Trim, Buoyancy and Arm Position

[jar546]

I have noticed 4 basic positions of divers in the water:

1) The skydiver with arms held out in front with excellent buoyancy control
2) Arms behind the back with excellent buoyancy control
3) Arms crossed and held against the chest or stomach with excellent buoyancy control
4) The flailer with arms everywhere and little to no buoyancy control

Which one are you and can you add any other positions?

 

[Blackwood]

I generally dive with my arms out (I guess position 1). Not sure why you think arm position relates to buoyancy control...

 

[jar546]

I generally dive with my arms out (I guess position 1). Not sure why you think arm position relates to buoyancy control...

I understand your comment. Should have left the word buoyancy out of there. Buoyancy plays a part in trim but trim does not play a part in buoyancy that I am aware of.

 

[kanonfodr]

Deep-Sea Sherpa Horizontal Trim 101 – Levers

Hand position can be anywhere (including behind your head) and horizontal trim can be maintained as your arms have only a small effect on trim, with the bigger levers being your head, legs, and posture in general (stretched out, not necessarily bending across your lower back). The key thing to remember is that your hands are your tools: they're shining a light or working with a line or signalling to your buddy so there is no set "right" position for them to be in.

Lots of wetsuit divers fold their arms across their chest, whereas drysuit divers tend to have their arms out in front of them to help balance the tendency for a drysuit to have floaty feet. Brand new recreational divers may not have a clue that their hands AREN'T supposed to flail around, technical divers tend to wear their gauges on their wrists so they want their information in front of them (think: dashboard). If an individual is handling a camera then their hands are manipulating that.

For myself, I tend to have my arms out in front of me where I can see my gauges, point my light at an interesting critter, and then get some good video of him. But for the longest time I just folded my arms across my chest so they wouldn't be flailing, but I could still read my gauges just by ducking my head real quick.

Oh ya, and you forgot one more that I can think of: the diver who doesn't use their hands much but still has poor bouyancy and trim. I was that guy for a while.

Peace,
Greg

 

[synctek]

If I'm diving warm water w/ shorts and a rash guard, I usually tuck my thumbs in my cumber bun and just chill. If I have to wear that #$%^& 7mm wetsuit, I usually clasp my fingers and rest them under my chin or near it.

I just bought a Hollis HD100 back inflate and tested it this weekend!! - coming from renting and wearing jacket-style for a while, back inflate is nice and way more streamline than a jacket. That said, I tried both methods to see which felt most confortable......putting my hands out front with the wetsuit on still seems to be the best way to go.

 

[kanonfodr]

I understand your comment. Should have left the word buoyancy out of there. Buoyancy plays a part in trim but trim does not play a part in buoyancy that I am aware of.

Actually, horizontal trim does play a part in bouyancy because if you present a larger surface to the vertical water collumn you won't be as prone to "Bungee Diver" yourself up and down with breathing, since that extra resistance is limiting the speed at which you move up and down.

Deep-Sea Sherpa Scuba 101 – Ascents and Descents

Peace,
Greg

 

[boulderjohn]

I generally dive with my arms out (I guess position 1). Not sure why you think arm position relates to buoyancy control...

I understand your comment. Should have left the word buoyancy out of there. Buoyancy plays a part in trim but trim does not play a part in buoyancy that I am aware of.

In a way I think it does play a part, Marc.

When divers are working on technical diving skills, one of the things they learn is to hover motionless in horizontal trim. That requires excellent trim and excellent buoyancy control. One of the factors in trim is the distance of weight from the center of gravity. Divers learn to bend their knees to shorten the length of their legs and bring the weight of their fins closer to the center of gravity, and they learn to extend their arms to extend the distance in that direction. This allows them to hold a position in good trim.

When moving, though, this is less important, because the kicking action helps maintain the trim. In that case, the extended arms are less important, and they can be pulled in to lessen drag.

EDIT: I forgot to mention that technical divers are usually holding a light in the hand, which requires an extended arm.

For most recreational divers, the key is to avoid using hands and arms at all, and so bringing them in to the body and holding on to something prevents them from using the hands and it helps reduce drag. Folding the arms is common. So is clasping the hands in a prayer position. Some people will hold on to their BCD straps. Some people do all of the above, depending upon how they feel at a particular moment.

 

[DevonDiver]

I like my hands out in front. When I've been diving a lot (4-5x a day, weeks on end), my back can ache...so I like to 'stretch out'.

Often, when teaching, I hold my hands behind my back, below my tank. Students tends to replicate this...and it quickly gets them out of the instinct to scull with their hands.

 

[Saudi-Diver]

If I am in a Dry suit I dive with my hands folded across my upper chest my buddy calls it the "heart attack position" so when I roll away from my auto dump its effectively at the highest point on my body. When diving dry I tend to dive in the "at ease" position with my arms behind my back. Only exception to this is night diving.

 

[Garrobo]

I usually fin about with my hands holding the bottom of my tank.