SSI is a recreational scuba diving certification agency. Dive operations around the world issue SSI scuba certifications from beginner to professional level.
SSI offers certifications in scuba diving, freediving, as well as technical diving with their extended-range courses, and even rebreather certifications. SSI schools around the world keep to certain training standards with flexibility in skill order during basic diver training. This means that if you get stuck on a skill, you can go back to it later. It is at the instructor’s discretion on which open water dives the mandatory skills are completed.
Once you hold your SSI diver certification, you can dive around the world by showing your certification. You will be limited to dive to your certification’s limits.
Has printed training materials in over 30 languages
How Do I Get My SSI Certification?
To get certified with SSI, you need to locate an SSI dive center and complete the SSI Open Water course. You will be given access to their electronic learning materials which you work through with your instructor. There are also confined water sessions as well as open water dives conducted as part of your certification.
What is the minimum age to dive with SSI?
The minimum age for an SSI dive experience as part of the ‘Scuba Rangers’ program is 8 years old.
The minimum age where an SSI certification can be completed is 10 years old with additional junior depth restrictions.
PADI is a recreational diving agency. The agency trains and certifies students to become members in both beginner and professional levels of diving.
PADI offers scuba diving, freediving, skin-diving (snorkeling), and technical diving courses. These courses are standardized around the world. This means if you undertake a PADI Open Water course in Australia, it will be exactly the same as if you took the PADI course in Thailand. This also allows you to split the course if you needed to. For example; you could do half the course at home, and the rest of the course while on a tropical holiday!
When you complete a PADI course and become certified with this agency, then dive centers will know your level of training and allow you to dive according to the agency’s limits.
You will need to complete this form prior to any scuba diving course with PADI. Please check with your dive center or instructor for more information.
How Do I Get my PADI?
To get certified with PADI, you can find a PADI dive center or a PADI instructor and complete a course with them. You will receive PADI materials, and work through several modules to be certified. These usually include some theory, confined water sessions, and dives in the open water.
What is the minimum age to join PADI?
The minimum age for a PADI dive experience such as a ‘Bubblemaker’ try-dive is 8 years old.
The minimum age for a PADI scuba diving course is 10 years old with depth restrictions.
The minimum age for a PADI Professional Member, such as a DiveMaster or an Instructor, is 18 years old.
Is a PADI certification worth it?
Getting certified as a scuba diver is important if you want to continue diving for safety and practical reasons. It allows you to dive in different places, whether locally or internationally. A certification with an agency means you have trained to a high standard, and know safety procedures if an emergency were to happen.
A PADI certification is a great one to have as it is a widely recognised and international dive agency. You could go anywhere around the world, present your certification card or email, and the dive center will know your level of training and allow you to dive.
Is it worth it?
Yes, in our opinion!
How to find my PADI certification number?
Lost your PADI certification card? Or maybe you have accidentally deleted the email confirmation. Never fear. Any PADI affiliated dive center or PADI Professional can search for you in the international PADI system using your full name and birth-date.
There are a few factors to consider when trying to determine a diver’s “crush limit”. The human body consists of up to 60% water, leaving 40% of body tissue. Air compartments surrounded by body tissue and the water percentile itself have different susceptibility to crushing. The easiest to crush are our air spaces such as our middle ear, sinuses and our lungs. So, how deep can you dive before being crushed?
In short, a diver can’t simply be crushed by the weight of water. Even at extreme depths. But why is that? Read on for more information on how deep we can dive before being crushed!
Human bone crushes at about 11159 kg per square inch. This means we’d have to dive to about 35.5 km depth before bone crushes. This is three times as deep as the deepest point in our ocean.
The 40% of non-water non-gaseous minerals and tissues such as salts, proteins, fats and lipids are virtually impossible to compress similar to water.
