Real vintage gear

[Creed]

You want vintage gear? Here's some vintage dive gear:
www.middelaldercentret.dk/projectindex.htm

[scubanut]

Not a chance in a million would you get me into that gear. I will stick with the more modern vintage gear anytime.

[Broxton Carol]

I wouldnt even use the rope those jokers used to pull that guy in and out with. Good luck!

[swimjim]

If they are real authentic, the helmet would not have a one way valve where the air enters the helmet as that was a fairly "recent" developement. If there is a sudden compressor failure at depth, that could really suck. And I do mean really.

Jim

[SeaRat]

Hopefully, they put that non-return valve in the helmet to ensure that the diver was safe using the vintage gear. Drowning is one thing, but being trapped by water pressure into the helmet is quite another. You can only go so far with the vintage stuff. By the way, one of the compressor operators having a heart attack is why the compressor would stop;-)

John

[Ron Hearn]

Folks, that is a open water helmet concept, if the air was suddenly lost because some guy received a spear in the head the helmet would simply fill up with water. if the divers helmet was fastened to a suit and used as some type of buoyancy device than yes, with out a check valve his body would be sucked up into the helmet. a super deviled ham effect.

Ron

[pearldiver]

I forgot the name of it, but I'll find out for ya. Now this is the story we heard.......There is a wreck in Lake Michigan, that when it sunk, there was an attempt to raise it. The first thing they tried was to fill it with ping pong balls. The attempt failed because of the suction from the hull of the ship stuck in the bottom. The second attempt was to send hard hat divers to the bottom, put slings under the hull and attach 55 gallon drums to the straps. This was done and the hard hat divers, wearing full dress outfits went down and began to fill the drums with air. The bow of the boat lifted and one of the divers tending to the filling of the drums saw the bow slowly begin to rise. It shifted position, and one of the straps slid off. The boat of course sunk again, right atop of another hard hat diver. To this day, you can see the hose and safety line going under the wreck along with the straps they used and a few 55 gallon drums laying off the side of the wreck in the sand. It's very eerie, and we kind of swim around the hose and line. But, if anyone wants a hard hat outfit.......

[SeaRat]

Ron,

That is true, that the helmet would likely just fill up, unless...it was seated fairly firmly on the divers shoulders. A look at the photo shows that it does fit fairly snugly around the shoulders. In the case of pumping not being fast enough, water would come up in the helmet fairly slowly. But in a case of catastrophic failure of the line at the surface, there would be a large amount of water pressure differential. Here's the calculation:

13 feet underwater at 0.445 psi per foot equals 5.785 psi at that depth.
If the helmet had an opening about 12 inches across, the area would be pi times the radius (6 inches) squared, times the psi at that depth, 5.785 psi.

5.785 psi x 6 inches squared times pi = 654.3 pounds of force suddenly against the bottom of the helmet.

That would probably be enough to seal the helmet at the shouldlers, and cause some awful damage to the diver. The one possibility is that the hose would collapse, in which case there would be no pressure differential. But again looking at the photo, the hose looks pretty substantial. That would indicate to me a potential problem. Bottom line, I would not get into that helmet without a good, functioning check valve at the helmet.

John

[Ron Hearn]

John

I've been helmet diving now for 26 years and have dove just about every type of contraption man has invented for for his head to dive with. I hardly beleave that back in those times the helmet or the cloth suit was capable of such suction effects. Now on the other hand I do have picture of a young MK v diver and his entire body shoved into his helmet because he fell off of his platform and increased his depth to another 56 feet below. The funniest thing is there are lots of helmet collectors in the US but very few actually use them, I am not one I use dive and play with every diving gaget I can get my hands on.

Ron

Ron

[SeaRat]

Ron,

I'll take your word for it; I've never been in a helmet at all. I still wouldn't put that helmet on though, without the check valve (maybe that's simply a phobia LOL). I was thinking that if there were no clothing (they were wearing what appeared to be either wool or leather), and the person was fat, there could be that kind of problem with a seal forming around the chest and back. Take a look at that helmet again, as it does fit closely to the diver. It would be akin to the diver in a pool who got his arm stuck in a drain line, as it formed a water-tight seal around the opening.

Just for everyone's information about the diver who fell that Ron described above, using the above assumptions and calculations, if that diver fell another 56 feet in salt water, it would be 2,818 pounds pushing him up into the helmet, with really awful results.

John

[Ron Hearn]

Hi John

Believe it or not there are newly "trained" inexperienced commercial divers out there graduating every day from well known schools, who insist on not cutting there long hair which is one big problem with helmet diving. It only takes one time to have your long hair caught up into a check or dump valve to bring them home to reality. In the early days of full dress helmet diving, the Greeks many times killed them selves by not having check valves built into the air intake line, but as time past and new advancement came about check valves became mainstream. I dive my MK v suit on a regular bases and the check valve is my number one priority. I think in the very early days of diving that air supply malfunctions killed more medieval divers than the lack of helmet valves as depth and getting back to the surface quickly was a major playing card for a diver out of air.

Ron

[jrvancealt]

in this good state of california i would have to get a parental consent form to touch one of those helmets with a ten foot pole

by the way if you explore the site a little longer you will find they do use a check valve such as a flap valve or something similar

[duckbill]

"5.785 psi x 6 inches squared times pi = 654.3 pounds of force suddenly against the bottom of the helmet. "

It seems to me....
the above calculation would be true (I haven't double-checked it) IF all the air could escape at once. Not included in the calculation is the resistance throught the smaller diameter hose, not to mention the drag on the airflow in 13 feet of it. Lets say there is a gap around the shoulders of the same area as the hose. The flow of water would be the same as the flow throught the hose. I really don't think all of the force would come through suddenly.

As a side-question, why didn't someone just design the air to bubble in at the bottom of the helmet, as into a diving bell? Then, should the airflow cease for whatever reason, the air would stay at ambient pressure in the helmet and the water would only be sucked up the hose. I'm sure there must be a reason. Just wondering.

[Buzz]

duckbill

To dispell what seems to be some confusion......
diving helmets 'are' designed to bubble at the top.
they all have their exhaust valve at the lowest possible point on the helmet.
that is not the point.
the problem is the air input line !!!....its not the airflow that counts......its the air pressure that keeps the diver from getting sucked up into the helmet.!!!!
if the air hose at the surface breaks, develops a hole, beccomes disconnected, etc., etc., .......the air in the hose and the helmet (if there is no valve or the valve fails) will go to atmospheric pressure.
however, the diver's body is at whatever water pressure which coincides with his current depth.
all that pressure is then applied to the divers body across the 12" opening at the bottom of the helmet.
this results in the diver being pushed up into the helmet......or.....the big squeeze .....as the old timers would call it.

Buzz

[duckbill]

No confusion here.
I understand the design concept of the old hard hats. I was questioning whether they could have been designed differently. The input, or supply, line was what I was referring to ("...air to bubble in..). I was just wondering why the air could not have been supplied by a controlled freeflow into the bottom of the hard hat. Kind of like bubbling air through a straw into the opening of an inverted glass. If you were to stop blowing throught the straw, the air in the glass would still remain at ambient pressure. Maybe that design would affect CO2 buildup somehow. Dunno.
The rest of my post assumed that the helmet in the web page (see the original post) was NOT sealed to the diver's suit ("Lets say there is a gap around the shoulders..."). I wasn't stating facts...just surmising. A situation where the helmet was sealed to the suit would be a whole different ball game!