When starting out snorkellers who want to leave the surface, freedivers and spearfishers all ask the same question...
"How much weight should I wear?"
The only correct answer is, "The safe amount for you."
For safety reasons, the single most important thing you must achieve is to be buoyant when you are on the surface. If you have applied correct weighting, you will remain on the surface, even after a full exhale, which is vital if a rescue scenario occurs and your buddy needs to keep you above water.
There are no formulas. There are no rules. The safe amount for you is determined by trial and error.
Leaving the surface to go underwater while holding your breath is called Apnea Diving. Whether you're a snorkellers, a serious freediver, or a spearfisher, you're apnea diving when you leave the surface.
Apnea divers wear lead weights to offset the positive buoyancy of their bodies and their wetsuits. To apnea dive comfortably, you need to use enough weight to help you descend to the point your lungs and wetsuit compress to the point you achieve neutral buoyancy. But not too much weight that you can't be buoyant on the surface.
There are several problems with being overweighted.
Everyone's body composition is different. Bone and muscle density, fat content, lung volume, height and weight all affect buoyancy.
It's a fact that most men are more body dense than women. A man's physique is generally more dense than a woman's and men generally have a higher muscle to fat ratio in their bodies. This means that men sometimes find they need no weight at all, e.g. snorkelling in the tropics, or in some cases need to add buoyancy to stop them from sinking when they exhale at the surface.
Then there is the depth of your diving, the water temperature, water salinity and water density. Salt water makes you substantially more buoyant.
Also there is the thickness, age and configuration of your wetsuit. A full length single piece 3mm wetsuit is less buoyant then a 5mm wetsuit, which is less buoyant than a 7mm wetsuit. But a two piece long-john style wetsuit, where the core body area is doubled in thickness, is more buoyant than a single piece wetsuit of the same thickness.
So, the only way to accurately determine how much weight you need is through trial and error. Buy a small number of weights to start. You can then rent or borrow some additional weight to finalise how much you need.
Begin with all your equipment in place while wearing an estimate of the weight you think you will need. Good starting points for an average-sized person will vary depending on suit thickness. A starting point could be:
Note: We are not suggesting the above are ideal weightings. They are simply a reasonable starting point.
Get in the water. Flood your wetsuit to ensure there are no air bubbles trapped inside.
Now lie prone (horizontal) on the surface. Now breathe out.
You want to be able to comfortably REST in a horizontal position on the surface.
If you need to use your hands or fins to stay on the surface or are sinking, take some weight off your weight belt or weight vest. If you're too buoyant on the surface, add some more weight.
Being comfortable at rest on the surface ensures you will remain there should you experience a blackout.
Perform this simple check every time you:
It will help you to better determine how much weight you need to dive. Your goal is to:
It's helpful if you bring an extra half a kilo out on your surface buoy to adjust your weight in the water. We recommend getting your weighting right to the nearest 0.5 kg (1.1 lb).
Your weight belt must have a quick-release or Marseilles buckle so you can:
Rubber weight belts will stay in place better than a nylon belt as you descend. When your suit compresses, a nylon belt can move a lot.
Cressi Elastic Marseilles Rubber Weight Belt - 140cm
RRP: $69, Our Price: $65.50, You Save $3.50 (5%).
This freediving/spearfishing/snorkelling weight belt is comfortable and streamlined. The high elastic properties of the belt will contract and compress with your body and wetsuit during your descent and expand and stretch as your body and wetsuit expand during ascent. This keeps your weight belt properly positioned around your hips. The heavy-duty 300 series stainless buckle is easy to use and lasts a lifetime.
Many spearfishers like to move some of their weights up onto their back using a Weight Vest for improved trim and an easier to manage weight belt. It's the initial duck dive from the surface that is crucial to success. Moving some weight up onto your back makes it much easier to get a better transition from the surface to depth. However, it's also essential that a weight vest also be easily dumpable. Many weight vests aren't easily released which is why freedivers typically don't use them, plus they are often not tight fitting, and create drag in the water.
Some experienced freedivers and spearfishers choose to use a Neck Weight (instead of or together with the weight belt). The neck weight helps to streamline the body, or to help with correct body positioning during free-fall in depth freediving disciplines. Strong neck muscles are needed when using the neck weight on the surface, which can be a concern for some divers as they feel it can affect safety.
The most important factor when purchasing or choosing your weight method is how quickly you (or your buddy) can remove it in an emergency situation, either under the water or on the surface.
Using smaller increment weights allows you to adjust your buoyancy more accurately. Weights in the 0.5 to 1 kg (1-2 lb) range are ideal. This will also more evenly distribute the weight around your body and allow for more streamlined apnea diving. It will also decrease your effort and increase your bottom time.
Land and Sea PVC Coated Dive Weight - 0.5kg 1.1lb
Our Price: $15
This PVC coated dive weight is the smallest and lightest we have available to go on a weight belt. These particular weights are designed for nylon webbing or rubber weight belts, however, you can also put them in most pocket weight belts.
This lead weight is the size most commonly used by scuba divers, snorkellers, spearfishers and freedivers. It's sized to easily fit all standard 2 inch (50 mm) wide nylon or rubber weight belts.
It is important to keep a record of the weight you wore under which conditions, along with what other apnea diving equipment you used. It is also useful to take with you an extra half kilo weight for your belt, and neck weights of varying weight, so you can be more precise when fine-tuning your weight setup. This can become an invaluable reference for future apnea dives.
Scuba divers looking to get their weighting perfect should read our guide Perfect Scuba Diving Weighting.