SOS (Italy) Spearguns: the "Ringo"

[popgun pete]

The "Ringo" speargun was produced by "SOS" in Italy who also manufactured depth gauges and automatic decompression meters for scuba diving. The SOS decompression meter and the Helium depth gauge were two of their best known products. Scubapro distributed "SOS" products in the USA and through "Airdive" distributed them in Australia, but the main emphasis seems to have been on the scuba-related equipment rather than the "SOS" spearguns. I have never seen a "Ringo" except for a photo of one on eBay and another in the speargun collection of "Willy the Kidd" which used to be viewable on-line, it may still be, but I have since misplaced the URL. One of the "Ringo" guns had a trigger finger guard as part of the rear plastic grip handle and one had no such guard, it may have had a different handle moulding, but otherwise everything else about the two guns looked to be exactly the same.

The "Ringo" had a rear handle, which looked to be moulded in black plastic, that was situated behind the gun rather than under it, so like the current "Airbalete" the inner barrel lined up on the point where your hand gripped the handle rather than being some distance above it. Think of the handle as being something like that on an old style wood saw or panel saw. The tubular body forward of the rear handle was large and anodized in blue, then at about the mid-point the diameter of the body stepped down to a slightly smaller diameter which was anodized in black before terminating in a conical shaped muzzle incorporating the usual fore-sight or line wrap hook. There were also what looked like a few narrow longitudinal slots in the blue body section at either end, but I cannot be sure if they were slots or just some other feature. Beyond this description I know little about the gun except that it was allegedly a hydropneumatic type. Does anyone know anything more about this gun? I doubt that many found their way out of Italy as the "Ringo" appeared at about the time lightweight pneumatic spearguns with rear handles began to dominate the market, so anything that looked a bit odd and did not float after spear discharge was going to be struggling to make sales. I do not know for sure that the "Ringo" was a sinker, but I have never found a hydropneumatic speargun that floats without the spear unless it is enclosed in a bulky buoyancy jacket fitted as an owner modification.

I recall seeing another "SOS" speargun with a rear pistol grip type handle that from memory also had some longitudinal slots in the body tube, it was in the mid-seventies and looked like a grease gun with its all metal construction. It may have been a "hydro-elastic" gun as the salesman said it contained a rubber "vulcabomba", or something to that effect, but his description of the workings of the gun were very vague and he knew little about it except that it was for the surface shooting of flying fish! He said it was very weak when used underwater, but this was not stated as being from his own direct experience. Perhaps the Italian members of this forum may be able to enlighten the rest of us as these "SOS" guns have virtually disappeared without trace.

 

[popgun pete]

I just found the eBay auction photos from 2004 on an old computer, that first "Ringo" I spotted does have a trigger finger guard, it was obscured in the shadow of the black rear handle on the image, so both "Ringo" guns are exactly the same. A photo of the name sticker shows it as a "Ringo SOS Hydromatic". What I thought were slots in the blue rear half of the housing actually look to be slots on another sticker photo showing who sold the gun, i.e. the retailer's name. Maybe this "Ringo" gun is not a pneumatic speargun after all as there is no obvious air inlet valve location and the rear handle does not look like it is easily removed. The auction gun looked brand new, but had no spear, so whoever won it had no way of checking it out unless they picked up a spear somewhere else.

 

[popgun pete]

I finally relocated the "Willy the Kidd" pneumatic speargun page at http://www.apneateam.it/Fucili%20Storici/Fucili%20Storici%20-%20Willy%20the%20Kidd.htm where you can see the SOS "Ringo" speargun, along with many other less well known models. Those who have looked at the "Inalex Alpha C1" thread will also see the Technisub "Drago" there in a number of different barrel lengths. One thing that I should mention is the Mordem "Strale" is a hydropneumatic and not a carbon dioxide gun as indicated in his list at the bottom of the page. I know that for sure as the Mordem "Strale" was supplied with a hand operated air pump and like the Alcedo "Hydra" has a rubber bag pressure reservoir located inside the metal tank at the rear end of the gun.

