Tuesday, February 23, 2010

Fin Pivot - Tips and Tricks


Fin Pivot is the first buoyancy skill that a student diver would learn and experience. It builds the solid foundation of scuba diving as every diver would know that buoyancy is the most important skill that a diver need to have to enjoy diving. Thus, divers should not neglect this skill!

This skill will help diver to learn how to control their breath and the amount of air to input into their BCD so as to achieve neutral buoyancy. 

When to use this skill:
- when a diver want to take a photo on a relatively flat surface, fin pivot helps to have a point of support
- when stopping to observe something or waiting at a shallow depth, so as not to be affected by the swells

Some points and preparation

Divers should practice regulator to snorkel exchange at the shallow end - this helps to coordinate the clearing regulator techniques and prevent panic when doing fin pivot.

Patience is key to this skill as buoyancy takes time to work - buoyancy do not work immediately after you inhale or exhale. It takes awhile for your expanded or collapsed lung to work, so be patient!

Divers should not be over-weighted as it would mean that more air / breath is required to achieve neutral buoyancy.

Visualisation [whereby you close your eyes and mentally going through the things / steps that you are suppose to do - as though you are looking through your own eyes and not from a third party perspective] helps tremendously!


Fin Pivot - Power inflator method

Step 1: Deflate BCD fully and lie flat on the ground, facing down. Equalise your ears as this skill should be done at the deep end of the pool. Hold the power inflator mechanism in your hand, with the thumb on the inflate button. 

Step 2: Lock your knees and straighten your body. Hands position in front of you, with the fore arm one on top of the other. (this would help to prevent using of hands to push off) - imagine a genie's hand position when coming out of the lamp.

Step 3: Breath in and out (at least 70% to 80% of your lungs filled - considering a normal breath to be 50%) while lying face down. 

*note: if the diver is correctly weighted, there is no need to inflate the BCD as the inflated lungs would be able help the diver achieve neutral buoyancy
*note: DO NOT hold your breath! breathe in and out SLOWLY!

Step 4: if nothing happens after breathing according to step 3, inflate your BCD slightly by pressing the inflate button once. wait for 5 secs and breath according to step 3.

*note: DO NOT press and hold the inflate button as too much air would inflate your BCD and cause the diver to be over positively buoyant.
*note: If diver ascends to the surface (overly positive), deflate the BCD completely and restart from beginning

Step 5: once neutrally buoyant and knees locked, the diver would pivot at the fin tips. When breathing in, the lung expands, and the diver will ascend slightly. When breathing out, the lung collapse, and the diver will descend slightly.

*note: Diver's body position should be at least 20 to 30 cm above the ground and fin tips should always touch the ground.



Fin Pivot - Oral infation method

Step 1: Deflate BCD fully and lie flat on the ground, facing down. Equalise your ears as this skill should be done at the deep end of the pool. Hold the power inflator mechanism in your hand, with the fingers on the DEFLATE button and your palm covering the hole of the power inflator mechanism.

*note: different models of power inflator mechanism will have different means to cover the hole (or of there is one in the first place)

Step 2: Lock your knees and straighten your body. Hands position in front of you, with the fore arm one on top of the other. (this would help to prevent using of hands to push off) - imagine a genie's hand position when coming out of the lamp.

Step 3: Breath in and out (at least 70% to 80% of your lungs filled - considering a normal breath to be 50%) while lying face down. 

*note: if the diver is correctly weighted, there is no need to inflate the BCD as the inflated lungs would be able help the diver achieve neutral buoyancy
*note: DO NOT hold your breath! breathe in and out SLOWLY!

Step 4: if nothing happens after breathing according to step 3, inflate your BCD slightly by orally inflating the BCD and clear your regulator after putting it back into your mouth but before you take a breath in. wait for 5 secs and breath according to step 3.

*note: DO NOT breathe in too much air into your BCD as you will become overly positive. Give a slight breath and remember to always bubble out when the regulator is not in your mouth.
*note: If diver ascends to the surface (overly positive), deflate the BCD completely and restart from beginning

Step 5: once neutrally buoyant and knees locked, the diver would pivot at the fin tips. When breathing in, the lung expands, and the diver will ascend slightly. When breathing out, the lung collapse, and the diver will descend slightly.

*note: Diver's body position should be at least 20 to 30 cm above the ground and fin tips should always touch the ground.


Below is the video to show you a visual image of the Fin Pivot Skill!




Common Mistakes

1. Over-inflating resulting in positive buoyancy and ascent to surface.

Remedy: DO NOT press the inflate button too long as too much air will be put into your BCD. Also, DO NOT orally inflate too much. patience is the key to this skill as it takes time for buoyancy to happen. Many student divers may be impatient that instead of giving time, they inflate the BCD once more and thus over inflate.

2. Oral inflation - bubbles escape into the water instead of into the BCD.

Remedy: it is either the deflate button is not properly pressed or the diver did not cover the hole of the power inflator mechanism. It is important to practice orally inflating your BCD on land so that you understand what is involved when you are performing the skill underwater.

3. Knees are bent and thus diver is pivot at the knee caps and instead of the fin tips.

Remedy: Lock your knees and stiffen your body! spread your feet slightly wider than your shoulder width so as to achieve more stability when performing the skill.


Remember that buoyancy control is really important for any diver to enjoy their dives and fin pivot is the first thing that divers can learn to practice controlling their buoyancy. It takes a few dives to fully practice and master the buoyancy control. Thus, please do not feel down and give up easily when you find it tough to control your buoyancy. 

Buoyancy is a topic which there are many many points to note and work on. But we shall leave it to next time!


Hope everyone enjoyed the read on fin pivot! =)


Dive Safe,


Lionel






2 comments:

  1. Sorry, but if your feet are dragging on the bottom, your buoyancy IS NOT under control. "Fin pivots" are symptomatic of the fact so many of our dive industry "experts" don't really dive. ('Kinda hare to do when your office is in Fort Collins, Topsham or even Rancho Santa Margarita.)

    The "experts" should all be forced to work on dive boats or at resorts for a year, so that they can see the consequences of their bad advice. Then we'd see just how long the "fin pivot" would last.

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  2. Thank you so much for sharing this post. I am sure it will prove to be beneficial to a number of people.

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