Let’s look at the most basic physics that determine volume changes with pressure in an effort to work out how easily a diver’s air spaces could be crushed. Boyle’s law states the linear relationship between depth, pressure, volume and density in water. For the purpose of this article we are assuming 1 bar for 10 meters of water.
See the Boyle’s law table below.
Depth
Surface
10m
20m
30m
40m
Pressure
1 bar
2 bar
3 bar
4 bar
5 bar
Volume
1
1/2
1/3
1/4
1/5
Density
1x
2x
3x
4x
5x
Because water is virtually incompressible we are focusing on the crushing of air spaces within our body first.
Scuba divers and free divers rely on equalising to prevent damaging their bodies. They compensate for static water pressure by adding equal gas pressure into their air spaces as the atmospheric pressure of the depth they are diving in. This prevents their air spaces from collapsing under pressure.
In order to answer, how deep can you dive before being crushed?, we are going to ignore the other limitations we face when diving to great depths. These include differential pressure (saturation and off-gassing), gas toxicity and narcosis to mention a few.
Getting Crushed With vs Without A Pressure Suit
Diving often requires some form of exposure protection to be worn in order not to get too cold. Depending on the suit worn a diver is subjected to variable degrees of crushing.
No Pressure Suit means that we dive with the water touching our body all around and we only need to equalise our own air spaces. A skin suit or wetsuit won’t change this. The only way this diver will be crushed is when the water in the diver’s body solidifies. Otherwise as long as the diver is able to equalise their air spaces with gas, they prevent being crushed.
A Pressure Suit traps a gas bubble around the diver underwater. To prevent crushing, divers need to ensure gas pressure inside the suit is equal to the water pressure outside the suit. Dry suit divers learn to add gas to their suits as they descend in order to prevent “suit squeeze”, a very painful side effect.
If suit pressure drops, the decrease in gas volume inside the suit would crush the diver. Commercial divers double check their non-return valve before their dives. Failure of this valve in the event of a gas supply failure would create a vacuum inside the suit crushing the diver. At great depths, high pressure would completely crush the diver. At lower pressure however, the diver’s lungs would collapse still resulting in a death by crushing.
An Atmospheric Suit is a hard suit able to withstand the pressure of the surrounding water on its own. The gas inside these suits is at 1 bar (same as our atmosphere). By being rigid, the water will not crush the diver inside these suits. John Lethbridge first conceptualised the atmospheric diving suit in 1715. The depth limits of these suits is currently around 700 meters. Venturing beyond these suits’ maximum operating depths has the potential to crush the diver in the event of a suit failure.
Can Pressure Turn Water Into A Solid?
We all know solid water as ice. A gas turns into a liquid if cooled enough. In turn, a liquid turns into a solid if cooled enough. This is how we turn water into ice. So, freezing a human would kill them, however, that is not technically crushing them and not what we are looking for.
Kinetic-molecular theory determines the effects of temperature and pressure on liquids.
As mentioned above it is theoretically possible to cool any liquid to arrest particle movement, making it a solid. Since we are not looking for when a human freezes, let’s look at pressure. It is theoretically possible to apply enough pressure to a liquid to restrict particle movement enough in order to turn the liquid into a solid. Water is rather incompressible. Solidifying water requires immense pressure. This amount of pressure does not occur in any diving conditions on our planet.
If the water pressure was high enough in order for water to solidify under its own weight, we would be unable to submerse ourselves or dive into such water. Similar in that we can’t go diving in ice.
The deepest point in our ocean is just on 11 kilometers. Since the water down at those depths is still liquid and not solid, there is not enough depth in our ocean to solidify water simply with pressure. Water remains a liquid at even 1101 bar or pressure. The human body would therefore not solidify under that pressure.
How Much Water Pressure can the Human Body Take?
As established above, the human body is 60% water. Earlier I mentioned how bone crushes at about 11,159 kg per square inch which is not achievable by diving on earth. Our other body minerals and salts are virtually incompressible along with water. In theory as long as a diver equalises their own air spaces or that of the suit they wear, they avoid being crushed. There is no body of water deep enough to exert sufficient pressure in order to solidify water or compress salts, proteins, fats and lipids or even to crush bone in our atmosphere and gravitational field.
