SOS deco meter

[regulator bj]

Previously posted in the computer section so maybe it just gets into this section. Any information on the unit will be welcome.

 

[Wookie]

It's nickname is a bend-o-matic.

 

[JKPAO]

^Yes it was!^
See you topside!

 

[Rich Keller]

This thing worked with a membrane that absorbed nitrogen at the same rate your body dose. The indicator along the top would show how much nitrogen was in your system. It would show what stops needed to be made by how far the indicator moved to the right. You would go to the first stop and wait for the indicator to drop then go up to the next stop. The upside was it operated without batteries.

 

[Akimbo]

This image is of the first Italian SOS analog decompression computer I know of. It was first marketed in the US by Healthways in the early 1960s, and later by Scubapro until the early 1980s. I believe your more compact model came out later.

The original was in a black plastic case and reinstalled in this stainless “can”. I used it for more than 20 years. As richkeller described, it is nothing more than a bag attached to a Bourdon tube pressure gauge (several of us took one apart).



There is a ceramic plug between the bag and Bourdon tube inlet with a gas permeability rate that approximated European decompression tables of the day. We “understood” the bag was filled with Nitrogen. Here is a catalog sheet:



Because the performance was a little less conservative than US Navy air tables of the day, we were constantly comparing it to tables for a reality check. To be honest, I personally never knew of anyone to get bent using one of these correctly (not pushing the limits). It is much easier to cut decompression short using an analog meter with a big fat pointer than on a go/no-go digital display… especially when you are chilled to the bone at a decompression stop.

Everyone called them Bend-o-Matics, but it was probably more from insecurity and bravado than fact.

 

[DA Aquamaster]

You can think of it as a mechanical decompression "computer" using a single compartment model rather than the 8, 12, 16 compartment models that are more commonly used in electronic dive computers.

The Scubapro version needed to be stored in its air tight case to ensure accuracy, and I can't recall anyone who had a great deal of confidence in them. The major advantage was the potential for multi-level diving, but to be honest, we were doing that already based on the idea that the average diver did not have enough gas in a steel 72 to get bent on the first single tank dive of the day at depths of about 90 ft or less.

So in a sense it offered very little over Navy Tables on square profile dives and offered only marginally more capability on multi-level dives. And at best you were relying on a single compartment decompression model that had obvious limitations.

 

[lothar]

Hi,
if you want to have a look inside the Decometer,
Dekometer demontiert

Lothar

 

[regulator bj]

Thanks for all the postings. Merry Christmas