[Mal Bridgeman]

For buoyancy - Proper weighting, balanced config, no unnecessary movements, controlled relaxed breathing .... just like everyone else. Fundamentals requirement is within 0.5m of the target depth.

For trim - 30 degrees to the horizontal for a Rec pass and 20 degrees for a Tech pass. Students spend a lot of the course close to a reference point learning to maintain a "geo-stationary" position. Although 20 and 30 sounds a lot, it definitely requires work. During finning it is much easier to get flatter trim but the natural reaction of many divers, when they stop finning, is to drop their knees and adopt a 45degree attitude.

The problem with that is that if a buddy has a problem and you need to swim toward them to help, then your first kick will take you shallower. Your buddy's kick will do the same thing, so at least you meet and can resolve the problem ..... but you now have a buoyancy issue to deal with

The flatter you are, the less the buoyancy change.

Students get videoed to understand how their attitude in the water measures up to their mental image and the instructor will help the student dip forward to get closer to the required trim. Each time progress is reviewed on video. When a student can feel what flat/near flat feels like it's much easier to re-establish. Keeping it when things don;t go so well can take a little longer though.

HTH
Mal

BTW Books, internet and videos don't compare to the real thing though