The Diving Helmet

Home
Flying
Science
Literati
Miscellanea
Curious Web Sites

This page last updated on 04/17/2017.

Copyright 2001-2017 by Russ Meyer


Growing up, I had a good pal named Rick.  In fact we've been friends since 5th grade.  I still visit him whenever I go back to my home town.  His family owned, lived in, and operated a motel called the Colonial Motel.  The motel had a pool where we whiled away many summer afternoons.

During the summer between 6th and 7th grades, Rick invited some friends and I over for an afternoon of swimming.  When we got to the pool, there was a strange contraption lying beside the pool in a heap.  It had a clear plastic bucket-looking thing connected to a small compressor with a coil of inch plastic tubing.  Rick said it was a diving helmet.  He turned the compressor on, donned the bucket-like helmet and jumped in the water.  I jumped in too and watched fascinated as he walked around on the bottom of the pool.  I took a turn with the thing and the experience was electric.  You could stand around underwater breathing normally with plenty of time to look around.  My entire underwater experience up to this point amounted to holding my breath while frantically trying to look around or do something.  It's hard to describe how different it was to be able to stand there as long as you like gawking at underwater wonders.  The diving helmet apparently belonged to one of the renters, because in a week it disappeared.  That experience was so cool and fun that I decided to try to build my own diving helmet.

I entered 7th grade and over the school year designed my own version of a diving helmet.  There were a lot of problems to solve.  First I needed a source of compressed air with enough volume to carry away exhaled CO2.  My Dad had piston compressor that was great at providing high pressure air but was marginal on volume.  The real killer though was oil vapor.  A regular piston compressor contains oil to lubricate the cylinder walls.  Some of that oil atomizes into a vapor and gets suspended in the air circulating through the compressor.  I really didn't relish the thought of breathing oil laced air.  Filters are available to remove oil from compressed air.  They are used to condition compressed air for use in paint guns.  I priced some of these filters and found they were way too expensive for my meager resources.  I toyed with building my own filter using a thick layer of cotton batting and a bed of charcoal in a large canister.  That just seemed like a huge hassle, and I looked around for easier alternatives.

My Mom had a canister vacuum cleaner with a detachable hose.  The hose could be connected to the outlet of the vacuum cleaner which provided a nice blast of air.  It certainly had the needed volume, but I wasn't sure how much pressure the blower could generate.  To test it, I took the vacuum into the bathroom, filled the bathtub, and held the hose underwater.  The blower forced air through the tube without the slightest strain.  Hey, this might work.  I took it out to the horse trough and jammed the hose all the way to the bottom.  The blower didn't slow down much and pumped gobs of air.  I wasn't sure how much pressure the thing could generate, but the horse trough was almost 3 feet deep.  If it could get air down that deep, then it meant I could stand in 8 feet of water as that would put my head at about 3 feet.  The vacuum-turned-blower looked like it would work well enough to allow a bit of diving in Rick's pool.

The next problem was that of the air hose.  I needed a length of tubing to connect the vacuum cleaner at the surface to the helmet underwater.  I didn't have the money to buy plastic tubing, so the project stalled again.  I puzzled and puzzled over this problem.  For a couple of weeks, I kept my eyes peeled for any discarded plastic tubing or something I could adapt to the task.  I was fooling around in our backyard one day when I stumbled over the garden hose.  Of course, the garden hose!  It was perfect.  I could get gobs of it, segments could be connected to get any length, it was water tight, it could withstand a good pressure, it had a large diameter enabling it to carry a big volume of air, and best of all it was free.  I made an adapter so I could couple the garden hose to the vacuum cleaner.

Now to the problem of fabricating the helmet itself.  I liberated a rectangular, 5 gallon, metal corn oil can from the dumpster behind my Junior High School.  I cut off one end and put it over my head; it fit perfectly!  For a faceplate, I located an 6x8 inch piece of 1/16th inch lexan and bolted it to the helmet.  I used a pipe nipple and nuts to make an adapter on the top of the helmet to attach the garden hose.  I attached a garden valve to the side of the helmet for use as an air vent.  I thought I might be able to regulate how much water the helmet displaced by fiddling with the valve.  This would allow me go up and down at will in mid-water.

