Movement
Posted: September 13, 2011 Filed under: Foundational, General Leave a commentI call it this because the final two foundational skills are related to movement. Breathing and buoyancy are in play at all times when we dive. If we are stationary, these two pillars of Precision Diving have the largest impact. Diving being active, we do not sit still all that often and when we do it tends to be for short periods.
The final two pillars of Precision Diving are all about movement. This is why I present them together. Swimming and trim are the cornerstones of our movement as divers. Swimming is how we actually create the movement. Trim is how we control how the water moves past us. Or how we move the water out of the way when we move through it. Of course, breathing and buoyancy need to be ideal and are in play as well. But, the choices we make in how we move, position ourselves, and configure our gear has big impacts on our performance while we dive.
Most divers learn to flutter kick. There is nothing wrong with that. I do wonder why it stops there with most new divers. There is nothing preventing an instructor from working on more than one way to use the fins. Well, perhaps motivation and a bit more time. But, if you are a new diver or about to become one, demand to learn more than one way to kick/propel yourself. It is important and it will serve you well to learn this early and have the choices be automated early for you.
Precision Diving is not about one type of gear or one style of anything. This holds true for fins. A good diver should be able to use any fin. The choice of what is good is a very individual thing and should be done through trying many out and then making the choice for which fin best suits your needs and diving. You may find that you choose more than one pair of fins for different activities.
I use different fins for daily diving then I do for cave diving. I use another type of fins when I freedive and even sometimes use a monofin. So, select fins that work best for the performance you need out of that tool when and where you need it.
Of course, when you are new, you need to start with something. So, this is where is pays to have a good relationship with your instructor. Make sure you have a good conversation about what type of diving you plan on doing and where you plan to dive. Once your instructor fully understands your needs, then you can consider their recommendation.
Fins are important. They are the engines by which we create our movement underwater. Invest in something good. Fins tend to last a very long time and most people do not buy new ones because they wear their fins out. Usually new fins are purchased because there is a new feature someone wants. It is important to make sure the fins suit you and your diving. In spite of what some say, no one pair of fins works for everyone in all applications. Those that disagree, I am very happy that you have found something that works so well for you personally. However, this is not true for all.
A fin that is too stiff can cost you more energy and create more work for you if you are not prepared to use them. This will take bottom time away and you will consume more breathing gas. This is not optimized performance and not Precision Diving.
Some fins may be too negatively buoyant for your body composition. This will cause your feet to sink and you will need to make other compensations to counteract that shift in buoyancy. This is possible to accomplish, but at what cost? It might be simpler and better just to consider another fin. One that is less negative. Perhaps simply made of another material in the same style you like.
The same holds true if your feet tend to float. A more negatively buoyant fin may be the best solution rather than adding ankle weights or making some other compensation. Make sure if you do adjust for floating feet, that you do not go too far the other direction causing you to have to fight negative buoyancy in your feet now.
It is important to consider the kicking style and learn the correct one for the fin you use. This means it would be wise if you change fin style and that new fin requires a different technique that you request some time with an instructor comfortable in tutoring you in the finer points of this new technique. At least get good input on what those differences in technique are.
Split fins are very different from straight bladed fins. Other fins have very unique kick styles needed to optimize their performance. It is important to understand what your fins require. If you go on to use more than one style of fin, you will need to make sure you master each style’s required techniques and also create a ritual around each fins’ use to help you be able to seamlessly move from one to the other with minimal workup in between.
Just as we do not assume that breathing is something we know how to do as Precision Divers. We do not want to assume that we should “just know” how to optimize performance in any fin. I hear it all the time, “It is just fins.” Um, no it is not. Most divers that began with straight bladed fins who switch to split fins tend over kick them with far too great a length of kick. This only blows water through the split defeating the purpose of the design. Similar issues are faced by those making the switch the other way with under kicking. Other designs can be equally difficult.
Fins are the engines of our diving. So, make sure you understand how to get the best performance from your engine before you assume you “just know”. We generally do not jump into a car we have never driven without first “figuring out where everything is”. Make sure you do the same with your fins. If you get resistance from your instructor about a demand to work on use of fins, then find a new instructor. Same for a retailer. If the shop you use does not want to help you learn how to better use the gear they sold you, then it is likely time to find one that will. They should charge you for this service as well. You want to make sure that the service is provided fully and not blown off. Pay peanuts, you get monkeys.
Most shops would be surprised at the request, but more than happy to provide the education. I find that resistance to such requests is more a reflection on the possible lack of knowledge and/or understanding of the person you are talking with rather than a lack of necessity. Any major change in gear should automatically be followed up by time in a pool. More on this in a future post.
