Posts by Hardline

  • mammalian dive reflex short history

    Quote from Reefchief

    I dont think that article disagrees with those conclusions. it even says at the end.


    "If you still think the Aquatic ape theory is true because heart rate drops on face immersion in cold water. Dream on - Heart rate slows down because of the temperature change, not the water."


    Basically it seems to me to be saying that while there are very well known physiological responses triggered during freediving they have nothing to do with some innate diving ability given to us by aquatic ancestors and evolution, but instead extraneous factors such as colder temperatures, pressure, stress, lack of oxygen etc. I dont think it denies that things happen in our body as we dive that allow us to hold our breath longer, but more that these responses are your body trying not to die, rather than some romantic "dive response" or "aquaticity" evolved into us we haven't tapped till we go diving.



    You're missing the point. It's a physiological response that is well studied and documented. You can call it a reflex or response or that dive thingy...it doesn't matter. Everything your body does is geared towards it not trying to die.


    The Mammalian Diving Reflex

  • mammalian dive reflex short history

    That site about the reflex being a myth complete and utter BULLSHIT. There are NUMEROUS peer-reviewed papers on this very subject!


    Here's one of many!
    Mechanism of the human diving response


    It happens as soon as COLD water touches the face. The reflex is primarily triggered in COLD water. As soon as this happens, your heart rate slows down, the blood vessels in your extremities start constricting to send more blood to your vital organs and if you dive deep enough, your organs will allow plasma and water to pass into the thoracic cavity to keep pressure constant.


    When I worked in the ER. Some doctors that I worked with even tried it for treating SVT. It's a real thing folks.

  • Dry Breath holds, what are the benefits?

    Quote from hank

    Cardio (stationary bike) made the biggest difference in my approach to diving. It added 15-20 seconds to my average bottom time.


    I tried stationary breath hold tables at home but didn't notice any improvement.


    One thing for sure….it takes me a looooonnnngg time to warm up. I start doing my best dives after about an hour in the water. That could be 10 - 12 dives or so but when I start peeing a lot, my dive times go up. The first 8-10 dives of the day are rarely over a minute. Then I jump to 1 min 15-25 sec. Best days a bit more.


    I'm the same way. I always have better breath holds later in the day than first starting out. I've heard about the regular cardio working great for apnea so I started running again to test that theory out.

  • Dry Breath holds, what are the benefits?

    I have done breath holds on the elliptical because I feel like that mimics a similar leg movement to kicking underwater moreso than running or whatever but I dont feel like it helps or anything like that more than just getting out there, relaxing and diving. I believe your breathhold ability can change from day to day just like some days other physical activities feel better than others.

  • Shallow water hunting techniques

    Thats the hardest part of spearfishing...deciding which way to swim!!


    Also as far as shallow hunting goes...sometimes I feel like its better to hang around and work one area and other times I drift up and down the reef. Depends on what I'm seeing. I also tend to have better luck in the mornings and afternoons vs mid-day.

  • Understanding Your GoPro

    Understanding Your GoPro by Abe Kislevitz


    So you got a new GoPro HERO3 Black Edition! Luckily for you, GoPro has added about 137 different filming options so you’ll never really be sure if you’re using the right mode for the activity/film job. Hopefully I can break it down a bit and unshroud the mysteries of the modes. Keep in mind this is written for the slightly technologically inclined.


    A few things need to be explained when talking about the technical aspects of video resolutions, framerates, and video quality. In digital video there are a lot of different variables that go into what makes up the overall IQ (image quality). 1080P on a GoPro is FAR different than 1080P on an Alexa – and it’s not just the image sensor that makes it different. Processors in cameras are a huge determinant to how video gets from the sensor to the SD card. There are tricks and shortcuts that can be made to ensure the camera pumps out all the different modes we want in the end.


    Starting with the sensor, the camera is told to read a certain window of the overall sensor – the bigger the window, the more taxing it is on the processor. Reading the full sensor means you’re getting the full view coming from the wide angle lens of the GoPro. The sensor in the HERO3 Black edition is 12MP with a 4:3 aspect ratio. For 4K in the GoPro it’s reading the full width of the sensor, but not the full height – it’s capturing a 16:9 portion of the middle of the 4:3 full sensor. Since the final delivery is 4K, it doesn’t have to scale that initial capture at all. This capture window is identical for, say, 1080P Wide; however, it scales it down to 1080P for the final output. The final output size also has a say in processor taxation – we can get 4K at only 15FPS, while we can do that same capture window but scaled to 1080P at 60FPS.


