REALLY stupid questions about hard hat diving

[tparrent]

I know I should know this but....

In days of yore when divers wore hard hats, canvas suits and big heavy boots how did they work?

I assume that the topside air had to be fed at increasing pressure as the diver's depth increased. It follows that deep divers had to make decompression stops. If that's the case, did they just hang on the end of a cable at each stop? Can't see how they would be neutrally bouyant at each stop. They must have been overweighted, right?

Why did they have to wear so much weight compared to, say, a drysuit diver? I can see that the boots would have to be heavy to keep them upright what with that big helmut but why so much wight on the belt?

Why the helmut anyway? If the suit was pressurized enough to prevent major squeeze, why did the helmut have to be hard instead of something soft but airfilled?

Can you tell I watched "Men of Honor" tonight?

 

[Gary D.]

I know I should know this but....

In days of yore when divers wore hard hats, canvas suits and big heavy boots how did they work?

I assume that the topside air had to be fed at increasing pressure as the diver's depth increased. It follows that deep divers had to make decompression stops. If that's the case, did they just hang on the end of a cable at each stop? Can't see how they would be neutrally bouyant at each stop. They must have been overweighted, right?

Why did they have to wear so much weight compared to, say, a drysuit diver? I can see that the boots would have to be heavy to keep them upright what with that big helmut but why so much wight on the belt?

Why the helmut anyway? If the suit was pressurized enough to prevent major squeeze, why did the helmut have to be hard instead of something soft but airfilled?

Can you tell I watched "Men of Honor" tonight?

Lots of good questions.
Helmet 55-65#
Suit 18#
Boots 35# a pair
Weight belt 84#

They were/are for heavy work underwater and can be used in much heavier currents than SCUBA.

They work great and are very comfortable once you’re in the water. You can make yourself heavy or get so buoyant that you can shoot to the surface like a rocket.

The diver has control of both his air supply and exhaust rate.

All the problems that SCUBA divers deal with are the same a Hard Hat diver deals with. The suit is not pressurized and is just a big thick heavy-duty drysuit.

You can get upside down but it’s hard and very dangerous.

They are about the most comfortable and enjoyable rig ever outside of scuba.

The suit in the courtroom was a HEo2 unit. About 100# heavier than the air rig.

Gary D.

 

[ScubaSixString]

I know I should know this but....

In days of yore when divers wore hard hats, canvas suits and big heavy boots how did they work?

I assume that the topside air had to be fed at increasing pressure as the diver's depth increased. It follows that deep divers had to make decompression stops. If that's the case, did they just hang on the end of a cable at each stop? Can't see how they would be neutrally bouyant at each stop. They must have been overweighted, right?

Notice they aren't wearing fins, or a BC. Thats because bouyancy isn't a concern, as long as it is negative. They were liffed in baskets and lowered that way. Deco was probably done dry, in an on ship reco chamber.

Why did they have to wear so much weight compared to, say, a drysuit diver? I can see that the boots would have to be heavy to keep them upright what with that big helmut but why so much wight on the belt?

I dont think the suit WAS pressurized. But if it was, there was no way for the diver to vent the gas.

Why the helmut anyway? If the suit was pressurized enough to prevent major squeeze, why did the helmut have to ee hard instead of something soft but airfilled?

A hard hat keeps the compressor from having to fight water pressure in order to give you gas you can breath. Also, a soft hat would probably have been difficult to make.

Can you tell I watched "Men of Honor" tonight?

But i don't know all that much about it.

 

[Gary D.]

Notice they aren't wearing fins, or a BC. Thats because bouyancy isn't a concern, as long as it is negative. They were liffed in baskets and lowered that way. Deco was probably done dry, in an on ship reco chamber.

I dont think the suit WAS pressurized. But if it was, there was no way for the diver to vent the gas.

A hard hat keeps the compressor from having to fight water pressure in order to give you gas you can breath. Also, a soft hat would probably have been difficult to make.

But i don't know all that much about it.

Buoyancy was a major concern. To heavy and it was hard to walk. To light it was almost impossible to walk. There needs to be a half way point for easy solid walking. It is also possible to swim in it. Not to good but doable.

Sometimes a platform is used to raise and lower divers and sometimes they free decend and free assend. Either way it is easy to do. The platform just has better control in calm water. In rough water it can be very dangerous to ride a platform.

The suit was not pressurized any more than needed to stay comfortable and adjust buoyancy. The diver DID have control over air venting.

It doesn't matter if the hat is hard or soft as far as the amount of air being pumped down. It would be almost impossible to work in a soft had. So much more weight would have to be added it would befeat the purpose. Like diving with Fiberglass SCUBA tanks.

If you ever get a chance to dive one do it.

Gary D.

 

[PaulChristenson]

If you want to experience it and are willing to travel...
http://www.divemasterscuba.com/club/trips/hardhat/hardhat.html

 

[SteveC]

Think about the pysics here. The helmet is connected to the suit. They are both pressurised. Just like a dry suit. And of course the compressure is fighting the pressure. The helmet is not like a submarine. The deeper the diver goes the more pressure is needed. I believe the diver has a mouth operated valve to control the pressure.

 

[spectrum]

I thought that pressure was controlled by an excess of flow. Any flow that would bring the suit above ambient pressure was ventet. If the pressure was more than ambient water bubbled out. Flow was intentionall kept above the need. A check valve prevented flooding from the vent if there was a lapse in the air supply.

Another check valve allowed ait to enter the suit but prevented the diver from getting pushed up throught the supply hose if the air flow stopped. Remember that if the supply line went dead it was a main line to 1ATM. The suit would het squeezed like a tube of toothpaste. The check valve held the suit at ambient pressure.

Pete

 

[tparrent]

Ok, some interesting responses, thanks. This leads me to ask about one of the horror stories often told.

The story goes: if a hard hat diver is at depth and his air hose is cut or the flow of air somehow interrupted, then the suit compresses so violently that his entire body is pushed into the helmet!

If the suit is not pressurized I don't see how this could happen unless it was accompanied by a fall into the deepest depths. I suppose that a uncontrolled descent without air would compress the suit but just losing the air would not, right?

Incidentally, this is not a situation I expect to encounter so I refuse to buy additional equipment to counter it

 

[tparrent]

Wait, that doesn't make any sense. If you are in a dry suit you experience squeeze only because the air in the suit compresses, right? If you were to cut yourself out of the suit, your BODY would not be compressed because it is made of uncompressible liquid, right?

Certainly if you descended far enough it could get pretty darn uncomfortable but freedivers go to 400 feet without getting squished into jello so it's not jsut depth that's the issue.

Are we talking submerged myth here?

 

[DA Aquamaster]

If you were diving in a surface supplied helmet and the compressor quit or a hose ruptured at the surface, the pressure in the closed suit would tend to want to push you into the helmet to equalize the pressure.

But if the helmet has a one way non-return valve from the surface, that is not going to happen.