 

[popgun pete]

Thanks to forum member caurro we now have the technical explanation for the "Ringo Hydromatic" speargun. The gun is not a pneumatic speargun, although superficially it looks like one. It is in fact a "hydro-elastic" gun. As with hydropneumatic spearguns, inserting the spear shaft into the inner barrel of the "Ringo" forces water inside the already flooded inner barrel into a variable volume storage area located elsewhere inside the gun. In a hydropneumatic speargun this injected water is placed under pressure by a compressed air reservoir that reduces in volume as water progressively replaces compressed air inside the gun, but in the "Ringo" the water is placed under pressure by the forceful act of radially expanding the resistive thick wall of a cylindrical sleeve made of "Vulkollan", a polyurethane material developed by Bayer. "Vulkollan" is their registered name for this product.

The "Vulkollan" sleeve is a cast object made specifically for use in the "Ringo" as it needs to seal at its front end and form a chamber with the inner barrel located co-axially at its centre. The longitudinal slots in the rear outer cover which surrounds the "Vulkollan" sleeve allow water on the outside to escape with the diametrical expansion of the sleeve during spear loading and to rush back when the sleeve collapses to its original size during the shot. The water flow in and out of the interior of the "Vulkollan" sleeve is controlled by a hydraulic locking chamber based trigger mechanism situated in the rear black plastic handle. A unique feature is that the hydraulic locking chamber's firing valve is not a piston type valve that plugs and unplugs the rear end of the inner barrel, in the "Ringo" it is a specially designed thick diaphragm made of rubber!

The great Italian Engineer Carlo Alinari designed the Alcedo "Hydra" hydraulic (hydropneumatic) gun in 1952, which first used the hydraulic locking chamber method in a speargun, so it is perhaps not a surprise that he also designed the SOS "Ringo" in 1967. Using a diaphragm means that the firing valve is both the inner barrel plug and the return spring given the flexible nature of rubber, the diaphragm just has to be thick enough not be extruded down the inner barrel when the gun is cocked and a large pressure differential exists between the inner barrel (at ambient) and the contents of the expanded "Vulkollan" sleeve. As with the "Hydra" pulling the trigger operates a pilot valve (or trigger valve) that opens up the hydraulic locking chamber to ambient water pressure. In the "Ringo" this locking chamber is termed the auxiliary chamber and in side profile is crescent shaped so that the central portion of the diaphragm can be flexed back to lay against the concave rear face of the auxiliary chamber. That rapid rearward movement of the unbalanced diaphragm uncovers the rear entrance to the inner barrel allowing all the stored up water under pressure inside the gun to rush down the inner barrel and push the spear rapidly out of the gun.

The front part of the "Ringo" contains foam floatation inside an outer barrel covering the length of the inner barrel forward of the "Vulkollan" sleeve housing. The "Ringo" was supplied in three different gun lengths, but all guns shared the same vented outer housing and rear pistol grip handle. The gun could be loaded while using air inside the interior of the gun, but produced a weaker shot than if it was water-filled and seems to be an option for firing the gun out of the water. It was claimed that the "Ringo" was as powerful as or even more powerful than a pneumatic speargun, especially as it could be pumped up using multiple spear insertion strokes. Although this increases the force of the subsequent shot, it also means the gun ejects a greater volume of water while doing so.

The "Ringo" is a gun of surprisingly few parts, but durability will depend on the service life of the "Vulkollan" sleeve, the rubber diaphragm and the seal of the pilot or trigger valve. The spear tail also carries a special seal which would require replacement at some time. Unique parts that are no longer available have seen many interesting spearguns retired when the manufacturer ceases production as there are no easy ways to replace these parts. This often deters buyers from purchasing the guns in the first place.

 

[Don Paul]

Cool gun Peter, great post.:friday

Cheers, Don

 

[popgun pete]

I am attaching photos of a disassembled "Hydra" to show the firing valve (releasing valve) referred to in my previous post. It is the pointy nosed cylinder immediately behind the breakaway tip body. Lined up behind it is the biasing spring and behind that is the trigger valve. They both insert in the front of the central handgrip as a single unit, the trigger valve slides inside the hollow rear end of the firing valve. This is a compact and simple arrangement, but in the "Ringo" the firing valve, firing valve seal and biasing spring are one single element; a thick rubber diaphragm with a pointy nose on the side that plugs the rear mouth of the inner barrel and a small leak path hole to allow pressurized water to get behind it in what is the auxiliary chamber.

Another attachment (see next post) shows a schematic and parts list for the "Ringo" with a brief explanation of the gun's structural assembly.

