Trim? Let's discuss how to manage trim

[HowardE]

WARNING: This line of questioning often leads people to purchase BP/Ws. . .

Not to start a bp vs jacket battle, but I recently switched to bp from jacket. I have noticed no difference in my trim from one to the other. I have about 220 dives in a jacket, and about 20 in a BP/W... I chose a BP/W so I don't have to carry as much weight when I dive in my DS in the winter. In the summer, I only carry 2 lbs. in my wetsuit, so that I'm about -1 in the water, so I can lay in the sand and capture images of jawfish and blennies and such.

 

[loosebits]

What do you refer to drifting as? Swimming or just being neutral??

Don't understand the question. My point is though that when you are doing stuff (swimming, whaling your hands around, whatever), you are constantly making corrections to your trim and you can't really tell if you are actually trimmed out or not.

Btw, switching from jacket to a bp/w should have a drastic impact on your trim (not necessarily good but drastic, especially if its a SS plate). If you didn't notice a change, that's because you've always subconsciencely used your fins to adjust your trim (as suggested by your first post). Try holding still and see where you end up.

 

[xiSkiGuy]

Another point to remember is that some tanks will change your trim depending on how full or empty they are. For example, I'm properly trimmed out with full Aluminium 80 doubles, a steel backplate, and 4lbs on my weight belt. Take the same setup, but have only 500psi in my doubles, and I'll be head heavy.

 

[loosebits]

I'd write something, but Joe's already done it better than I can here.

Hey look, a lever. Great minds...

 

[loosebits]

Another point to remember is that some tanks will change your trim depending on how full or empty they are. For example, I'm properly trimmed out with full Aluminium 80 doubles, a steel backplate, and 4lbs on my weight belt. Take the same setup, but have only 500psi in my doubles, and I'll be head heavy.

Don't you mean foot heavy? I assume you wear your tanks on your back

 

[HowardE]

Don't understand the question. My point is though that when you are doing stuff (swimming, whaling your hands around, whatever), you are constantly making corrections to your trim and you can't really tell if you are actually trimmed out or not.

I guess - what I mean is... When you're doing a drift dive, and just going with the current... is that "swimming" in your example, or "being neutral" just hanging out?

Personally, like I said, it's mostly a matter of mind control.

There are those of course, who think that education is the only answer to everything, so a course in how to maintain trim could be for you (to the O.P.) ... or you can just dive a lot and learn on your own... it will come.

 

[wreckchick]

What I've noticed is that there is a lot I can do to manage my trim that has nothing to do with gear. Once I've got my gear mostly right, the rest I do with my leg position, arm position and head position. I can take my normal good trim and mess it up pretty well by extending or contracting arms and legs or letting my knees drop or looking behind me through my legs. The flip side is I can take sub-optimal configurations and "fix" my trim using the same methods. Body position is 75% IMNSHO.

Rachel

 

[xiSkiGuy]

Not to start a bp vs jacket battle, but I recently switched to bp from jacket. I have noticed no difference in my trim from one to the other.

I didn't mean to imply that you cannot have proper trim in a jacket style BC. However, in my experience the most common trim issues divers have are "feet heavy" issues. Often a backplate moves weight to a beneficial location for those divers. The same can be accomplished by putting weight in the trim pockets of a BC or using a weight pouch on tank cam bands.

 

[xiSkiGuy]

What I've noticed is that there is a lot I can do to manage my trim that has nothing to do with gear. Once I've got my gear mostly right, the rest I do with my leg position, arm position and head position. I can take my normal good trim and mess it up pretty well by extending or contracting arms and legs or letting my knees drop or looking behind me through my legs. The flip side is I can take sub-optimal configurations and "fix" my trim using the same methods. Body position is 75% IMNSHO.

Rachel

I agree that proper body position is important and that body position and fining can cover for suboptimal setups. I think it is best for the person just beginning to examine trim to look at getting their gear balanced like loosebits described and then explore how bending your knees, where you hold your arms, or then extent to which you arch your back changes things.

 

[wreckchick]

I don't disagree at all but what I find is that people will find the sweet spot then lose it due to body positioning instead of thinking holistically about the process of achieving good trim. IME it's best to set a configuration and work with it over several dives before makes changes. It gives the diver a chance to work on body position and see what he/she is compensating for to improve trim, then do gear tweaking, dive more, rinse, repeat.

R