Question on trim...

I'm having a problem with my trim. My lower body wants to sink so I'm in a heads up swimming position. As far as my weighting I have all my weight in my ditchable pockets which is #20 with a 7mm suite. Any suggestions would be helpful.

Brandon

Put your tank higher (put the camband lower on the tank); put some small weights up on the tank valve; or if your BC has trim pockets on the shoulder, move a few pounds of up there.

Blue Space once bubbled...
I'm having a problem with my trim. My lower body wants to sink so I'm in a heads up swimming position. As far as my weighting I have all my weight in my ditchable pockets which is #20 with a 7mm suite. Any suggestions would be helpful.

Brandon

Click to expand...

There is a couple of ways to fix the problem. We do a drill called pivoting around the center of gravity. If you go to www.fifthd.com you can see a video of the skill.

But basically what you are trying to achieve is your center of gravity, which will change as you change you rig. It may be a bit hard to explain via a NG so if I do a poor job call me and I'll see if I can explain it better. 310-550-8004.

The idea is that when you are in the prone [trim] position your head should be slightly up, your belly button area should be the lowest point and your legs will be in a 90 degree angle.. However, depending on your configuration, if you keep the legs in a 90 degree angle it's likely that you may be to "top" heavy [ as in your northern part of your body. If you extend your legs about 15 degrees you can extend the area that you are trying to balance. Generally speaking when you are having problems in terms of head up, it's likely you'll want to tuck your legs as close to the bottom of your tanks as possible. By shortening that center of gravity, you'll achieve a more head down position..

Hope that helps, but check out the video and if you are still having problems call me..

Later

I can't seem to find the video of that drill, I found allot of others but not that specific one.

Blue Space once bubbled...
I can't seem to find the video of that drill, I found allot of others but not that specific one.

Click to expand...

The file must be corrupted, it was on there a couple fo days ago.. I'll send Andrew an e-mail and see what is going on..

Absent the video for a moment, think of laying flat on a bed, with head slightly up. The drill is then to bring your legs as far as you can as if you were going to hit the bottom of the tank.. That will generally pivot your head down.. If you were to extend the legs about 15 or 20 degrees that would tend to pick your head up.. So somewhere between the legs in a full 90 degree angle and an extended 75 or 70 degree angle is your center of gravity.. It's like riding a bike, you play around with this drill until you find a center of gravity [ CG] that works for you..

But if as you suggest that your head is titling up then you'll need to suck your legs in closer to the 90 degree position and that should help your trim..

Let me know how it works out..

Later

Getting some of your weight up higher can help. A back plate/chanel weight, a couple small hard weights threaded onto the cam bands or whatever it takes. As MHK said body position effects trim alo but it's like a dog chasing his tail. In my experience you can't get the right body position unless you're close to being balanced and you don't know if your balance is on the money until you get the right body position.

A wet suit makes it worse because even if your good at the surface as you decend the suit looses buoyancy. Then you add air to the bc and bingo...the bc want to lift your upper boddy while the weights on the hips want to sink your feet.

Are you saying you can't achieve perfect trim with a wet suit because thats all I'll be diving in for now.

Blue Space once bubbled...
Are you saying you can't achieve perfect trim with a wet suit because thats all I'll be diving in for now.

Click to expand...

Not at all.. What I'm saying is that your Center of Gravity [ CG] will change depending on whether you are diving, for example, a single AL 80 in a 3mil wetsuit -v- a double set of 104's in a drysuit..

Part of why I'm trying to discuss the skill is because ad hoc ideas like using weights on the tank is using gear to solve a skill problem. Accordingly, if you learn how to adjust, and learn the skill you'll have trim no matter what tank(s) you dive, no matter what westuit or drysuit you dive..

Once you understand the interplay between balance, trim and buoyancy, and how to adjust them, the rest of diving is easy.. The fundamental platform must get squared away and learned first, and then from there you can make any adjustment to balance yourself, trim yourself and adjust your buoyancy..

Later

Na, the wet suit just makes it a bit more of a trick. In other words, trim can be adjusted to be perfect at depth, but it will vary somewhat at your safety stop when your BC is empty.

For the warm water weenies it is easy because the wetsuits are thin (or nothing).

My advice: don't run out and buy a drysuit unless you are cold.

By the way, I dive wet and use ordinary weights on the top tank strap on a Transpac II. Works like a charm. Your exact solution will depend on the BC you are using.

I have no way of knowing if the 20# of weight you use is optimal, but always try for less weight. My test is neutral bouyancy with no air in the BC on a safety stop at just below 10 feet with 500 to 800 psi left in the tank.

Blue Space once bubbled...
Are you saying you can't achieve perfect trim with a wet suit because thats all I'll be diving in for now.

Click to expand...

No I'm not saying that you can't but it's a little more work especially with a heavy suit. The suit effects buoyancy just like your weights and your bc. Since the buoyancy of the suit changes with depth and you compensate with the bc there is a shift in your center. Also remember that the buoyancy of the tank changes during the dive. I find a single Al tank and a heavy wet suit to be about the hardest to tune. I only dive this way when teaching OW classes (shallow) in the heat of the summer.