Fixing diver trim and weight placement

[inquis]

I totally get that but if I go horizontal and motionless and my head rises you say "shift weight toward the end that rises" so I should move weight toward my head. Really!?

Yes, raise some weight in that particular case. The fact your head rises when horizontal indicates you're head-light / foot-heavy.

I suspect your "Really!?" comment is sarcasm. (My apologies if I've misread.) What you're assuming/described is the intuitive situation, and the obvious solution is the correct one. OTOH, the OP described the opposite scenario, and the obvious path of "stable with feet low = raise weight" would be exactly backwards. The horizontal test conveniently resolves that ambiguity.

 

[crofrog]

The horizontal test conveniently resolves that ambiguity.

It's funny how even this is controversial...

 

[inquis]

It's funny how even this is controversial...

One of the funniest things I've ever seen was a buddy in doubles going on about strapping weights to the tank valve or wearing a freediver neck weight to correct his seahorse trim. He finally let me hold him gently in my outstretched arms and orient him horizontal while he was neutrally buoyant. When I dropped my hands, he was like a bucking bronco -- absolutely galloping around in a circle, kicking for all he was worth and flapping his arms to avoid going ass over tea kettle. Sometimes awesome pictures are just not enough to explain physics.

 

[JoeTPhilly]

These two videos from a GUE instructor may be of interest: