Homemade Diving Apparatus




This is essentially a small diving bell that fits over the user's head and allows him to descend to moderate depths. It does not protect the user from pressure, but could be easily modified to do so. It should be noted that I am not responsible for any injuries sustained while using this device; If, however, you take the proper precautions, the possibility of this is small, even in the event of a pressure failure. This helmet can be made from simple, inexpensive materials. It can be operated by two people, and with some design modifications, could be made self - contained. I have made sustained dives of over two minutes without a problem, at depths of approximately ten feet.

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Step 1: Design

This apparatus consists of a watertight helmet which partially encloses the diver's head, and is connected to a topside air supply by a hose. It is chained or otherwise affixed to a ballast weight to counter the positive buoyancy of the air trapped inside the helmet. It is very similar to diving apparatus used in the early days of ocean exploration.

Step 2: Helmet Container

This is the main component of the apparatus. Any watertight container large enough to fit over your head should work; I found Sparklett's water bottles of the variety used in office water coolers to be particularly suitable. For those unfamiliar with these containers, they are large, clear plastic bottles about a foot and a half in diameter, and having a flat base, a mostly cylindrical shape, and a conical top terminating in a neck six inches high and two inches in diameter. I sawed the bottom off of one of these bottles to make my helmet. It is just large enough to fit over the diver's head, is transparent, negating the need to cut a window or porthole, and its neck provides a convenient attachment point for an air hose. A large plastic cement bucket would probably work too, but its lack of transparency would require the cutting of a viewing port, which would reduce the container's tolerance for pressure. You should pad the edges of the helmet to protect the diver's shoulders. I used two pieces of rubber hosing slit lengthwise and taped in place as pads.

Step 3: Air Hose

Many things would conceivably work here. I happened to use rubber aquarium hosing that I happened to have in a shed. This is about half an inch in diameter, and works fine. An old garden hose would probably be the most easily available thing. Just make sure you don't use drip irrigation hosing. It's riddled with little holes, and would leak A LOT. Other than that, just about any watertight hose would work. The way you attach it to the helmet and the pump will depend on the diameter of hosing you use, and the diameter of the helmet hose connection and bike pump nozzle. I'll leave that up to your ingenuity.

Step 4: Air Supply

In the first picture, you see a bicycle pump connected to the air hose to pressurize the helmet. If you use one, make sure it's a large one, capable of supplying enough air; an electric air compressor would probably work better and allow for longer dives. With my design, the diver must come up when the person working the pump gets tired. Probably, you could eliminate the topside air supply entirely and use a chemical re-oxygenation system inside the helmet itself, like on Isaac Peral - class submarines, and on the Columbiad projectile in Jules Verne's JOURNEY FROM THE EARTH TO THE MOON. If anyone knows how this could be done, feel free to comment!

Step 5: Ballast

You'll probably need about 25 pounds of ballast to get the helmet to sink. Old U.S. Army ammunition boxes filled with rocks work great, but failing that, use your ingenuity. Test to ensure that your buoyancy is right, and you can ascend and descend with ease. Ballast could be attached directly to the helmet itself, or hung on a chain or rope, as I did. 19th century divers used cast metal helmets, contributing some weight, and also wore weighted boots and large weights around their necks, one at the front, one at the back, contributing weight (see image). Anything heavy would work; I used rocks, but old metal junk, bricks, cast- iron pots, etc., would probably all work if you had enough of them. Make sure you have a rope tied to the ballast to allow you to haul it out of the water, or pull up the diver in an emergency.

Step 6: Operating

Drop the ballast into the water, holding it just under with the rope. Have the diver drop into the water and put on the helmet, taking care to keep it level. Let the rope out, and pump continuously to keep the helmet pressurized. When the helmet begins to descend, the diver will feel a sensation like a rapid descent in an airplane, and the diver's ears might pop. After that, pressure should remain constant. If the water level in the helmet begins to rise, air is escaping faster than the assistant topside is pumping it in. Some air must escape to stop carbon dioxide buildup, But not too much, or the helmet will flood. A system using pulls on the rope to signal distress is probably a good idea. Make sure to observe proper safety precautions.