    When we talk about digital video sometimes we use the term native to the camera or not. In the HERO3 Black the camera can capture that full wide 16:9 window, scale it to 1080P and do that natively 60 times a second. 1080-60 and 2.7K are just about the most optimal modes in the camera that really show the true power of the sensor and processor combo. There are some modes in the camera that are read off of the sensor slightly differently which will end up showing some aliasing (jagged edges). Take 1440 for example – look at 1440-30 at full resolution and compare it against 48. The way 48 is read and processed is slightly different than 30FPS to get that large of a resolution combined with a high frame rate. You’ll see the same type of thing in a Canon 7D when looking at 1080P at full resolution compared against 720-60 at full resolution. Canon’s 720P will have jagged edges because of the way they process the image to get a high frame rate from such a large sensor (high pixel count).



    Let’s talk about sensor window captures and fields of view (FOV). This is where the Medium & Narrow FOVs come from. 1080P Medium only captures a window in the very middle of the sensor, meaning we don’t see the full wide angle of the camera lens – only that middle slightly distorted part. The raw capture is still larger than 1080P, so it still scales down after the capture. 1080P Narrow is an even smaller capture window at the very very middle of the sensor so the distortion is even less. By this time, the capture size is nearly equivalent to the pixel size where we are reading nearly 1920 pixels by 1080 pixels (remember the full sensor is 4000 pixels wide by 3000 pixels tall). In this narrow mode it’ll appear fuzzier since the pixels are very small on the sensor and are accompanied by a decent amount of noise. When we are reading more pixels there are image processes that are done to clean up this noise – and scaling helps a lot. With no scaling, the narrow mode is extremely zoomed in from the original (imagine grabbing the middle 30% of a gopro photo – that’s what your full 1080P video will be). This is very different from digital zoom because the final readout is still native, we’re not digitally increasing the video capture size at all.



    Now that a few of these details have been explained very briefly, let’s take a look at all the modes below:



    Read More Here....

  • If your dive buddy doesn't surface

    Quote from Reefchief

    I think scuba equipment is a very good tool to have on the boat. Not just for emergency rescue situations but also for situations that are risky rescue situations waiting to happen (getting a fish out of a deep hole, unsticking an anchor or shaft at a depth at the limit of your capabilities) I have no misgivings about the lack of purity or sport in situations like that.


    But understanding of scuba physiology and safety as well as experience with equipment is very important to using it correctly. I would be extremely worried that a freediver in an emergency situation without scuba knowledge and practice could make a deadly mistake quite easily. Pulmonary Barotrauma caused by lung overexpansion is extremely easy to cause. All it takes is a deep breath at depth and holding it as you surface and your lungs literally explode.


    If you're rescuing a drowning unconscious victim using a SCUBA tank, they are most likely not going to be responsive enough to start breathing through a regulator. I would just focus on getting them to the surface instead of trying to deliver rescue breaths underwater and risking trauma to the lungs.


    After they are at the surface you can begin rescue breathing. Use immediate and aggressive measures. Start as soon as you surface, even in the water. Expect the person to vomit during rescue breathing.


    Once you are on a boat or back on shore (if shorediving) check for a pulse and begin compressions if absent. Continue CPR until rescue arrives. If victim recovers before rescue arrives, they still should be evaluated at a hospital because they can still suffer from respiratory problems after the fact.

  • If your dive buddy doesn't surface

    I pretty much agree with the throw anchor, call rescue and the jump in the water with a float system to begin searching for your buddy. Pulling your unconscious dive partner out of the water in 5 minutes vs 15 minutes (by the time rescue gets there) is a huge window in saving someones life.


    After locating the person, get them to the surface by any means. That could be diving down and grabbing them if shallow enough, shooting them with your gun if that's the only option or even bringing down a line when you jump in to dive down and tie the line to their leg or torso and then surface and pull them up to save strenuous work on your part to avoid becoming another victim.


    This also may be one scenario where carrying those "Spare-Air" bottles on your boat may come in handy.

  • Nate died spearfishing, Sunday 6/8/2014

    Judah, I know you cant see my texts but I still enjoy reading yours!


    I consider the Speardiver family my brothers in the ocean as well. I always try my damndest to look out for the guys I dive with and would hate that sinking feeling that comes over me when I cant find them for a few minutes. It's terrible to think about what happened specifically but any information that comes out of this may help prevent the death of another fellow diver.