British commandos during WW2 - drowning enemy divers?

[Mr. Dooley]

Reading Deco for Divers, and stumbled upon quite a claim while learning about the history of nitrox mixes in diving. The author mentions the advantages of being able to dial in O2 content for rebreathers, and how a lower O2 mix would allow for deeper diving vs. a pure O2 rebreather - citing British commandos during WW2 specifically for using less rich breathing gas vs. their adversaries diving on pure oxygen. Then this doozy -

The British used this to their advantage and their simple but effective strategy was to simply pull their opponents to deeper depths until convulsions overwhelmed the enemy diver.

Is this... true? My (uneducated) instinct is that tales of actual submerged hand-to-hand combat were largely a thing of fiction.

 

[OTF]

Even if there WAS underwater hand-to-hand combat that seems like an unreliable, risky, and very difficult way to do it. Compared to say, using a weapon.

I could believe luring them deeper was a technique.

 

[Norwegian Cave Diver]

Met a guy (50 - 60 Years old) who said he was a navy diver on a submarine. On missions he would go into the torpedo tube, they would close the door and he would go do his mission and return the same way. Quite sure he was honest with me.

 

[JMBL]

Met a guy (50 - 60 Years old) who said he was a navy diver on a submarine. On missions he would go into the torpedo tube, they would close the door and he would go do his mission and return the same way. Quite sure he was honest with me.

That one is probably true. It was (is ?) a common practice among any combat diver in any navy, and is rather well documented.

As far as hand to hand combat under water, I might have an explanation : getting rid of an enemy diver can be done (according to the books I've read about military diving) by tearing of the mask and mouthpiece with a swing of the hand. Without the ability to see, nor to breath underwater the opponent is compelled to surface and isn't a problem underwater any longer.

 

[L13]

Met a guy (50 - 60 Years old) who said he was a navy diver on a submarine. On missions he would go into the torpedo tube, they would close the door and he would go do his mission and return the same way. Quite sure he was honest with me.

what navy?

In the US Navy, during the time that he might have served, divers assigned to submarines did not do torpedo tube swim outs for combat ops. Their purpose was submarine external maintenance and inspection.

It would have been Navy Seals doing the torpedo tube swim out.

 

[Norwegian Cave Diver]

Wasn’t a US guy

 

[Cthippo]

One of the SEALs wrote about doing that evolution on a French sub during an exchange program.

He was paired up with a French commando in the tube and was the second person into the tube. His partner was on his back facing up and the SEAL was looking downward so they were basically face to face in the tube. He said he was fine until they flooded the tube and then he got real claustriphobic real fast and when the outer door opened he rocketed over the top of the other diver to get out.

 

[happy-diver]

I am quite sure that every navy lost a few, considering that was the time of 02 toxicity experiments
and it was war after all

If you fill your lungs, breathe air before submerging, the 02 rebreather can take you deeper longer

 

[iain/hsm]

If you fill your lungs, breathe air before submerging, the 02 rebreather can take you deeper longer

Deeper yes, longer not so sure. It was a well known technique in the Royal Navy for a deeper 66 FSW dive using oxygen however the dive would be shorter not longer as the breathing bag did not have auto addition and on accent at the 30 FSW mark both the bag and lungs would be flushed out with pure oxygen and the bag then re adjusted with pure oxygen for neutral buoyancy as required. Risks were higher for blackout on your deeper longer suggestion due to the oxygen content being metabolically consumed leaving a lower PPo2 for the accent phase and with the problems associated with a static N2 volume level in the bag as internal volume decreased only due to the metabolic oxygen consumption of the remaining oxygen content within it.

The ideal dive in the period would be a tethered dive doing a warships hull keel depth inspection

The other lot introduced an auto addition tilt valve mechanism for the bag as it collapsed over time during a longer duration dive.

 

[iain/hsm]

British commandos during WW2 specifically for using less rich breathing gas vs. their adversaries diving on pure oxygen.

If your citing just WW2 the Royal Navy had a number of oxygen rebreathers from 1936 to 1943.
The only mixed gas rebreather after that I can think of was the Clearance Diver Breathing Apparatus built up in four options. A basic oxygen rebreather front mounted with a pendulum breathing tube to the standard Admiralty full face mask for shallow use. To which a back mounted small twin set was added with either a 60/40 nitrox mix or a 40/60 or a 32.5% option allowing diving to 180 FSW.
In addition the 1956 manual introduced the deep diving 300 FSW and the helium mixed gas to 500 FSW

Being that the Royal Navy mixed gas variants were semi closed the gas flow was selected for the four gas options by screwing in a small bronze frit into the regulator with the words OXY or MIX engraved at the end of the bolt. The frit was basically a brass bolt with a ruby mounted inside inside a fine sintered bronze filter tube fitted for micronic particulate filtration. The ruby was a real one machined by a watch company.