Step 7: Closing Notes

Many modifications could be made to this design; the helmet could be sealed around the diver's neck or onto a dry suit to increase pressure protection and allow for greater depth, although it should be noted that this would make it more difficult for the diver to remove the helmet in the event of an emergency. The topside air supply, as stated earlier, could be eliminated and replaced with a self contained air refresher. You could mod it into an awesome steampunk helmet! The possibilities are endless! be careful, and have fun!

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    76 Discussions


    2 years ago

    Never EVER do this. As a diver I'm breathing air out of a scrubbed tank - this "bike pump" method uses air that is supplied by an oil coated plunger. The oil particles are in that air - though you won't see them - they will be present. Oil and your lungs are a good combo. Never do this!!


    3 years ago

    pretty cool, seen something like this on you tube


    9 years ago on Introduction

    i have got a air compressor,so what im going to do is make this but instead of a bike pump i will use the air compressor.

    9 replies
    Proana Dreistein

    Reply 4 years ago

    As others have said make sure your compressor either has a dryer to remove oil or even better doesn't use oil at all


    Reply 3 years ago

    oil-less is mandatory because of oxidation. At these low pressures the temperature is too low but scuba tanks have been filled with lethal mix (co - co2) from oil combustion in a compressor. Just filtering the oil out sets a bad habit.


    Reply 8 years ago on Introduction

    That should work fine, as long as the manufacturer of the compressor didn't use any strange, toxic lubricants, but that seems exceedingly unlikely.


    Reply 8 years ago on Introduction

    Builders, I am happy to see everyone interested in diving. I am a Salvage Diver by trade. Unfortunately, after reading this instructable I have identified some dangers. I DO NOT INTEND TO INSULT ANYONE...HOWEVER, I ALSO WANT YOU TO STAY ALIVE AND HEALTHY. I wrote everything, essentially, straight and to the point.

    Hypercapnia - excess breathing of carbon dioxide that commonly gets caught in "dead space" of helmet. Note the difference in the Mark V dive helmet and KM-37. Over time, engineers reduce the dead space to reduce this danger. I suggest designing a lower profile helmet.

    Asphyxia - simply put, lack of air to breath (in case compressor shuts off or leak in hose or what not)

    Carbon monoxide poisoning - By using a regular compressor and not a diver's are compressor, which specifically uses lubricants and has an intake far far from the exhaust, you increase your probability of death. Consider it like breathing air from the exhaust of a car...not good. I suggest researching proper lubricants and different diver air compressors. Also, learn more about High pressure vs Low pressure compressors.

    Decompression sickness - using the compressor will allow you to have more "bottom time." depending on depth and bottom time you may need to decompress, this allows nitrogen gases to be removed from your body. If you surface without decompression you may find yourself immobile. This is because a nitrogen bubble is trapped in the nerves that allow you to operate your legs, arms, or whatever it is that can't move. You then need to find a recompression chamber to shrink the bubble immediately. When treated hopefully the immobile body part will be able to move (expect loss of sensation). Aside from that, you can also die from Decompression sickness, depending if the bubble is trapped in your head or heart.

    Pulmonary Over Inflation Syndrome - Air can get trapped between the lungs and chest cavity. This is more painful than anything else, see a doctor. If you do not regulate the air from the compressor with respect to minimum manifold pressure you may also over inflate your lungs. Think of the cartoon breathing in a balloon and over inflating. This also happens when you go from a deeper depth to a shallower depth with too much air already in your lungs.

    Arterial Gas Embolism - Those going up and down 20 ft of water may find themselves within the cold grasp of AGE. Though different from Decompression Sickness it is treated the same as has many of the same dangers.

    I made this list as short as possible. If you research each danger you will find greater detail. I encourage everyone to take a class in diving to learn how ti mitigate the dangers. I wish you all safe diving and good luck.


    Reply 7 years ago on Introduction

    Hi, I am also a surface supplied air diver like xTOGx. I would like to confirm his warnings.

    I google'd home made diving bell and found this.

    I signed up just to confirm xTOGx and warn people that this is dangerous and not smart.
    You CANNOT simply use a regular air compressor to pump breathable air. You will get sick and possibly die. If you survive you will most likely never dive again. You will become too sick with respiratory issues, or you will become too scared to dive from a scary experience.

