1. Sports

Trim Weights and Scuba Diving

By

Trim Weights and Scuba Diving Image copyright istockphoto.com, Jman78
My female open water student had a problem: she was well-endowed. During my open water courses, I teach divers about proper trim (or swimming position). Try as she might, my student could not maintain a horizontal position in the water. Her chest kept floating up, forcing her vertical. I could see that she was becoming frustrated, so I let her in on a little secret - boobs float. With proper technique, most divers can achieve correct horizontal trim in the water. However in her (rather extreme) case the regular solutions such as arching the back or bringing the feet up did not solve the problem. I finally fixed her trim using trim weights, a trick many divers are unaware of. Trim weights can make a huge difference in maintaining a flat position underwater.
Trim weights are weights that are placed in positions other than a diver's weight belt or integrated waist weight pockets. Many modern buoyancy compensators (BCDs) are designed with trim weight pockets on the shoulders or upper back. Divers can also place trim weights on the tank, by sliding them onto the BCD tank band or a separate tank band high on the tank. Trim weights should be lightweight - one or two pounds will usually do the trick. As trim weights can not be removed in an emergency, it is important that the majority of a diver's weight is still worn on a ditchable weight belt or in removable weight pockets integrated into the BCD. By removing the weight belt or integrated pockets containing most of the weight, a diver can still establish positive buoyancy on the surface in an emergency
In my diver's case, I attached two one-pound weights to clips using zip ties, and clipped them to the chest d-rings on her BCD. The effect was immediate. My diver was smiling so much once she finally achieved proper trim that she nearly lost her regulator. She still had to keep her feet up and arch her back to stay in position, but with just a little added weight to her upper body, these techniques finally worked! An elated diver and one very happy instructor surfaced from the dive forty minutes later.
More tips for easier diving:

• How Does Proper Trim Make Diving Easier?
• Follow Your Head: A Tip for Easier Buoyancy Control
Make Descents Easier and More Enjoyable

Creating trim weights using clips and zip ties is a temporary solution. It worked well to try out the rough positioning of the weights and check to see if they improve the diver's trim. However, once he determines the trim weight position that works well for him, a diver would do well to invest in a BCD designed with trim weight pockets in the appropriate position.

There are several concerns associated with using clip weights regularly. Clip weights and other gear that dangles below the diver's horizontal body line may accidentally bang into coral or otherwise damage the underwater environment. Clip weights are also very easy to lose. After many uses, plastic cable ties commonly used to attach weights to clips may fatigue, and the weights may fall off of the clips during a dive. Not only is it frustrating to lose a weight mid-dive, leaving lead laying around the ocean's bottom is not great for the environment. A diver may also become positively buoyant upon losing a weight, and may be unable to stay at the desired depth.

Before resorting to trim weights, divers can try getting into proper horizontal trim using a variety of techniques: adjusting the height of their feet, bending their knees, looking down, extending their arms in front to change their center of gravity, and arching their backs. However, divers have different body compositions, and if you have a buoyant chest or very negatively buoyant feet and legs, sometimes these techniques simply don't work. Trim weights may be the answer.
  1. About.com
  2. Sports
  3. Scuba Diving
  4. Basics
  5. Learn to Dive
  6. Trim Weights Can Improve a Diver's Swimming Position

©2014 About.com. All rights reserved.