Diving depths have always intrigued people. Non-return valves failing and crushing divers in early pressure suit diving further highlighted this fear. How deep can you dive before being crushed therefore can’t be answered definitively. Achievable depths with SCUBA, freediving, and even commercial diving, are not enough to crush a diver. Phew!
Please note; this review was not sponsored at all. However, since posting this article the owner has now reached out to me based on my review and offered to go into partnership with myself and Down to Scuba. To help out my free diving blog, please quote Emma and Down to Scuba when booking your trip on The Junk or the Phinisi. This is of no extra cost to you but helps me continue writing my blog!
Review of The Junk Liveaboard in Thailand
Recently, I was lucky enough to get on a chartered liveaboard with some close friends and ex-colleagues. The Junk had been on my liveaboard wish-list for a while; the history of the boat, the old-timey vibe, and of course, diving somewhere new was very appealing. So did it live up to expectations? Have a look at my review of diving on The Junk liveaboard in Thailand!
History of The Junk Liveaboard
The Junk is an unusual name for a liveaboard but it refers to its history as a type of Chinese sailing boat. Junks were so named during the colonial period to refer to boats that used fully battened sails and were used as cargo ships, pleasure boats, or houseboats.
The Junk Liveaboard. Photo by Robert Horrion
This particular boat, the June Hong Chian Lee, was built in Penang, Malaysia in 1962. It is 30 meters, 140-ton three mast junk with 330 square meters of sails. The boat sailed from Burma to Malaysia carrying charcoal in its early life, before becoming a party boat around Phi Phi islands, then becoming a diving liveaboard in 1997.
Boat
The boat is super cool in photos with its massive sails up, and beautiful teak wood construction. I say ‘in photos’ because unfortunately, but understandably, it is a big job to unfurl the sails and put them up each time. Which is why it is not done often.
It has been fully modernized inside with a comfortable lounge area where we had all of our dive briefings, and where the food and drinks are served. There is air-conditioning in here which was a nice relief from the hot Thai heat outside.
We had 20 guests on our chartered trip, and it was comfortable enough without falling over one another. There is a huge table outside for eating and chilling out. Then a top deck to catch some sun (just make sure you don’t sit in front of the captain’s eye-line otherwise you’ll block him from driving the boat and he might yell at you!), and another top deck with sun-loungers and beanbags. During the day, the crew will rig up a big shade over the huge table and sun-loungers to beat the sun.
Logistics
We received a very thorough briefing of the logistics before our first dive. This was clear and informative so everyone knew what they were doing and when.
The setup area for diving is outside on either side of the boat with numbers for each diver. You get a numbered tank rack, a numbered crate for your bits and bobs, and 2 numbered pegs to hang up your towel, wetsuit, belongings. They also put that number on a sticker for your fins. This is used so that you don’t mix up your fins (if everyone is wearing the same Scubapro Jetfins – which happened on the last liveaboard I went on!).
You will be put into groups with similarly experienced divers and be given a dive guide. Each group will get ready on the boat before moving onto a rib (Rigid Inflatable Boat) to get dropped off over the dive site. Your fins will already be on the rib (which is why the numbers make it easier).
On the rib, you will put your fins on, and when the driver tells you it’s ok, you will backward roll-off all at the same time into the water.
The diving groups entering the water are staggered, with about 5 minutes or longer in-between each drop-off. The rib driver and dive guide might also decide on different drop-offs which is great so you don’t have to see too many divers in the same spot.
The order of the diving groups are rotated each day, but stay the same for the day. This allows everyone to either be the first group in the water or the last group to enter.
There were also big tubs to rinse off your smelly wetsuit (I mean, c’mon, we all do it..) which was rinsed after each dive. There was also a freshwater tub for cameras, computers, torches, and masks.