One last problem remained to be solved.  The counterweight.  The helmet displaced 5 gallons of water.  Water weighs 8 pounds per gallon, so the helmet would try to float to the surface with 40 pounds of force.  That meant the helmet needed 40 pounds of counterweight for neutral buoyancy.  I got three large coffee cans and bolted them to the sides of the helmet.  I filled them with 25 pounds of lead shot borrowed from my Dad's shotgun shell reloading project.  I needed 40 pounds, so to make up the balance I topped the cans off with gravel.  I was only able to get about 32 pounds of counterweight into the cans.  The sheet metal helmet was on the verge of buckling with all that weight strapped on.  This obviously wasn't a very good long term solution, but it was good enough for a trial run.  Here's what the original version of the helmet looked like:

 

The whole contraption looked like this when it was all hooked together:

By this time, it was early summer and we had started swimming at Rick's pool again.  I hauled my diving helmet contraption to Rick's house and set it up.  I threw the helmet into the water and it sunk to the bottom.  I turned on the vacuum cleaner and was gratified to see that it could force air down as far as 10 to 12 feet.  The helmet filled with air and slowly rose to the surface.  I jumped in the pool and stuck my head into the helmet.  It worked!  I could look out of my little faceplate onto the aquatic world.  I only had one problem; I couldn't descend.  I just didn't have enough counterweight to keep the helmet submerged.  Well, I was much encouraged and was determined to solve the counterweight problem.  I dismantled the gizmo and took it home to ponder improvements.

When I got home, the first thing I did was remove the coffee cans bolted to the helmet.  The helmet was just not rigid enough to support the counterweights bolted to the side like that.  Instead, I drilled holes at each corner of the helmet and attached two baling wire loops.  These loops went under each arm.  To each loop I affixed a 20 pound bag of gravel.  Back at Rick's pool, I tried the new counterweight system.  It worked much better, and I was able to descend to the bottom of the pool.  The bags of gravel were too bulky though.  They were a real nuisance and I knew this wouldn't be a tolerable long term solution.  Back to the drawing board.  I lamented the thought of buying several bags of lead shot for counterweight.  I had few funds for something like that.  I toyed with the idea of custom forming some kind of concrete counterweights, or finding old discarded exercise weights.  My Dad finally came to the rescue by bringing home about 50 pounds of zinc plated steel formerly used as sprinkler counterweights.  They were exactly what I needed.  My method of suspending the counterweights using baling wire was not working either.  The wire really dug into the skin and was very uncomfortable.  I substituted cotton rope in place of the wire; much more comfortable.

Another trial at Rick's pool and I was sure I had found the magic combination.  The helmet worked beautifully.  You could walk on the bottom and come up to the surface any time you liked.  My friends and I had hours of fun with it that summer.  I found the adjustable air vent valve to be almost totally useless.  It made an effective and convenient air vent, but opening and closing the valve had little effect on the amount of air in the helmet.  It was not really effective for controlling buoyancy.

My all time underwater duration record was set that summer.  I was swimming with my friends, Tim, Bob, and Rick.  I went down in the helmet and sat on a lawn chair at the bottom of the pool.  It was fun to look around at my friends splashing on the surface.  After a while, they got out of the pool.  I sat there for a long time, just thinking.  Suddenly, my friends jumped in the pool again and splashed around for a while.  They dived down and looked at me through the faceplate.  Eventually, they got out again and I didn't see them for a long time.  Well, I had thought about all I could and was getting kind of bored.  I surfaced and looked around.  There was no one in sight.  I got out of the pool, hauled out the helmet, and turned off the vacuum cleaner.  It was very quiet and the afternoon shadows had grown long.  I went inside to find Rick and Tim watching TV; Bob had gone home long ago.  I asked them how long I had been down.  "Oh, probably four hours.  While you were down there, we went to K-mart, fooled around and came back."  Wow!  What a dive!  My hands and fingers were really, really wrinkly.

