Weighting for horizontal trim

[Slmason.72]

I Dive and love my aqualung dimension i3, but am having a hell of a time finding neutral horizontal trim. With a 3 mil wetsuit, 3 mil vest and hood and 3 mil shorts, I use 8 lbs in fresh water, 4-6 in salt with a shorty... I keep all of this weight in the trim pockets, have the tank shoved up so far I cant get my head all the way back and still can't keep from going feet down when neutral... Mind you, I have no trouble maintaining neutral, even at the end of the dive, but I'd like to get my trim set horizontally. I have about 30 dives under my belt and have even done a PPb course hoping to fix this... The instructor ended up just shaking his head. I do have a very low body fat percentage and am somewhat muscular. I sink like a stone and cannot float (think swimming not diving) at all in fresh water without very actively paddling or kicking. I can snorkel in salt water without a flotation device, but only horizontally... If I go vertical, I have to kick to stay up...

I have heard of something called a trim leveler but the website is dead... Is there a way to move the weight further up my back? While typing this, I just had an idea... Since I have the tank shoved so far up, I might have room for another tank band near the shoulder of the tank, I could strap a couple of small weight pockets up there and try to get my cent of gravity to shift even more... I'd really like to get my tank back down a few inches as I'm not fond of the dimple starting to develop in my skull, yet am not willing to give up and hang vertical all of the time.

Any thoughts or suggestions? Anyone else have this problem?

 

[JamesK]

Are you bending your knees at all? are you putting your arms out in front of you holding your hands? I am asking because you can use your limbs to move your center of gravity. by bending your knees at a 90* angle and placing your hands forward of you, you move that center of gravity. if you are not doing this, and need a pic to see it better, let me know.

 

[Slmason.72]

I am bending my knees, even my hips to keep my but tucked tight against the tank, sometimes to the point my back hurts. when stationary and trying to hover, I put my arms out in a typical skydiver pose.

Once I have given up trim drills, I go with the flow and just have a fun dive... I can stay horizontal when finning and usually have my arms tucked up underneath me.

Just ordered an Intova video cam... Sounds like I have already found a good use for it... I'lltry to get some video in the coming weeks.

 

[TSandM]

The basis for horizontal trim is body posture, as James mentions above. Arms out in front of you, head up, body flat from the shoulders to the knees, and knees bent to the degree required by your balance. If you are dropping your knees (flexing at the hip joint) you will tend to rotate feet-down -- the same thing will happen if you try to rear up to push your head back.

The key to figuring out static weighting is to achieve a stable platform, even if it requires some kicking to get there, and then, once your buddy confirms you are correct, STOP MOVING, while holding the posture. If you rotate feet-down at that point, you know you have too much weight below your center of gravity. Options to fix that are to move to a positive fin, use a thicker wetsuit bootie, put more neoprene on your legs, move your tank or trim weights up, or use a dry suit.

It is EXTREMELY unusual for someone to be unable to balance a single tank rig. As James said, if you can get photos or video of you, it would help us diagnose the problem.

 

[KevinG58]

I have used that BC and it was not well-fitted and I had "heavy feet", and guess what would happen if inverted to take a picture in some crevice? Head heavy!

Until I rigged a crotch strap and stopped it sliding up my body. (Not knocking the I3 almost any BC is not going to work properly when poorly fitted.) It was then a very different rig and easy to trim, great until I saved up and bought my BP/W.

Edited for clairity

 

[g1138]

On the topic of body posture, use your abdominal muscles.
- Stretch out your back as if you're tip toeing
- arch the upper back
- plank your stomach
- clench your butt
- bend your legs at the knee
- thighs shouldn't be bending below your stomach, they should be inline with it
- bottoms of your feet go parallel with your intended trim horizon

Tank should be no higher than the base of your head; you can rest your head on the first stage if needed. Shift your weight around if you need to but body position is really 80 percent of the problem if you're properly weighted.

 

[eelnoraa]

Very good advices above, you should do all of that, have a friend video you if possible to see if what you are doing is really what you think you are doing. Not mean to offend you in anyway. Same thing happened me: I though my knees were bended 90 degree, but they were not even close due to thick exposure suit I was wearing.

So once you know your prosture is correct, if you are still leg heavy, you just have to find a way to move weight up your body.

 

[RJP]

I agree to a certain extent with the "body posture" people above, but will add that it shouldn't be - and it isn't - as much work as they might be making it sound.

It's not like a golf swing - chin down, left arm straight, back at 45deg, right shoulder dropped, left hand over right, toes even, wrists relaxed, knees bent, weight on left foot, chin up, straighten those knees, no, no, weight on RIGHT foot, bend that left arm, you're dropping your right shoulder TOO much, shift your weight a little more, chin down...

Sounds like you've got a lot of neoprene on your upper body and not a lot of weight. Your BCD is also fairly buoyant. If you hadn't already bought the BCD I'd say "get a BP and wing rig" which would remove some of the inherent buoyancy, but I'm assuming that's not an option.

Perhaps try an ankle weight on the tank valve to shift more of your weight towards your head... along with some of the body posture advice already given. With this you might also be able to shift the tank down a bit as well.R

Ray

 

[TotDoc]

With a 3 mil wetsuit, 3 mil vest and hood and 3 mil shorts, I use 8 lbs in fresh water, 4-6 in salt with a shorty

Maybe I am reading this wrong, but are you wearing multiple layers under a shorty, but no full wetsuit? If you have all that buoyancy up top, but nothing down low, that may be a big part of your problem! Like you, I sink like a stone when swimming - specifically, my legs go down, and the rest of me follows. If you try wearing a full suit, the neoprene over your legs will balance you out and help you keep your legs up. When I was diving an i3, I had no problems maintaining horizontal trim in a full suit, but I could never quite get it to work in a shorty.

 

[Slmason.72]

I'm wearing a full 3 mil suit with a 3 mil hooded vest and 3 mil shorts underneath.

Thanks for the advice. I'm hoping to get wet this weekend and put some of it to good use.