The highlight after each dive was the ‘hot shower’ from a giant ceramic jar with fresh water. The water was heated up from the sun and we all lined up after the dive to get a bucketful of hot water poured over us. It was delightful!
Dive Sites
Our 4-night stay on The Junk liveaboard took us to the Similan and Surin Islands around the west coast of Thailand. Our first dive was a check dive to gauge everyone’s experience, determine the number of weights you needed, and to ensure everyone could put up a Surface Marker Buoy (SMB). We visited the main dive sites, Koh Bon, Koh Tachai, and the famous Richelieu Rock during our trip. The location for our dives changed a bit depending on the conditions, but this was always communicated to us. Some of the dives included:
Elephant Head Rock.
Elephant Head Rock
There are three large boulders rising out of the water, with one boulder on the surface with a hole that looks like an elephant ear. Loads of submerged boulders that have created cool swim-throughs and sheer walls. The bottom is around 35 – 40 meters. I loved this dive with its medium current, visually stunning valleys and cool swim-throughs. We also saw so many giant moray eels hiding in the rocks, and also spotted some bright blue ribbon eels. Unfortunately, I had a horrifically foggy mask!
Lucky for dive buddies!
Koh Bon
Koh Bon has an opening on the surface of the rock where you can see through to the other side. Boats will usually park in the bay which protects from the wind and waves. We spent the night moored up here. The western ridge has a cleaning station for mantas, but unfortunately, we had no mantas during our dive, but they are known to be around, especially with the strong currents on this dive site. This seems to be a large dive-site and we were dropped off at different places for several dives. Really nice with lots to see. I believe we were aiming to dive Koh Bon Pinnacle, but with the low visibility, our plan changed. This Pinnacle is apparently quite a deep dive, with the top starting at 18 meters.
RIB ride around Koh Bon.
Koh Tachai
Koh Tachai is located about 20 km north of Koh Bon. This island has a beautiful white sandy beach that we were not allowed to go to as the princess had recently shut it to the public, but it looked awesome from afar. We had a dive at Twin Peaks (Koh Tachai Pinnacle) which is about 500 meters away from the main Koh Tachai island and consists of two submerged pinnacles.
The south pinnacle is bigger, and about 12 meters from the surface. It is surrounded by large boulders, and the sandy bottom is around 30 to 45 meters. There are swim-throughs on the west side and the east side has smaller rocks, covered with hard corals. There are colorful soft corals and large sea fans. The north pinnacle is about 50 meters away and the top of the pinnacle is 18 meters from the surface.
Manta rays and whale sharks can be seen here, along with whiptail rays, whitetip and blacktip sharks, and schools of barracuda, snappers, and fusiliers.
Richelieu Rock
This dive site is the big bananas of the Andaman Sea, and the highlight of the diving trips out here. Some claimed that Jacques-Yves Cousteau found this dive site, but this has been recently disputed, and it is more widely accepted that Richelieu Rock was named after Andreas du Plessis de Richelieu, a Danish officer who became the first and only foreign-born commander-in-chief of the Royal Thai Navy. He was the first person to complete a hydrographic survey of the Andaman Sea including the site of Richelieu Rock.
The rock itself is horseshoe shape, with a mooring line on the south-east. The top of the rock is hidden in high tide, and can be seen in low tide. It is a pinnacle with a bottom depth of 35 meters. The south side (inside of the horseshoe) slopes down gently with sea fans and bright corals, while the rest of the pinnacle consists of steep walls and groups of rocks.
The marine life is stunning here, and it’s also where we spotted the whale shark on the east side! There were some giant harlequin shrimps (my absolute favorite) munching on starfish legs, quite a few seahorses (biggest ones I’ve seen), schools of giant trevallies and snappers, lots of nudibranchs, tiny and gigantic scorpionfish and more.
