Browsing Tag dive gear
Do I always have to wear a full length wetsuit?
A common question that we normally get is whether a short wetsuit (up to the knees and elbows) or a full length wetsuit (up to the wrists and ankles) would be more suitable for tropical waters. New students in warm tropical waters (28 to 30C) like to ask for a short wetsuit, because it’s much easier to put on. However, I would always suggest wearing a full length wetsuit, despite the temperature.
The big reason for this would be protection against scratches and bites in the water, even though the temperature may not warrant it. Another good reason would be thermoclines, which is water at a different temperature at a different depth. Normally the temperature would drop the deeper you go, and this can’t always be predicted in advance.
As divers get better and more comfortable in the water, they also tend to move less, and eventually get to the point where they are able to stop moving completely. At this point, because the body isn’t working so hard, a person will lose body temperature faster, and result in a colder dive.
My recommendation is thus to always dive a full length suit, and if you’re thinking of buying a suit, then always buy at least a 3mm suit, you’ll find more use for it in a wider range of temperatures than a short wetsuit.
| Short wetsuit | Full length wetsuit | ||
| Pros | Cons | Pros | Cons |
| Easy to wear | Gives you a funny looking tan | Protection against scratches | Harder to put on |
| Cheaper to purchase | Potential scratches and bites | Keeps you warm in thermoclines | More expensive |
When to deploy a surface marker buoy (SMB)
The answer might seem obvious, but many divers neglect to shoot the bag early, and end up surfacing a long way away from their dive location and their boat. I’ve heard many stories of divers drifting for hours because of their boat crew could not locate them. Don’t let that happen to you.
I would always consult the diving conditions when deciding when to deploy my surface marker buoy. Generally, you should shoot the bag when you are starting the ascent in a normal dive, or whenever you are leaving the reef, whichever happens earlier.
However, if the conditions are bad, such as when there’s a strong current pulling you away from the reef, then you would need to deploy your SMB as early as possible before you get swept into the open ocean. Don’t delay getting the SMB to the surface!
Consider a situation where this wasn’t the case, for example, if the diver ascended to a safety stop before deploying the SMB, or in a situation where the spool wasn’t long enough to reach the depth the diver is at.
In these situations, the time taken to ascend to a shallower depth, coupled with the current, could mean that the diver drifts far away from the dive site. Given that the boat would be waiting for the diver to ascend near or on the dive site, this could mean the boat captain will not be looking out towards the ocean where the divers eventually surface.
Needless to say, it’s much harder for the boat captain to spot divers floating in the open ocean than next to the reef. Personally, I wouldn’t take it on faith that the boat captain will always know where to look for you when you surface. Do your part as well to guarantee that he can see you!
Finally, if you’re wondering whether to use an inflated SMB throughout your dive, read this article that discusses it in depth.
Differences between a jacket and a backplate and wing system
Looking at BCD systems and their merits will require an understanding of what they are there to do while you are diving. Obviously, a BCD is there to help control your buoyancy, but in terms of function, how does this actually work?
All BCDs have a way to inflate and deflate the air bladder. More gas in the bladder equals more positive buoyancy, and less gas equals less positive buoyancy. Simple!
However, how these devices are built and designed play a huge role in how easy it is to manage the gas within the BCD, and thus manage your buoyancy as a result.
Let’s look at jacket BCDs, which are the most common type of BCD found in almost every dive centre the world over. This is shaped like a vest or jacket, with arm holes and an air bladder that goes from the front to the back, with additional pockets and clips and adjustable straps for convenience.
The backplate and wing system, is a completely different looking piece of equipment, with a 5 point harness and crotch strap, attached to a rigid metal or plastic back plate, which in turn is bolted onto a round donut shaped air bladder.
Functionally, both types of BCD will allow inflation of gas into the air bladder through the inflator mechanism, and both will allow deflation of the gas from either the deflate button, or one or more dump valves.
However, the relative positions of the dump valves, and how the gas moves in the air bladder plays a critical role in how the BCD performs while diving. Ultimately, we need to know where the gas is located in the bladder while underwater, and that is how we can use these devices effectively.
Now if we can agree that a good diving position in the water would be a flat, horizontal trim to aid in streamlining, then where would the gas be in the BCD in that position? In a jacket BCD, the gas would be at the top, near where the tank strap is. Depending on the exact trim of the diver, this gas can be near the shoulders, or near the bottom of the tank. There could also be some gas trapped in the front pocket areas as well.