After using the helmet for a while, I became increasingly aware of the poor visibility the tiny faceplate afforded.  I made the faceplate the size it was because that was the largest piece of transparent plastic I could get my hands on.  It was kind of a bummer, because I could only look straight ahead and had to turn my whole body to look side-to-side.  I commented about this problem to my Dad, and later that summer he came to the rescue with a big sheet of 1/8th inch Plexiglass.  There was enough to form three large faceplates.  I removed the old Lexan faceplate, enlarged the original faceplate hole, cut two more faceplate holes on the sides, and bolted the new faceplates in place.  The new faceplates provided much better visibility.  You could turn your head and look all around.  It was also much easier to look up and down to see surface of the water and the bottom.  This was basically the last refinement I made the to helmet.  Here's a photo of the helmet in its final form:

The diving helmet in all its majestic glory.

 

Late in the summer I discovered an unnerving flaw in the design.  One time, Rick was using the helmet and was standing on the bottom of the pool.  Somehow the air hose got kinked; no air was making it down to the helmet.  Rick started thrashing around and trying to climb up the side of the pool.  He was really struggling.  I ran over and straightened the air hose.  Rick floated to the surface coughing and hacking.  He said the helmet had instantlyHey Rick, lets go diving! filled with water and he couldn't get himself extricated from it.  Suddenly, I realized what had happened.  With the air hose kinked, all the air remaining in the helmet immediately bubbled out the air vent.  Without the buoyancy of the helmet, there was suddenly 40 pounds of weight (the counterweights) resting on Rick's shoulders.  I could imagine this sudden onset of events causing a lot of confusion with the tangle of counterweight ropes and the huge weight dragging you down.  You could easily get panicky and start thrashing.  Hmmm...this was a real safety issue.  I decided to try it myself.  I got in and stood on the bottom of the pool.  Rick kinked the hose.  Gaaahhhh!  The helmet seemed to instantly fill with water and the sudden 40 pounds on my shoulders nearly knocked me over.  I flailed around trying to get out of the helmet.  It was easy to doff the helmet when it was floating weightlessly in the pool, but when it weighed 40 pounds it was very difficult.  I almost panicked, even though I knew what to expect.  Oh man, what a bummer.  I repeated that scenario several times, trying to find a way to remove the helmet while flooded.  I finally figured out that about the only way to do it was to bend at the waist with your face pointed straight down at the bottom.  You could then wiggle your arms free and push the helmet off your head.  This whole operation took about 10 seconds during which you had to stay focused and keep your cool.  I practiced this technique until I was at ease with the situation and could get out of the helmet without problem.

I began trying to think of a way to correct the flooding problem.  If the air flow was interrupted, the helmet needed to trap a bubble of air so the diver had something to breath and the helmet would continue to float.  The main problem was the placement of the air vent.  Up high on the helmet, it immediately vented any trapped air.  The vent would need to be moved to the bottom of the helmet.  Another problem was the air hose itself.  If the blower stopped for some reason, like a loss of power, the air could flow back up the hose and out the blower.  To prevent this back-flow, I would need to add a check valve to the hose.  The valve would only allow air to flow towards the helmet.  If air flow reversed, the valve would close trapping the air in the helmet.  The ideal placement for the check valve would be as near the helmet as possible.  With these modifications, the helmet would be much safer.  I never implemented them because they were a hassle and I had already found a way to get out of the helmet if it flooded.  If I made another one, I would probably incorporate those changes.

The next summer my family took a vacation to Priest Lake in Northern Idaho.  We stayed in a rented cabin at Hill's resort.  I took my diving helmet with me.  Our cabin overlooked the swimming area.  I set up my helmet and got in the water.  Wow, it was great!  I could see all kinds of things in the lake...sunken snags, cool rocks, deep drop-offs, etc.  I had brought a couple hundred feet of air hose, and was able to walk all over the place under water.  I could look up at my sisters floating on inner tubes.  I'd walk underneath them, do a little jump off the bottom, and grab their feet.  They didn't know I was down there and it would scare them to have a lake monster trying to pull them under.  Oh the screams!  Heh, heh, heh...so much fun!