    If you want to experience this the RIGHT way, the way that is WORTH IT, then look up Kirby Morgan Helmets. Kirby Morgan makes industrial grade SSAir Diving Helmets. An even cheaper more recreational way are Bandmask surface supplied air masks.

    Developing surface supplied diving helmets for military and industry use took decade of research and many many lives of divers. Even if you dont kill yourself, you can mess yourself up for life and prevent yourself from ever being able to dive again!

    A guy who is certified to 1,000 foot depths.


    Reply 8 years ago on Introduction

    what kind of safety and/or danger(s) should one consider if he/she had an air pump for in and one for out and has thinking of shallow dives (10 feet or less) for a time longer than a single breath?



    Reply 8 years ago on Introduction

    Long time ago one seaman decided to dive using cast-iron kettle as a helmet and stones as a weight. When he reached the bottom he dropped stones and came to surface. He managed to cry 'help' and lost his consciousness. Soon he died.

    His mistake was that he held his breathe while surfacing. 3-5 feet and one breathe may be enought to seriously damage your lungs and die.


    Reply 7 years ago on Introduction

    Either one is not a good idea. Use Bellows. THe problem with pistons is that they tend to use oil as a lubricant. When it heats up under pressure...... it gets into the air. YOu ant to breathe that?


    Reply 8 years ago on Introduction

    Please don't do this. Unless it is for human use it can lead to mineral oils being absorbed through the lungs into the blood stream, damaging the lung lining and blood poisoning.


    5 years ago

    Cool system! I am attempting a small(ish) diving bell that works on basically the same principle! It is for shallow water though. Really shallow water...


    10 years ago on Introduction

    Another version is to use a 5 gallon bucket with a weighted collar. Bolt in a clear plastic viewing window with air hose entering from the bottom. CO2 will be forced out the open bottom.
     With ALL of these devices it is imperitive to adhere to these safety rules:
    Never use alone but under ACTIVE supervision.
    Never use any kind of compressor that uses oil AT ALL. This leads to suffication by coating the lungs preventing respiration. You cannot be saved once the lungs are coated.
    Stop immeadiately if your vision becomes cloudy. I have played with this type of activity during my preteens and luckily survived.

    2 replies

    I prefer to just use a transparent helmet, as cutting a hole in an opaque bucket not only limits your field of vision, but also creates the possibility of a seal failure.  As for oil, I don't think most bicycle pumps have any; it would work its way out of the system to quickly to do any good, and I'm sure something bad would happen if you got oil inside a bike tire.  This device is perfectly safe if used intelligently.

    Bike pumps usually have silicone grease made with petroleum products. Oil works fine in bike pumps if it is a type that doesn't deteriorate the seals or leather wipe (some use leather for seals).


    6 years ago on Step 7

    If you are over 18 welcome to the Darwin Club but handing this to a kid would be criminal. You can breathe hold dive 100 feet and when you surface the lungs have the same pressure and volume they started out with. Take a breath in that bucket just 5 feet underwater and surface without exhaling and the lung would be stretched 15% greater in volume. If the weights you duck-taped on to yourself fell off the buoyant helmet would shoot you to the surface you have a good chance of tearing lung tissue tissue. People dived somewhat safely with this style equipment for 200 years but there was a reason the equipement was metal, weighed 200 pounds, needed a team and cost more than a home.


    6 years ago on Introduction

    The change in pressure in 10 feet of water can cause an air embolism that will kill you DEAD - forget contaminated air - the gas in your blood expands blocks flow in the brain and that's it - lights out game over! This is not something to screw around with period - I strongly suggest this be taken down immediately before somebody kills themselves. This is beyond dangerous - as a Divemaster I'm begging you, don't try this.


    6 years ago on Introduction

    Just a +1 to all those warnings. This has the potential of being very-very
    dangerous and result to lung over-expansion (that's death) even in a
    deep pool or poisoning from contaminated air, depending on how it is

    If you like to explore the depths, try freediving or scuba diving and do
    not try this, please.

    I apologize for posting this to somebody's instructable, I know that they
    probably spent a lot of time and effort on making it, but this can be fatal
    in the wrong hands.


    6 years ago on Step 4

    You have to use ammonium nitrate or some such thing but it is toxic and will kill you when mixed with water