Most new divers learn to dump gas from their BCDs by extending the inflator hose upwards and pressing the deflate button. The diver would need to come into a head up position, to allow the gas to flow to the deflate button to be released.
This additional movement is not ideal, firstly because in that position, the diver would then need to come back to a horizontal position again, wasting energy and effort to move into and out of position.
Secondly, if the diver was in a runaway ascent, the best way to mitigate that would be to position head down and kick downwards, which would be really hard to do if the diver is angled upwards with their legs beneath them. Any additional movement in the legs would only exacerbate the problem by bringing them closer to the surface and causing the gas in the bladder to expand more.
Let’s contrast this with a backplate and wing system. While diving, the donut shaped wing will fold upwards, and wrap the tank on both sides. The gas in the bladder in this position then can only be in one position, at the highest point of the wing on both sides of the tank.
In this position, getting the gas out is relatively easy, as the dump valve on the wing is located near the bottom of the wing and close to the top edge. In most cases, the diver would not need to adjust his trim by a lot in order to remove the gas from the wing. He would just need to pull on the dump valve string upwards, trapping the gas between the dump valve and the tank. In this case, there isn’t anywhere for the gas to travel to, and will be easily dumped from the BCD.
BCDs should also minimize the amount of trapped gas that cannot be removed from the bladder, in terms of corners which can create pockets of gas that are not easily moved to the dump valves. The dump valve position should also allow for the maximum amount of gas to be removed from the bladder, so that every bit of gas is removed and won’t cause any additional positive buoyancy due to gas expansion on ascent.
If those are the key traits that make for an ideal BCD, then I feel a wing design makes the most sense. It’s round and doesn’t have any corners to trap gas, has a smaller internal surface area, the dump valve is located close to the edge of the wing, and it’s design prevents catastrophic failure in the event of a dump valve breakage.
The backplate system also has other benefits in terms of fit and streamlining, which ultimately leads to better control in the water.
BCDs these days come in all types and flavours, but choose wisely! It needs to be effective in the water, and not cause any additional complications.
Choosing the best surface marker buoy (SMB) for your dive
Surface marker buoys are handy for a number of occasions, whether it’s to signal your position to your boat at the end of your dive or during emergency ascents.
When you need immediate help or when someone in your dive group needs to get to the surface quickly, you’d want to be able to deploy the bag without it causing other problems or making matters worse. That’s why choosing a suitable SMB for your dive is so important.
There are three main factors a diver should consider when choosing a surface marker buoy: its size, method of inflation and the length of its line.
- What size do you need?
To be useful, the marker must be visible on the water’s surface, so it should be as large as you can manage. My emphasis is on what you can manage. You could have the largest marker on the planet, but if you can’t inflate it properly, it would simply be a limp piece of plastic floating on the surface. That certainly won’t be noticeable from a distance — unless the boat crew is consulting Google Earth.
Therefore, the size of the SMB you choose should be the largest that you can reliably fill from depth. Personally I prefer a smaller, thinner bag that will stand upright when filled with a relatively small volume of gas. I use the Halcyon 1m SMB on all my dives. This bag will fill up completely with only a single regular breath at a depth of about 10m. If you are at a shallower depth, then you’d need to blow in a larger breath of air, but it’s definitely still possible to fill up the bag quickly and send it on its way without much stress.
Now you might be wondering, what if you’re diving at sites with large waves and surge? Wouldn’t a larger (more visible) surface marker be better? In response I would ask: Is the dive worth putting yourself in such a situation? If the answer is yes, then make sure you are prepared for it with a larger surface marker.
Remember that a larger bag must be filled with a greater volume of gas in order to stand upright on the water’s surface. This means you’d need to either blow more gas into it (by exhaling or purging from the regulator) or release the bag when you are at a greater depth to allow for more gas expansion. The latter would be a good option, but the downside would be the much longer line that you would have to reel in as you ascend.
I would normally only inflate these larger surface markers once arriving on the surface and the boat is further away. The bigger marker will be easier to spot from a distance, but will also be harder to manage while underwater.
- Which method of inflation should you use?
Open circuit SMBs are some of the commonest in the market. To inflate an open circuit SMB, a diver typically purges air from his alternate air source into the bag. However, I do not recommend this method of inflation for a number of reasons.
The large amount of air purged from the alternate air source would likely cause a fairly significant and sudden buoyancy change. In an emergency or stressful situation, a sudden change in buoyancy could easily spiral out of control.
