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Alcedo "Hydra" hydropneumatic gun

Thread Status: Hello , There was no answer in this thread for more than 60 days.
It can take a long time to get an up-to-date response or contact with relevant users.
Thanks very much for posting here. I read your description of the gun's construction and see that you are using the Zelinka (Zelinsky System) to provide the releasing valve operation via the inner barrel moving forwards from a stationary barrel plug, whereas in the Aquatech guns the plug moves and the inner barrel is fixed. The reason for the Aquatech being designed that way is that it is a variation on the Alcedo "Hydra", but with the pilot valve for the hydraulic locking chamber situated remotely via a small bore transfer tube of various lengths depending on where the trigger (and grip handle) is located. One advantage of the Aquatech "Black Sea" gun is the same biasing spring is used for the barrel plug of the releasing valve and the non-return valve on the hydropump, part number 27 on the schematic diagram.

I am hoping that you will create a new thread here describing your very impressive hydropumping gun and also welcome you to "Deeper Blue" where the "Pneumatic Gun World" is alive and well.

 
Hi Dima!
Thanks so, so much for joining here - so cool you are here!

Pete is an engineer like yourself and a bit of "history professor" for us all as I told you about. He is very good at putting technology in historical context, to compare one gun to other guns and other technologies and to explain how a certain gun works to the rest of us when we don't understand it

I agree, it would be great if you could find a bit of time to start a thread on the gun, so people can learn more about it in its own thread.

All my best and welcome again,
David
 
Here is an "Alcedo Hydra II" in absolute pristine condition, note all the grease inside it!
https://www.ebay.ie/itm/ALCEDO-HYDR...048148?hash=item1cb6264ed4:g:NN0AAOSwbF1Z9OSc

There is also an "Alcedo Hydra Sprint", but without its barrels. You received two barrels with each gun, a long barrel and a short barrel.
https://www.ebay.ie/itm/ALCEDO-HYDR...150819?hash=item4425a20363:g:jhEAAOSwBd1bSNyq

A more beat up "Alcedo Hydra Sprint" is for sale here, however it has its two barrels (that is I think it does , hard to tell from the photos).
https://www.ebay.ie/itm/ALCEDO-HYDR...370609?hash=item363a2ea9b1:g:jrEAAOSwC-JbSNmX
 
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I now have access to a "HYDRA SPRINT 62" and will soon start pulling it apart.

In the pursuit of high shooting power these large hydropneumatic spearguns threw away most of the other attributes that make a speargun a handy underwater weapon, in particular any ability to float after the shot as their heavy construction makes them absolute sinkers.
 
I have the Alcedo "Hydra Sprint 62" Manual which I hope to post here, but at 16 pages I will need to compress it.
 
The "HYDRA II" Manual is in Italian, but a rough English translation is attached as image files.
 
Alcedo "HYDRA SPRINT 62" Manual as pdf files, i.e. one file per page.
 

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And now the next eight pages.
 

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Still being relisted at US$2850 https://www.ebay.ie/itm/123531280272?ViewItem=&item=123531280272
The main attraction is everything is there (pressure gauge and air fill pump for the rear air pressure reservoir, often missing) and the gun is completely unused. Did someone buy it as an investment or did someone order it in the past and upon first picking it up thought “how in the (expletive deleted) am I going to swim around with this thing” and then put it in a storage cupboard for some relative to sell off many decades later via an eBay seller on consignment. Probably the same sentiments were expressed decades earlier by mail order purchasers of the equally heavyweight Hurricane "Carabine" dry spring gun which looked great, but weighs a ton! Spearfishing needs a handy gun, quick to traverse and easy to swim and dive down with, not an anchor like presence which taxes the arms. That said, some Tarzan physique type hunters dove into the depths with no wetsuit and only a dive knife to slug it out in the depths with some monsters equipped with these guns in the very distant past.
 
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The eBay seller is still trying to sell his virtually brand new Alcedo Hydra II, but 2500 euro (approx. AUD 4000) is a lot of money for a gun that will probably never see action as the rubber bladder in the bulbous rear tank has probably lost its mechanical properties as the rubber may have dried out and started to crack. You would only know when pressure hit it for the first time if it would hold. If it has been under pressure since being first sold then the rubber may have already started to break down where it is continually forced against the multi-ported honeycomb-like rear tank bulkhead plate.
https://www.ebay.com.au/itm/ALCEDO-...113601531317?_trksid=p2385738.m4383.l4275.c10

However the auction/buy-it-now photos show a spare bladder (the black sausage like object), but how it has been stored will determine if it is still good. Rubber will last a very long time if kept cool, in the dark (no UV) and out of contact with oxygen via a protective coating or wrapping in a gas impermeable membrane. That keeps the volatile rubber aromatic compounds in and oxygen and ozone out. Otherwise rubber parts are toast after several decades with maybe the exception of vehicle tires that are loaded up with anti-oxidants and protective rubber compound stabilizers.
 
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The innards of the Alcedo "Hydra Sprint 62" after initial dismantling. The rubber tube that acts as the moving bulkhead between compressed air and water has busted and torn and the gun lacks its forward barrels (long and short) and the corresponding spears.


Thanks to John Warren who took these photos and dismantled the gun using the comprehensive "Hydra Sprint 62" handbook.
 
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