Good Trim and the Fin Pivot?

[Snowbear]

... I,ve never seen that level of skill among recreational divers.
...
Tell me when and where. I'm hurting for money right now but I will immediatle start planning for a trip where I can see 75% of the divers in the water trimmed well (in a typical recreational environment anyway especially where they need much of a wet suit)

Recreational charter, Puget Sound, 16 divers, 2 dives, most in dry suits, a couple wetties, serious fun was had by all

 

[Rick Inman]

Recreational charter, Puget Sound, 16 divers, 2 dives, most in dry suits, a couple wetties, serious fun was had by all

Yeah. I've seen several groups of divers with good trim in the sound. And, BTW, to those diving with me at Cove2 when we were all hovering around that stumpy squid and my fins touched the bottom and I silted it up, ruining it for all, I was just demonstrating my fin pivot.
Really...

 

[d33ps1x]

Yeah. I've seen several groups of divers with good trim in the sound. And, BTW, to those diving with me at Cove2 when we were all hovering around that stumpy squid and my fins touched the bottom and I silted it up, ruining it for all, I was just demonstrating my fin pivot.
Really...

One small step for man...

 

[Snowbear]

One small step for man...

...One giant leap for squidkind?

 

[MikeFerrara]

Mike, I agree with you that good trim comes when your center if gravity and your center of beuyency are very close. Now lets assume you have all the conditions necessary to be perfectly horizontal and your trim is tweeked. I will go as far as saying that your center of gravity and your center of bueyency are exactly the same.

NOW add bueyency to one end and not the other by doing something as crazy as putting air in your BC (last I checked that was on the upper part of one's body) or putting more air in your lungs. Without doing anything but hanging out superman style (horizontal) you WILL shift your center of bueyency and as such you will not be able to maintain a horizontal attitude without action.

I say this because physically that is what has to happen. Now you can employ techniques that will shift the center of bueyency back so that it stays roughly consistant but then you are contorting yourself and going out of horizontal (yes arching your back will have this effect but then you are not jsut going up horizontal with no intervention are you?)

I guess my simple mind looks at pjysics in simple terms of fources acting on an object. That said, I am probably Doing It Wrong (DIW).

Pete :rasta:

BUT that all said Mike, I would love to dive with you and check it out some time. If you are ever in New England look me up

We've been through this before. The points you make are not mechanically wrong. None the less we can ascend and descend without foreward motion and do it horizontally. Certainly there are shifts during the dive. Tanks become lighter ect.

Go watch the 5th D videos to see how it works in practice.

 

[perpet1]

Perpet,

I know you believe what you say is true, but I can attest that you are just plain wrong in your beliefs here.

When one is trimmed and weighted properly, the center of gravity is approximately the center of the chest. By inflating your lungs, you DO NOT change the CG and therefore your trim does not change. You can EASILY (when practiced) change your position in the water column-straight up and down- by just using your lungs. Actually, it becomes so easy that you don't really even think about it. And you NEVER go head up or feet up unless you wish to.

You maybe cannot do this, and obviously you have never seen anyone do it, but those with the proper technique use it all the time.

One place that it is taught is the DIR Fundamentals class. It's one of the basic requirements of that class. Solid trim, and solid bouyancy control. Of course there are others that dive this way also.

Find some of the DIR divers in your area, and ask them to go for a dive. Then report back to us what you see.

I assure you I am not wrong although with my extremly limited experience and brain power it may seem that way or it just may be my improper dive technique.

Now you yourself state that this is a skill that takes practice. The practice you speak so hightly of, is it limited to finding that perfect trim or are there techniques you must use? This is because it does not just happen once you have properly adjusted your trim. This is a skill that requires overt action on the part of the diver. I stated that yes, if you employ the proper technique then you can overcome the shift in your CB but with no action what you are saying is impossible.

But you are right I have not been graced by the almighty DIR. It is obvious that I must be Doing It Wrong.

 

[perpet1]

...would they agree to the dive though.

I know I started this but a DIR bash is not waht I had hoped this would turn into.

 

[Don Burke]

Hi,
I'm brand new to diving and trying to get my "trim" under control. I'm about to testdrive my new BP/Wings with tank weights. It occurred to me that the fin pivot drill just confirms that you're not weighted properly. You inhale, and your upper body (only) rises, exhale and you sink. Does this make sense? I've read that if you have proper trim/weighting, your body should be horizontal in the water. Any insight? Thanks.

It's an exercise to demonstrate a few things. If you're wearing negative fins, you can move your CG a bit by bending your knees, so yes, a fin pivot can be executed with proper trim.

Beyond demonstrating how the lungs affect displacement and that proper buoyancy control means you go up and down as you breathe, I don't see much point in it. I certainly don't think it is something that new divers need to repeat once the point has been made.

 

[MikeFerrara]

Perpet1,

Go watch the video hen come back and comment.

 

[chrpai]

I know I started this but a DIR bash is not waht I had hoped this would turn into.

Don't worry about it perpet, all Detroit Diver knows how to do is insult posters and then try to sell the poster one of his classes. It's all part of the "create a need" aspect of GUE marketing.