After the lake trip, I began thinking what a hassle it was to transport the helmet and counter weights around.  All this stuff was heavy and took some time to set up.  In addition, my mobility underwater was limited because I had to walk on the bottom.  It would be much better if I could just swim around, but I couldn't do that with the helmet.  I started trying to think of another way to breathe underwater without using the restrictive helmet and all it's attendant heavy apparatus.

I imagined just anchoring the helmet to the bottom and swimming over to it for a breath when needed.  It would work like a little breathing station.  I could lift it up and drag it to another location while I was still underwater, and then from the new locale, continue free swimming with periodic trips back to the helmet for air.  I thought how awkward it would be to continually don and doff the helmet underwater just to get a breath.  Then I realized, I could just fasten a tube on the inside of the helmet and let it dangle out underneath.  I could use it like a snorkel to grab a breath.  Maybe I could just tether the helmet to my waist and pull it along behind me as I swam, all the while breathing through the "snorkel."  Thinking about it some more, I realized that the helmet was overkill for this.  I didn't need something that big that required so much counterweight.  Something the size of a coffee can would probably work just fine...it would be like a miniature helmet.  I could easily tether it to my waist and breath out of it with a short segment of tubing.  It would displace less than a gallon of water and would require only about 5 pounds of counterweight.  Well, this was a fabulous idea; I had to build it to try it out.  Here's what it looked like:

I built a prototype of this thing and tried it out in Rick's pool.  It had a lot of problems.  First, the excess air wouldn't vent very well resulting in a build-up of pressure inside the can.  After about 15 seconds of operation, the air would be forced out the mouth piece.  I just couldn't breathe with the air being constantly forced down my lungs.  The second problem was that when I took a big breath, I would suck most of the air out of the can.  This caused it to lose buoyancy and drop like a rock.  When I stopped breathing, it would fill with air and try to shoot back to the surface.  I messed around with it some, and I think I could of fixed these problems.  I just ran out of time and interest and never took it any further.  I'm pretty sure this approach would have worked eventually.

I really wanted to start diving deeper and I got to work improving the compressor.  One thing I thought of was using several vacuum cleaners connected in series, basically a multistage blower.  I think this would have worked, but it probably would have resulted in an increase of working depth of, at best, 10 feet.  I wanted to be able to go down 40 or 50 feet.  That would require a source of compressed air of 22 PSI with decent volume.  The only obvious solution was a cylinder of compressed air or a piston compressor.

I went back and looked at piston compressors again.  I thought of using an old worn out single cylinder lawn tractor engine.  Removing the cam shaft would permanently close the intake and exhaust valves.  I could then screw a plumbing "T" joint into the sparkplug hole and attach one way valves to either side of the "T."  When the piston went down, it would draw in ambient air through one valve, and when the piston came back up it would expel it out the other valve.  I could turn the engine over slowly and push a big volume of air through the air hose.  If I had enough torque, I should be able to generate a pretty good amount of pressure.  I could drive the pump using an electric motor or maybe with people-power via a bicycle  crank and chain.  I would still have to make an oil trap and put it in-line with the outlet.  The final problem was getting a couple of one-way valves capable of passing a large, low pressure volume of air.  I didn't know where to get something like that and besides I had no money anyway.  I eventually designed my own one-way valves using plumbing pipes of various diameters.  One version used a ball and gasket inside the valve and another version was based on flapper valves made from gasket material.  I constructed prototypes of both these valves and found the flapper version worked best.  The ball valve was a total flop because the air flowing around the ball inside the valve body would become turbulent.  This caused the ball to vibrate rapidly, severely restricting flow through the valve.  Unfortunately, I was running out of time and ambition to continue development of the contraption, and just shelved the whole thing.

One last development that I seriously considered was a large tank of compressed air.  I could take a counterweighted tank down with me.  The tank would be plumbed to the helmet and would be used to refresh the air in the helmet.  I could open the air valve to feed in a constant flow, or maybe conserve some air and just open the valve when I needed a fresh charge in the helmet.  I got an old Freon tank and cleaned it out.  I was ready to try it, but the opportunity never arose.

The diving helmet project was really fun, and could have been taken much further.  I remember it with fondness and occasionally consider setting it up and trying it again.  Maybe I will, if I ever own a house with a pool.