So, fins are the engines. With such a good engine on our feet, it means we should not need to use our hands to dive. If you are diver, this is the one thing, once you are aware, that will have you looking at divers very differently. You will begin to notice just how much even some highly experienced divers use their hands for all sorts of movements. Newer divers tend to use their hands a lot. Well, new divers that are not trained to not use them. But, the use of hands for controlling our diving is a crutch and should not be happening.
I am well known for asking people in my talks, “What are your hands used for in diving?” My answer is usually a less polite version of “for holding stuff”. Here is the problem if you rely on your hands in any form to control yourself while diving. The second you need to use your hands from something else; you just handcuffed your ability to dive. So, when you need to actually hold something, now you cannot dive as well as you did before having to hold something. Precision Diving is about being able to dive just as well either way, in fact all the time.
Let’s go back to our first post example of handing a diver a camera. Yes, there is the distraction factor. But, you very quickly realize that the diver with the camera had better be able to control their diving without the use of their hands. Because they just tied them up. It is easy to see. Those that have good skills and have learned to not use their hands make out better than those that have not, often in dramatic fashion.
This is true of dogmatic arm and hand positions as well. Most of which come about because the diver simply does not know what to do with their hands. So, they ritual a swimming position that locks them up. Well, this can work in the short term to have them looking better, but the same problem remains, when they need to perform in another way it throws the whole system into a tailspin. Performance suffers.
Try not to get locked into any one way of where your hands should be. In fact, get good at being able to dive the same way no matter where your hands are and in lots of places being used for lots of things. Just not used to control our diving in any way.
I will speak about the hands in front swimming style and other issues later in this post.
We have dialed in our fins and we are not using our hands. The next thing to do is make sure you understand swimming. Propulsion through the water is a lot of work. So, we want to make sure we do this as efficiently as possible with the choices in swimming we make.
I ask people all the time, “what is the most important part of swimming when we dive?” A lot of answers come flying back. My answer surprises most. The glide. Gliding is why we swim. Not the movement of swimming, but the motion we gain after we kick. You see a lot of divers just always finning. They clearly do not understand this concept.
The next time you dive, ask yourself, “Self, how much glide am I getting out of my kick?” The glide is the space between the notes on the sheet of music. It is to swimming what breathing is to all of diving.
This is why we need to talk about movement as a whole. Our glide is a function of swimming, but also a function of how much water we need to move out of our way as we swim and resistance as well. More of this is a sec.
As a diver, there are four finning styles we should know: Flutter, Modified Flutter, Frog Kick, and Modified Frog Kick. The modified version of each is simply a way to prevent the fin wash from going down to the bottom when you want to make that decision. Which is most of the time. Reach out to your instructor for help and if not them find one that is happy to help.
There are many other finning styles and it is fine to learn all of them. Just make sure you master these four first. Really, you want to get very good at each one before you add a new one to the mix even for these four. Until you are sure your kick is the best it can be it is going to be pretty difficult to figure out if other factors are affecting your ability to glide between your kicks.
Once you are feeling good with the kick, it is good to get some video footage of you doing it. Video analysis is the best tool to work on improving your performance. Also, it is much easier to see what you are doing and understand than trying to hear someone’s explanation of what they think you are doing. It is best to have both. With the advent of inexpensive high quality video systems, this is pretty easy to accomplish without needing someone dedicated to doing the video.
Now, kick and get moving. Once you get a few kicks in, see how long you can glide after each kick. Begin to play with how you kick and how often you kick. Which ways maximize your glide? This will change with your kit, your conditions, what the water is doing, and several other factors. Optimize and maximize your glide. The easiest and best place for this work is in a pool. The pool tends to minimize the impact of any factors outside of your performance.
Once you get good at moving forward, you can begin to work on flat turning. Flat turning is a fancy way to say turning using your fins to do so without any forward movement. If you get good at Modified Frog Kick first, then turning yourself with just the use of fins is easier. This helps provide that control that most feel they gain with the use of their hands. The fins will always do it better and more efficiently than your hands. Plus, you are more likely to have control of where the wash of that movement goes.
We work on flat turns because it is more difficult to do stationary. Once we get good at these, we can easily add slight movement in as we swim and glide to create turns. The layers of subtly grow as you get more refined in your control. Greater ability to control our diving is what gives us confidence. The faster that happens the more likely we will enjoy our diving more.