The force generated by the large volume of gas also means that the SMB will take off towards the surface really quickly. If the diver does not manage the line well, the line could get tangled with the BCD or tank, and drag you up to the surface. Nobody wants to be a human SMB!
I would always opt for the oral inflation method, because it is quicker and safer. The amount of gas that you exhale would not cause a significant buoyancy change (unless you inhale an extra-large breath of air right before). This makes the buoyancy change much more manageable. You wouldn’t need to find your alternate air source, too.
If like me, you prefer the oral inflation method, what’s left is to choose an SMB that works best with it. It’s possible to orally inflate an open circuit SMB, but due to the line being attached near where the open end of the SMB, there is a higher risk that your regulator might get caught in the SMB line or the SMB itself. Definitely not my first choice.
There are many SMBs on the market that are designed for easy and effective oral inflation. They normally have an oral inflator with a one-way valve. This, in my view, is the best one to use because it guarantees that the gas goes directly into the SMB. It’s also really easy to use. The Halcyon SMB I use does not have a locking mechanism, so you won’t need to fiddle with extra bits to inflate the bag.
- How long should the line be?
Some SMBs come with a 5m line, which means you can deploy the SMB only at the 5m safety stop. Obviously this is limiting, as you might run into other situations where you need to deploy the SMB at a greater depth. My advice: Always get a longer line that’s wound around a spool.
SMBs do not always take a straight path up towards the water’s surface, and might ascend at an angle when there is a current. As such, always make sure your SMB’s line is longer than your deepest planned depth. This means that if you are doing a 30m dive, then a 30m spool is not going to be sufficient. A 45m spool would be a better choice. I would use a 30m spool for dives to depths shallower than 25m.
In summary
My recommendation is to get a small thin SMB that you can reliably fill via oral inflation, and use a spool with an appropriate amount of line. Also, remember to practise deploying your SMB after buying one! A seasoned diver can easily get a bag deployed in less than 15 seconds, so keep practising until it becomes second nature!
How do I attach a bolt snap to diving gear?
Attaching bolt snaps to dive gear like SPG hoses, regulators and backup lights makes for easier stowage. Now the question is: Should you use cable ties or nylon lines?
For me, the choice depends on where and how they will be used. Nylon lines are definitely superior to cable ties in most situations, however, they take some practice in order to be tied correctly and securely. Cable ties are quick and easy to secure, and are found everywhere, so they are a quick handy solution to connecting a bolt snap when you’re out diving.
Let’s dive in to the various situations in which either of these options might be suitable.
Attaching bolt snap to SPG hose: Cable tie
A bolt snap attached to an SPG hose with a cable tie.
The connection between the bolt snap and the SPG hose tends to be a static tie, that is, it would not move much in the course of its lifetime. The clip on the SPG hose need only flip forwards and backwards, and there would not be much turning along its vertical axis.
For static connections, a cable tie would be sufficient. A cable tie has strength along the length of the plastic tie, but does not handle rotational forces well. If a connection has a high possibility of rotating or turning sideways during use, then a cable tie is not ideal.
Attaching bolt snap to long hose or backup lights: Nylon line
The long hose is traditionally tied to a bolt snap with a knotted nylon line.
The long hose connection occasionally has some rotation, but will not be excessive. Likewise for backup lights, there might be some movement when they are clipped on. A cable tie is generally sufficient, but a knotted nylon line connection is definitely superior.
An SPG hose can also be tied to a bolt snap with a nylon line. This particular knot is probably 4 years old now.
The backup light should be tied with a nylon line connection to be secure.
Attaching bolt snap to backup lights, cameras and other large equipment: Nylon line + Cable tie
Due to the way the camera housings move in the water when clipped off, an extra cable tie over the knotted line is a good idea!
Alternatively, make sure your line is thick and tied really well! You wouldn’t want to lose a few thousand dollars worth of camera equipment due to a failed knot!
Connections to large, bulky or heavy equipment will certainly have rotational forces involved. Picture your camera dangling from the bolt snap attached to the D-ring of your shoulder straps. The weight will cause your gear and its connected bolt snap to sway in various directions as you move, and when your hands are busy with something else. The equipment will also rotate as you clip on and off. So, for a camera and other heavy equipment, I would say a knotted line is mandatory. I might even put a cable tie over it to be doubly sure that the connection is secure!
Looking at the camera housing when it’s clipped off to a d-ring gives you an idea of how it will move and swing when diving. I’d rather make this connection a secure one!