The current wasn’t super strong here. But if you do have ear troubles or you’re without a guide, you will probably want to descend on the mooring line in case of a current. The dive site can get busy, but we did 4 dives here and two of the dives we were alone. Amazing dive site; lots to see and experience, despite the low visibility on our dives!
Richelieu Rock dive map. Map by Pocket Divesite by Vacation in Design. 2006
Equipment
Most of our group took their own dive equipment, but some people did rent equipment on board. There were spares of BCDs, wetsuits, regulators, lots of SMBs, lots of torches, various masks etc. It was well-stocked, and the quality of the equipment seemed quite good.
We used enriched air (NITROX) on all of our dives. The head equipment guy came around to each diver with an analyzer before every dive so that we could analyze and check our own nitrox tank.
Accommodation
You can choose double/twin share, a triple berth, or a 4 person room. Each room has air-conditioning and an en-suite bathroom with hot water.
The rooms are a little dated but keeps in line with the traditional old sailing boat theme. It’s clean and a crew member comes and makes the bed each morning during your first dive. The bathroom is a bit old but usable with a good amount of hooks and racks for your toiletries and towels.
Food
I’ve never been on a liveaboard with bad food, I don’t even think that exists, and The Junk certainly did not disappoint. We had eggs, bacon, sausages, potato hashbrowns, and rice soup options for breakfast. Various lunch options including papaya salad, green curry, pad-thai, laab, chicken popcorn, and salads. Snacks like fried bananas, muffins, sticky rice and mango dessert, spring rolls. And dinner options which included curries, pork belly, and everyone’s favorite, spaghetti bolognese. There were also vegetarian options and a steady supply of fruit.
There were also a few seafood options (prawns/squid/fish in curries), and I always feel a bit weird about this one. I could go without seafood on a liveaboard, especially since we’re there to dive with the marine life, but I also ate it since it was on the table. I know people coming from overseas might be keen to try the Thai seafood curries so this is probably why it is an option but if I had a liveaboard, I would not have it on the menu.
Soft drinks, tea/coffee, and electrolytes for your water were free of charge. Thai beers are stocked up every day for after your last dive, and these were a reasonable 2.50 USD per can. You could also buy a bottle of wine for 27 USD.
Outdoor hangout area on The Junk. Tank racks are on either side.
This gave us a good amount of ‘chillaxing’ time to nap, read a book, play a game of cards, etc. after eating and before the dive!
Crew
Again, I’ve never come across crew that are not competent on a liveaboard. The Junk’s cruise director, Marco, was knowledgeable and knew his stuff. He was serious about safety briefings and was approachable when I had a question about the dive sites or marine life. He knows how to dive these locations, and knew where to find the macro life. The other dive guides were great too, with various experiences, and were helpful with logistics, and stories about the diving.
The rib drivers, equipment guys, cooking and cleaning staff, were all very polite and helpful. They were quiet (except when preparing breakfast at 5 am, that’s when they were yelling/talking to each other. Haha) The Captain was a smiley guy, which is a nice change from some captains who can be grumpy!
Vibe
The Junk liveaboard is a relaxed trip. The locations for the dives were interchangeable depending on the conditions, and the schedule each day was written the night before to give you time to prepare (and to work out how many beers you would have depending on the wake-up time the next day!).
I’m very good at relaxing on a dive boat
There were some ground rules for the boat, dry areas, not to charge electronics inside rooms, but they were very easy to stick to.
It was easier for our group as most people already knew each other, but I found there were enough areas to relax in depending if you wanted to socialize, or if you wanted some alone time to tan and read a book. Several people just went to their rooms during the dives to make the most out of the air-conditioning, or to get another nap in.
Wake up calls was a small bell that they rung outside your door in the morning, and the briefing calls and meal times (very important!) were indicated by a massive, and very loud, bell that yours truly was allowed to ring one time!