Eventually, you can learn to use your fins to move backwards. Yes, even with split fins. Moving backward is helpful when you are unable to turn around easily and often used by photographers when they are head down and looking under reefs or ledges.
All of this is connected with breathing and buoyancy. How and when we breathe and where our buoyancy is has profound impacts on our swimming. As Precision Divers, we use our control over all of this to optimize our performance. It is important we understand and have automated all our foundational skills so we can build to this level of integrating them together. If that integration is difficult for you, then go back to the individual foundational skills and work on them. The better the foundational skills are in basic applications the more likely it will be easy to use them in an integrated fashion. More in a future post on this topic.
If you begin to watch divers, which you will now, you will see that often swimming is used to compensate for other issues in the foundational skills. It is pretty common to see divers try to swim out of bad buoyancy. Swimming creates lift and that forward movement can have it appear to the diver that they are neutral because of the forward movement creating water flow over the divers body at a different speed above the diver than below. However, when the diver stops they immediately sink. Not to mention what the hard kicking does to their visibility and the environment, always fun for your fellow divers as well.
We know from the post on breathing that we can use our breathing control to compensate for this in the short term. Often, most divers try to swim out of it. Stop being that diver. If you feel you need to move to be neutral, do not swim more, fix the issue then swim.
Clearly, you are not going to get as much glide if you are swimming all the time because you are trying to fix the issue with your buoyancy. In fact, I doubt glide is any where near being on your mind at that point.
When we swim we should be able to stop at any point and not move at all. Well, unless we want to create that movement with our breathing control. Hopefully, with some forward glide at the end of the last kick. That is control and that should be our decision. Not a happy accident. So, make sure it is you making that happen at all times.
Other things like swimming backwards or backing out after looking under a ledge can be made easier by thinking about how we use our breathing as we do it. We know if we choose to cycle our lung volume near full our head tends to raise. So, if we cycle lung volume lower in the lung we can help to create a rise in our feet. Or perhaps our feet are already slightly elevated. Either way, we can use our breathing to help the backward movement out a bit. A bit of positive buoyancy controlled by our breathing as we create some backward movement is going to help our up and away movement. This reduces the amount of finning we need to do in order to create the desired backward movement. Also, it allows us to use less backward kicks to make the desired movement happen. This is a good use of lift to help desired movement.
Hands locked in front is being seen more and more these days. For most, it is just compensation from being uncomfortable with their hands and trying to lock them up so they will not use them. But, it also generates lift. For most, it is compensated for slight negative buoyancy. Subconsciously, this could have come about from feeling better about not losing control via positive buoyancy when they were newer or perhaps just a bad habit.
It is not necessarily a bad habit to have the hands locked in front, but you should be able to dive exactly the same with your hands in any other position as well. It creates the same problem as we discussed earlier in this post. What happens when you need to actually use your hands for something else, like holding something? If the answer is nothing happens, perfect. Then, this truly is a choice. If the answer is you do not dive as well, it needs to be fixed.
Use of lift in our swimming is a very important idea. As you progress, you are going to realize that you can use lift and buoyancy to move without swimming or to aid our swimming. You might even be told you move too fast and you respond with I was barely kicking at all. We can use negative lift on descents to literally fly on a down slope. Our fins then become rutters helping to change direction. If we want to flatten out we simply inhale a bit more, drop the tips of our fins a touch, and cycle our breathing there to stop the descent and exhale to restart it.
We can do the same on ascents, using our lung volumes and how we cycle our breathing to ascend without ever having to swim. This minimizes work and provides a great sense of control and confidence. All we have to do then is breathe and let bits of gas out of our BCD. Super easy to slow the ascent when it is our breathing and lung volume doing it. There are submarines that use changes in ballast and where it is held to move through the water without the use of propellers.
Refining finning skills and adding new tools to your performance toolkit is important. We also need to look at how trim and hydrodynamics impacts our movement as well.
Water is heavy. I will try to keep the math to a minimum. If we are moving through the water, we are moving water because we are forcing it to flow around us. Even small changes in how we make contact with that water can have real impact in the amount of work we need to do to move it.
Ideal positioning is how we optimize that. If we are not moving, then ideal positioning is not so important. If we are hanging out on a safety stop in blue water, it is not so important to be in any position. There is some research that shows some positions may benefit off gassing better than others, but there is still not much data either way. The point is; if we are not moving, how we move is not going to be in play at that time.
