What is "horizontal trim"?

[NJMike]

In many other threads people have referred to "horizontal trim", holding 'it', maintaining it, adjusting it, etc.

In a thread I was just reading about ascending on a line, some experienced divers were giving advice to a newbie who had a bad experience ascending on his first ocean dive.

Several people made references to horizontal trim...to ascend maintaining horizontal trim, etc.

I am a newbie also and had come to define 'horizontal' as meaning 'prone'. So were they suggesting that a technique would be to ascend in a prone position? Or does 'horizontal trim' mean something else?

 

[Dave in PA]

Without seeing the references that you refer to, I would say, Yes, Horizontal Trim means prone. Baically, your entire body is at the same depth.

 

[spectrum]

You are correct.

A horizontal ascent presents your full body profile as resistance to slow your ascent. A disadvantage is that it provides less visibilty to what's happening above so it's sometimes wise to go vertical near the top IMO.

On the way down being horizontal is my preference right from the top. My body profile slows the fall and I can see where I'm going to allow for a nice stop without touching the bottom.

While swiming it means you are punching a smaller hole through the water and using less energy. Also by being prone you are not creating "lift" by moving a hozontal body through the water. This means you are mor elikely going to hold horizontal when you halt.

It 's usually a combination of ideal weight placement, technique and a state of mind.

Pete

 

[Kim]

I'd like to believe that my position in the water is horizontal in my avatar.....
(well....nearly! I was looking at the guy with the camera! )

 

[BabyDuck]

kim, go back to the original pic & do a little creative cropping...

mike, it's what they said & you guessed - being 'flat' compared to the top of the water & bottom of the ocean or lake or quarry or whatever.

 

[miketsp]

Yes, they mean prone.
There are arguments for and against this.
For example: Some like to do it because it looks "cool".
Others because your whole body will be off-gassing at the same rate.

Personally while I might start an ascent horizontal I always change to vertical on the grounds of safety as I like to know what I'm rising into. This really depends on the vis. If it's good then you can go up horizontally and have a good idea what is around you.
OTOH in poor vis, in a horizontal position with a thick wet suit I have some difficulty turning my head to look behind and above me whereas in a vertical position I can do a 360 degree (or to be more precise 4*pi steradians ) scan with flick of a fin.

 

[NJMike]

Very good. Thanks to all.

 

[Kim]

kim, go back to the original pic & do a little creative cropping...

Oh c'mon...it's not THAT bad.....

I agree with Mike though about ascents. It's good to know what's above you and that's easier to see from a vertical position. I heard a story from my instructor about someone who ascended into a Portugese Man 'O War....not nice. I'll hold safety stops horizontal but if I'm moving up I'll switch.

Of course some people just lay on their back for ascents.....no problems with upward view then!

 

[PerroneFord]

Of course some people just lay on their back for ascents.....no problems with upward view then!

Exactly. Though it does present some issues if you are diving in a team and others aren't doing it also. I don't know how well a gas-share on ascent would work that way.

 

[Fastmarc]

Is it possible for some people to just have difficulty staying horizontal when at rest because of their phisical make up?
I am one of those people that if I try to float in a pool, my feet sink very easily. Even though I have made it a lot better by shifting some weight around, my feet still sink when at rest. I have no problem staying horizontal while swimming or desending (which is also my preference).
Maybe more buoyant boots?