Safety
We had a very thorough safety briefing when we got onto the Junk liveaboard. The cruise director was clear explaining safety procedures and got us to do a fire drill with life-jackets. The Junk has a tremendous amount of power points in the lounge area for charging phones, laptops, torches etc. and we were asked not to plug anything in the rooms due to the possibility of fire, which we all know can happen on boats.
Getting onto the rib from the big boat was easy with the help of 2 men on the platform and 2 men on the rib. But getting into the rib after the dive was a little harder with the small ladder. I would imagine this can be difficult in waves.
My Diving Experience
I have reviewed the diving last as the conditions of the dive-sites is not a reflection of The Junk liveaboard. Unfortunately, we did not have the most amazing diving conditions as visibility went as low as 1-2 meters on some dives. We did, however, see a whale shark (I spotted it first!) at Richelieu Rock so of course, that made it an amazing dive.
There were currents on some of the dives, and while we did have to work a bit, and kick against it, most of the dives were comfortable for experienced divers. Nothing like the up and down currents when diving in Komodo or Myanmar!
The conditions on the surface were favorable. We had little wind, flat seas, and no rain. It was so pleasant that a few of us slept on the top deck under the stars.
The diving in the Similan and Surin Islands has a wonderful range of marine life and bright corals. I know the diving can get crowded at times with a large number of boats on each dive site, but we were lucky to have only spotted a few other boats during our trip. The dive sites can usually be catered to different experience levels, with some people going for a drift dive in the current, and some groups sheltering from the currents, so there’s something for everyone.
The Lowdown
Boarding The Junk liveaboard and spending a few days and nights was a fun experience. You will find all the modern comforts of other newer liveaboards but you will be hard-pressed to find another boat with the charm of The Junk liveaboard. From the history of the boat to the materials used in the construction, there is no other boat like it. The dive logistics on the Junk liveaboard were smooth and professional, with a friendly and smiling crew. My favorite thing on a liveaboard is having lots of places to hang out, whether it’s in the sun or in the air-conditioning, and The Junk Liveaboard certainly delivered!
For the best price on The Junk liveaboard, send me an email or message on FB and I’ll put you in contact with the owner!
Finding the right number of weights for your dive can determine whether you have a great dive or a disaster of a dive. If you realize you have the wrong number of weights after jumping into the ocean it can be annoying or even dangerous. You will need to consider a number of factors to know if you are properly weighted for diving and learn how to make a weight belt for diving. Luckily as a beginner, instructors will often carry a couple of extra weights for you as they help you figure out your imaginary scuba weight calculator for that perfect diving buoyancy!
In this article, we will explain everything you need to help you determine the correct number of weights for your dive. This post aims to help you plan your weights before jumping in for a dive and be able to confidently say I know I am properly weighted for scuba diving if I..!
I know I Am Properly Weighted for Scuba Diving if I Do a Buoyancy Check!
Of course, there is one definitive way to determine if you have the right amount of weight – a buoyancy check on the surface. However, this should be done with a steel tank or an aluminum tank that is nearly empty.
There are 6 simple steps to a buoyancy check on the surface:
1. Get fully kitted up and wear your best guess at the weights required. Base this either on a weight calculator, or from previous experience, or the recommendation from your guide.
2. Enter the water and inflate your BCD on the surface.
3. Take and hold a normal breath of air – THE ONE TIME YOU WILL EVER HOLD YOUR BREATH.
4. Empty your BCD completely and allow yourself to sink.
5. If the water level sits at eye level while holding that normal breath of air in your lungs, then descend when you exhale. This means you are correctly weighted!
I know I am properly weighted for diving if I do this buoyancy check!
6. If you are sinking while holding that normal breath in your lungs, then you are overweighted and are using too many weights. Try taking off some weights.
If you are floating on the surface and cannot sink to get to eye level with the water, then you are underweighted and do not have enough weights. Try adding a weight.
We would also recommend doing this same check post-dive, with a near-empty tank. This will give you a better indication of the correct amount of weights needed with a more buoyant tank.