Ideal position is a flat position that minimizes the surface area that interacts with the water as we move. Generally, the torso is parallel to the bottom with a slight arch in your back. This helps you to see forward without having to crank your neck and/or not having to elevate your head, which would create more drag. Legs inline with the torso with a slight or more bend in the knee. This will depend on the kick you are selecting. This position is your default position when near or close to the bottom. It will be comfortable and easy once you get used to it.
One easy technique to help you “feel” it is to go to the bottom of the shallow end of the pool and be a bit negatively buoyant. You should feel the pool bottom from you knees to your shoulders for the most part with a slight arch to your back. Inhale and create some positive buoyancy and then drift back down and see if you can land in the same way feeling the same things. It is a good exercise to help you feel it. I find video really helps here. Project it on to a white board and draw your horizontal line inline with where you should be. If you match the line you are doing great. Assuming that is the goal at the time.
If you are going to put this much work into your positioning, you want to make sure you streamline your kit to match your work in streamlining you. So, watch your accessories. Clip them in tight to your body. If you are a fan of retractors, figure out how to use them without having them have what is attached to them dangle down. Consoles and SPGs should be brought in tight to the body and clipped up. No sense in having them create drag when they are not being looked at. Optimize your kit by routing hoses down and in. One small thing is not likely to make or break you, but lots of little things can add up to more than you think.
Water is heavy and having to move more of it requires more work. More work means more gas used and less time underwater. The goal is to minimize anything that is unnecessary work. Seawater is 64 pounds per cubic foot. For our metric friends, that is about a kilogram per liter. In theory, if I present one square foot of surface to the water and I swim one foot forward, I would need 64 pounds of thrust to make that happen. If I move the same foot with only somewhat poorer streamlining and present three square feet of surface to the water, I now have to provide 192 pounds of thrust to move a foot forward. For our metric friends, the numbers do not matter, the message is clear, bigger surface area, much more work.
So, small things like elbows sticking out, or a console and hose, or poor swimming technique that stops glide, or a combination of all or more can quickly add up to a lot more work. This means more gas consumed and less bottom time available. Several small improvements in streamlining will add up.
Drag also matters. Drag punishes speed. You need to move a lot of water out of your way as you swim. This takes work as we have seen. If you want to do that while going fast, it takes a lot more work.
where
FD is the force of drag, which is by definition the force component in the direction of the flow velocity,[1]
ρ is the mass density of the fluid, [2]
v is the velocity of the object relative to the fluid,
A is the reference area, and
CD is the drag coefficient — a dimensionless constant, e.g. 0.25 to 0.45 for a car.
Drag is calculated with velocity being squared. The important take home message is that the faster you go, the more you have to work in a function of how fast you go multiplied by itself.
I like to say with diving you need to slow down to speed up. If we move slower in the water, it requires less work. If you have good trim and streamlining, that is even less work. We want to give time for the heavy water to move past us. Ironically, when we move slower we get more glide, we get more out of our glide as it is more of our movement per kick. Also, it is likely that our technique is better when we are not rushing. Plus, our technique does not have to be as good when we more slower. Of course, we want to optimize our performance at all times, but there is a tipping point with work and speed where you will move faster and further by slowing down than if you try to go faster. You want to find that point and refine even more.
Technique matters. I have asked students to swim lane lines on the bottom of the pool and to get to the other end as fast as they can. They go screaming out and forget all technique, gas pumping through their lungs with a stream of bubble arching up behind them. I time the effort of course. When they are done, I ask, “What happened to your technique?” Oh yah. I then tell them to repeat the swim again, this time as fast as possible, but with the very best technique you can perform and maximizing glide. Which one do you think is faster?
The result is dramatic. Often, the results are 20 to 30% faster even though they feel they were going much slower the second time through. Thus, proving to them that slowing down actually speeds you up. Literally.
If you are not able to stop at any time in your diving and stay in the position you want to be in, then you want to work on these techniques. You can move weight higher or lower on your body to help, but it might be a better answer to look at potentially other choices in fins or other gear if the stuff you have is creating a problem that other kit will fix easily.
If you are diving dry, then learn to manage your bubble in your suit. Trim is much easier in a drysuit because your buoyancy is spread out over your whole body. But, you want to make sure you become intuitive with managing and breaking that bubble up into smaller pieces allowing you to feel in control of where your buoyancy is in the suit. Bubble management, if you will.
As you progress, you will refine your awareness and techniques. With this growth in your ability to dive well, you will work on subtler and subtler areas. Also, you will become much more sophisticated in the techniques you can use to control your diving and have a lot more tools to do the same thing in different ways. I will post about more subtle aspects in smaller posts in the future.
Be better this dive than the last one and better next dive than this one.
Precision Diving 