Refitting replica helmets for actual use?

[elmer fudd]

There was a thread here about 2 months ago on building a shallow water helmet, but one thing I've been curious about would be the feasibility of getting a replica MK5 and setting it up for actual diving, (just shallow water hookah type stuff).

It seems to me that if they were sealed up properly and pressurized inside that they could probably be made to work, or am I just speculating about something I have no clue about whatsoever?

Suppose you were to start with something like this
http://cgi.ebay.com/Morse-Navy-Dive...-V-Helmet-/130423595021?pt=LH_DefaultDomain_0

 

[sablefish]

i figure most replicas would not be pressure rated or properly sealed; they were more replicated for their unique look rather than their utility. They were replicated because the helmets were highly desirable as pub decorations and the genuine item goes for thousands of dollars nowadays.

maybe let your buddy try it first

 

[springs4me]

I've never seen a replica MK 5 have all the required pieces to operate the helmet properly and safely! Replica's are for display not use!

 

[Aceboyd]

It most certainly could be done, and without too much difficulty. Pressure rating is not an issue as the hat would not experience any pressure differential. The sealing IS an issue but easily overcome with silicone for the ports (make sure they are fastened securely please) and epoxy putty for anything else. You would have to add an inlet valve with the proper hose connection and weights to keep it on your head, all of which is explained in the aforementioned thread. That being said...it would be far from practical. The replicas that I have seen go from a very low $600 up to around 2 or 3 thousand! That could purchase a lot of good dive gear. And its a safe guess that corrosion would be a major issue as well. Yet if one had the time, money and inclination, it could certainly be accomplished.

 

[elmer fudd]

It most certainly could be done, and without too much difficulty. Pressure rating is not an issue as the hat would not experience any pressure differential. The sealing IS an issue but easily overcome with silicone for the ports (make sure they are fastened securely please) and epoxy putty for anything else. You would have to add an inlet valve with the proper hose connection and weights to keep it on your head, all of which is explained in the aforementioned thread. That being said...it would be far from practical. The replicas that I have seen go from a very low $600 up to around 2 or 3 thousand! That could purchase a lot of good dive gear. And its a safe guess that corrosion would be a major issue as well. Yet if one had the time, money and inclination, it could certainly be accomplished.

The $2 to 3 K price range would make it completely impractical. At that price I think I'd just get a genuine Russian or Chinese Helmet, or as you suggest, "a lot of good dive gear", probably the latter. That's just too much to spend on something that has very little inherent value.

I was thinking more along the lines of picking up a cheap helmet for $300 or so, sealing it up and then diving it using something along the lines of a modified hookah setup.

As I did more research into MK5's and their replicas however, what I found out was that virtually all of the replicas out there under $600 are exceptionally bad.

 

[Ben Dugger]

Reproduction hats don't have the air channels inside to conduct ths incoming air across the windows. That is the easiest way to tell the repros from the original. Also one must have a dependable check valve at the helmet. Stories of divers being squeezed up into the helmet from loss of air pressure are not too far fetched.

 

[DevonDiver]

Why would you want to do this??

Mythbusters - Surface Supplied Diver Death

 

[DA Aquamaster]

A couple of thoughts.

Divers getting squished into the helmets occurred in one of two ways:

1. The diver fell off the stage and fell into deep water far faster than the compressor could supply air to fill the suit. The resulting decrease in volume in the suit and helmet then caused the suit (and it's squishy pink contents) to squeeze up into the fixed volume of the helmet.

2. The surface supply hose broke/got cut and the check valve failed in the helmet, allowing gas to escape, creating the same loss of volume inside the suit and forcing things up into the helmet. Less extreme pressure differential as number 1 but still potentially dangerous.

The other great ways to die in a hard hat were to have the suit flood, then fall over so that the air pocket was not where you needed it to be in order to breathe - or have a valve fail in the helmet so all the air leaked out while letting water leak in.

A neck dam is a really good idea if you want to dive a helmet. It prevents you from drowing if you fall over as it will help keep air in the helmet. This is essential if you dive the helmet with a wet suit rather than with an attached dry suit.

On the other hand, if you dive it with a wet suit and a neck dam, you don't have to worry about getting squished into the helmet. But, if the helmet floods you need to have a way of bailing out or you are gonna drown.

Most DIY/recreational shallow water diving helmets basically sit on your shoulders and allow you to remove them underwater in the event of a flood so you can bail out to a regular second stage and mask.

 

[Aceboyd]

The OP intended to use the replica as an open-bottomed hat, so neck dams and suit squeezes would not be an issue. I wish I knew how to post a link to the original thread that he refers to. Many of these issues were explained there.
Back in my commercial diving days, we would ALWAYS test the non-return valve before we put a hat online. You could blow through a properly functioning valve easily, but it would lock up quickly when negative pressure was applied.

 

[elmer fudd]

The OP intended to use the replica as an open-bottomed hat, so neck dams and suit squeezes would not be an issue. I wish I knew how to post a link to the original thread that he refers to. Many of these issues were explained there.
Back in my commercial diving days, we would ALWAYS test the non-return valve before we put a hat online. You could blow through a properly functioning valve easily, but it would lock up quickly when negative pressure was applied.

That was basically the intention. I was thinking that if I could get a replica helmet for $300 or so, seal it up with fiberglass or epoxy or whatever and then run it off a couple of tanks on the surface that it might be something fun to do in the summer. Just for shallow water depths of 30' or less for S & G's. Having it look like a real MK V setup would make it that much more appealing.

Looking into it however, it seems like the decent replica helmets go for around $900 or more, and for me, that's just too much money to spend on something fun and goofy.

I'd still like to make a helmet sometime, as I enjoy monkeying around with strange gear as much as I like diving, but the price has to be reasonable.