All our diving gear makes us positively buoyant (float). Even dive tanks act like a buoy when the air inside the tank is reduced. Neoprene is foamed and naturally try to make us positively buoyant. If you think that our exposure dive gear like wet suit, gloves and dive boots are made of neoprene.
We, as scuba divers want to stay underwater, but the equipment we use don’t let us to do it. In fact, some experienced divers can become negatively buoyant (sink) when steel tank and shorty as a dive suit used. But it is still requires effort to stay underwater. Beyond this, we cannot always wear a shorty, right?
Need for an underwater weight becomes a need at this point. Scuba divers generally use weights made of lead.
How much weight a diver needs depend on:
- diver’s weight
- material of scuba tank used (steel is heavier than aluminum)
- type of dive suit worn (a shorty will make you less positively buoyant (float) than a full wet suit)
- extra exposure gear worn (like hoods and rash guards that will create an extra positive buoyancy to the diver)
Types of Underwater Weight Systems
There are 2 main types of underwater weight systems. Each of them can be used by every diver. What is important is the comfort of the diver when choosing an underwater weight system.
You can ask your instructor about which system to use and ask for his/her opinion first. This will dive you an idea about the weight system you should use. But then try different systems and find the one that makes you feel comfortable.
There are 3 sub categories of weight belt.
The most common type of underwater weight system is the weight belt in recreational diving. A belt usually made of nylon webbing and a quick release buckle (made of chrome or plastic) are the components of a typical weight belt. Divers can release the weight belt easily with one hand in an emergency.
Lead blocks have two slots to be able to attach to the weight belt. These blocks vary in weight. If a diver needs 9 kilograms, 4 of 2 kilogram lead block and 1 of 1 kilogram lead block can be used.
Plastic coated lead block are also used.
Free divers also use weight belts. However, a free dive weight belt is made of silicone that enables to tighten the waist of the free diver with the pressure increase.
This kind of weight belt has pouches. Lead blocks are placed in these pouches.
By this way, abrasion as a result of the lead block rubbing to the dive suit is decreased. Lead blocks don’t slip on the weight belt and results in derangement underwater. Because every pouch is stabled.
Instead of lead blocks, lead shots can also be used. You can find lead shot pouches and attach to your weight belt. Because lead shots are small rounded shaped, some divers with prominent hips may prefer.
Divers who are uncomfortable with a dive belt (usually because it hurts the hips) may choose to use a weight harness. Divers having problems with their back also prefer to use weight harness because it distributes the weight to a wider area.
Weight harness always reminds me the detectives carrying their guns under their jackets in the movies.
In fact, underwater models use weight harness to dazzle the weights under their dresses.
Handles in the system can be pulled to remove the weights in an emergency.
In most buoyancy compensator device, there are symmetrical weight pockets built in. Lead blocks can be placed here by the diver. Weights can be kept here without risk of falling by the help of a velcro and/or a clip.
Another design of BCD integrated weight system is the separate pouches. These pouches are generally have zippers. Divers unzip these pouches and place desired amount of weight in it. Pouches get zipped and placed in BCD. There are special pockets on the wings of the BCD. A handle is used to lock the pouches in these pockets.
These handles can be pulled in an emergency. When pulled, first the weight pouches get unlocked and when diver goes on pulling, these pouches are released.
There are also some other types of weights for divers.
Ankle weights, forexample, can be used to reduce the positive buoyancy of the fins and result in a better horizontal position.
V-weights are used in technical diving with two dive tanks. However, divers cannot remove V-weights in case of an emergency.
Tank weights can be attached to the dive tanks and move the mass (gravity) center on a desired point.
I have some suggestions to watch out buying a weight system
- buy plastic coated lead blocks if you are planning to buy a weight belt. This will reduce the wear of your dive suit.
- weight harness should only contain removable weights. A weight plate on the back can be a problem in an emergency when a quick release is needed.
- choose a BCD that gives you the chance for trim weights like weight pockets on the back if BCD integration is preferred.