How do we know how many weights we need?
The number of weights to wear depends on a large number of factors. These include:
Type of Water – salt is more buoyant than freshwater
Tank Material – Aluminium tanks will start off negatively buoyant but will become positively buoyant as you consume the air. This means you will need to account for the buoyancy change during your dive. Steel tanks, however, will remain negatively buoyant through the dive.
Weight of the Diver’s Body – larger people generally require more weight though if you have a lot of muscle mass, then this is denser and will sink easier.
Body Fat Percentage – Fat is more buoyant and floats, so people with more body fat often float on the surface easier.
Type of Clothing Being Worn – A full-body 5mm wetsuit will be a lot more positively buoyant than a string bikini. A dry-suit will be even more buoyant.
Experience – Experienced divers with developed breathing techniques can reduce the number of weights required
BCD – Different BCDs have different lifting capacities. This affects the amount of weight required.
Regulators – Even your regulator can have an effect on weighting. Heavier regulators and 1st stages will help reduce the amount of weight required.
Does a SCUBA weight calculator exist?
Some people have tried to produce mathematical calculations on how much weight you should carry. In recent years mobile apps have appeared to claim to be a scuba weight calculator. After entering all the parameters, they will give you an estimate of how much weight you should carry.
While tools such as these sound perfect, they are still no replacement for experience. Every time you dive, you should make a note of how much weight you used and what you were wearing. Take note of the conditions too. For regular divers, it will quickly become second nature and you will naturally select the required weights based on your equipment configuration that day. For the occasional leisure diver who only dives once a year however, calculation apps provide a good starting point that can be adjusted from thereon. If in doubt, always ask your instructor or divemaster for their assistance, as most professionals can give you a calculated guess based on your body shape and equipment.
What if the weights are wrong?
At some point, everybody gets it wrong. Too many weights may increase your drag and air consumption as you try to compensate for it by adding extra air to your BCD or breathing in to float. But being ‘over-weighted’ will generally not cause a big problem. Not enough weights, however, can make your dive very uncomfortable and possibly dangerous.
If you notice that you have a lot of difficulties descending at the start of your dive, then the safest thing to do is to either abort the dive or go back to the boat to get more weight. This is important as you also want to make sure you have enough weights to be neutrally buoyant during your safety stop at the end of your dive.
The main issue with being ‘under-weighted’ during your dive with an aluminum tank is if you end up making a rapid or fast ascent to the surface. As you dive, your tank will slowly start to pull you up. Usually, you will release some air out of your BCD to counteract the positive buoyancy. However, if your BCD is completely empty and the tank is pulling you up to the surface too quickly, then you may have a risk of Decompression Sickness (DCS) or Lung Overexpansion (LOE).
DCS is caused by going up to the surface too quickly without allowing the absorbed nitrogen to escape from your body, while LOE is caused by accidentally holding your breath as you go up. Figuring out that you are under-weighted during a dive can potentially be stressful leading to dangerous situations.
Conclusion
Modern diving techniques and equipment require you to be correctly weighted. If you are overweighted, you will be diving inefficiently and will struggle to stay off the seabed and coral. This will lead you to waste air. If you are underweighted, you will struggle to descend and may find yourself constantly swimming down to stay underwater. This will also lead you to waste air.
Choosing the correct amount of weight is therefore vital. Regular divers will instinctively know how much weight they require that day. The occasional diver, however, should make an effort to record in their logbook how many weights they used on a dive, what they were wearing (rashguard, wetsuit, or drysuit), and if they had any problems being over or under weighted. While you may see it as hassle writing such comments in your logbook, you will be thankful 6 months later when you’re preparing to go diving again.
However you do it, take weighting seriously and don’t be scared to ask for more weight or abort a dive if you are incorrectly weighted. Your journey to perfect buoyancy is wholly dependant on correct weighting, so treat it as important as any other pre-dive preparations.
