks to lower air consumption. For the first time after perfecting their trim, many divers find that air is no longer the limiting factor for their underwater excursions.