Trim issue

[AggieDiver11]

Howdy guys,

I've been having a slight trim issue I can't seem to get nailed out. My feet tend to drop after a few moments when still in a horizontal position. It's infrequent, and isn't a problem when I move, even slightly. Could positioning of the tank on my wing affect this at all?

Buoyancy isn't an issue at all, I can place myself and change depth with ease using my lungs, but once my feel drop when i'm motionless, it makes everything else wonky.

Any suggestions are welcome!

 

[bs63366]

Your tank position will definitely affect your trim but that seems odd to be your tank if its infrequent. you might try to place your tank a little higher if it happens at the beginning of the dive or a little lower if its at the end of the dive, assuming you are diving AL80's. You might try to put a small amount of weight in a weight pocket on your top tank band, I would start with one pound if you choose to do this. One last thing that I can think of right now could be your fins might be negatively balanced and weighing your feet down a small amount. Just a few thoughts...

 

[Bubbletrubble]

I'm going to assume that you are properly weighted...
It sounds to me like you just need to optimize your weight distribution to promote static horizontal trim. You'll need to shift weight towards your head in small increments until you find a configuration that works for you. Shifting your weight around affects the location of your center of gravity. It's very much a trial and error process.

There are many ways to shift your weight around. One method is changing the positioning of your tank. If you move the tank up relative to the BCD, you should be shifting your center of gravity higher. It's worth a shot, but understand that there are limits to how high the tank can be shifted up. Let comfort be your guide.
bs63366 mentioned tank camband weight pockets and different fins. Those are certainly legitimate options. Some BCDs have built-in trim weight pockets positioned at the level of one's shoulder blades. If you've got 'em, use 'em.

This issue of how to achieve horizontal trim is one that pops up frequently here on ScubaBoard. One of the SB members who is also an instructor (ae3753) has put together a couple of excellent essays on the subject:

• Horizontal Trim 101 - Uses
• Horizontal Trim 101 - Levers

As you gain experience, you'll realize that body positioning can compensate for a surprising amount of suboptimal weight distribution. This can consist of bending your knees, controlling hip angle, and placing your arms out in front of you. Obviously, you don't want to be contorting your body so much that it's uncomfortable, though.

Hope this helps...

 

[AggieDiver11]

I'll test out the small amount of weight on the top camband tonight while i'm waiting for the OW class I DMC for to come out and get in the pool.

Propelling myself around, buoyancy and trim aren't issues, which leads me to think, as was suggested, that maybe it's the negativity of the fins (OMS Slipstreams, however I wear 5mm booties), or the tank is just slightly off enough to where it shifts my center of gravity back.

Just for clarification, I wear a SS BP with an Oxycheq 30# Mach V Wing. I'll try out the suggestions tonight and see if they help, thanks for the input! It's close, but the perfectionist in me wants it to be flawless and effortless.

 

[wve]

... but the perfectionist in me wants it to be flawless and effortless.

Sounds like a Aggie

 

[Bubbletrubble]

Hmmm. I thought that OMS Slipstreams were just about neutrally buoyant. With 5mm booties, I'd think that your feet + fins shouldn't be "too heavy" in the water (promoting head-up/feet-down trim).

With a BP/W rig, I've found that the XS Scuba weight pockets work great on the tank cambands. This is only helpful, however, if you have some weight that can be shifted there. If you are diving in fresh water with little or no exposure protection (warm pool?), you might not have much shiftable ballast. This could mean that sliding the tank up a little might be your best option.
FYI, shifting weight to camband weight pockets makes that weight non-ditchable.

You mentioned that you are using a SS BP, but you didn't specify how thick your exposure protection is and what kind of tank you use.
How much lead are you carrying in that single-tank configuration?

 

[Hatul]

You can also see if the wing can be moved down on the plate?

 

[DevonDiver]

Using weight pockets on your upper cam band is a good fix. Just make sure that you can afford to have extra non-ditchable weight within your 'balanced rig'.

Got any photos of yourself in the water? How you hold your legs can have an impact on your overall trim. So can your head position, and ability to arch your spine to bring your shoulders, hips and knees level.

 

[lionfish-eater]

Try a pair of force fins. They are lightweight and have enough power for most conditions. I have the basic ones but plan to upgrade to the longer ones.

 

[AggieDiver11]

I think I may have figured it out. In the pool, I normally wear a 2-3mm shorty, which allows me to wear no ditchable weight in the pool. The tanks are standard AL80s. I dropped my wing about an inch or so after noticing it tended to lift the upper section of my body when air was added. Dropping the wing allowed me to raise the tank a little bit, which seemed to make the difference.

On a random note, I also had the opportunity to try a set of steel doubles recently, and found trimming out in the doubles was easier than the singles. Definitely caught me off guard to say the least.

Thanks everyone for the help!