 

[popgun pete]

The "Ringo Hydromatic" speargun is claimed to be more powerful than equivalent spring and pneumatic powered spearguns by virtue of some comparative graphs of stored energy for each gun type shown in the handbook for the gun. The graphs, essentially simple sketches, show internal pressure versus barrel travel distance for each gun type, the area under the plot lines on these graphs represents the energy stored or work done in loading each gun. However what they do not show is the energy coming out when each gun is fired. Besides the energy stored in the "Vulkollan" sleeve another factor is how fast the expanded sleeve returns to its original shape as this will determine the velocity of the water and therefore the spear being ejected out of the gun. There are a range of polyurethane types with varying physical properties, but it is often used in thick cylindrical section isolation bushes in vehicle suspension systems to absorb and dampen road shocks and vibration. That is an energy absorption and dissipation role, not an energy storage role. In a speargun you want an energy storage system that maximizes the energy to be returned to the spear shaft as kinetic energy, so you want to lose as little energy as possible. This raises the question of how efficiently the "Vulkollan" sleeve worked as a spring, its power advantage may not be reflected by the effort required to load it. I am sure that a lot of effort went into finding an appropriate sleeve material, but just how effective it was requires input from someone who has actually used a "Ringo". Unfortunately the passage of time has crumbled the "Vulkollan" sleeve in the gun inspected by caurro, a fate that may have befallen all surviving examples.

 

[Don Paul]

Thanks for the Hydra images, if I ever have to take mine apart I have a better
idea of the components.

Cheers, Don

 

[popgun pete]

Adding a pdf file for the "Ringo" parts layout, smaller file, part numbers on diagram still readable even though resolution was not great on original document.

 

[Don Paul]

Pete, slightly of topic but many Hydras have you seen over the years.
I have a red one close to mint but the hardly come up for sale on E-bay.
Perhaps they are more common in their home land of Italy?
Here is a quick shot of mine.

Cheers, Don

 

[popgun pete]

Only this one, but I know of two others, really a gun for scuba divers to lug around underwater. Hardly a gun to sight along from the rear end due to the bulk of the centre section and the hydropump directly above it. Too heavy as basically the gun is full of water bar the rubber bulb in the rear tank which contains the compressed air. There must have been a competition to build the heaviest speargun ever and the "Hydra" won (back in the sixties).

 

[Don Paul]

Thank you Pete, I hadn't seen those two images. Mine will not get wet in my life time, but a love the style. But could it be heavier in the water than a long
Spring gun?

Cheers, Don

 

[popgun pete]

Yes, spring guns can be very heavy thanks to the long coil springs, sometimes they have two, one inside the other, but the guns are generally not bulky, rather they are long and slim. Exceptions would be the twin spear models where everything is duplicated, like the "Mepps", and the lever loaded guns like the "Sagittaire". Dry barrel spring guns are bulky due to the barrel tube and grip being expanded in interior volume to provide buoyancy as an offset to their weight in water, but they will be heavy guns out of the water, or when they do flood.

The "Ringo" is an attempt at making a highly simplified rear handle "Hydra", but doing away with the air pressure reservoir and some of the bulk. Use of plastic helps reduce weight, although the rear cover looks to be a heavy item even with the slots.

 

[popgun pete]

Some more information on the "Ringo" series of spearguns. The inner barrel diameter was 6.5 mm, which is very small. The longest "normale" version was about a metre long and had a working course for the spear of 85 cm. There are two shorter models, the "corta" (which is the gun shown in the above photos) and a pistol sized "cortissima". The difference between models is in the length of the black forward barrel section which contains foam elements surrounding the inner barrel, the "normale" forward barrel is about twice the length of the one on the "corta" and the "cortissima" has virtually no forward barrel at all, just a short projection to the plastic muzzle. Barrel assemblies were available as accessories to covert "normale" guns to the two shorter models, as were spears including durallium versions for above water use. An inox stainless steel shaft was available for the "normale" gun to replace the standard steel shaft. The rear pistol grip and "Vulkollan" sleeve housing was identical in all models, hence with multiple spear insertions they all contained the same volume of water at maximum radial stretch of the "Vulkollan" sleeve. The "normale" gun's spear could be pumped twice, the "corta" three times and the "cortissima" six times according to the instructions. There are some small breather holes located approximately 10 cm. from the mouth of the inner barrel, so the gun can suck in extra water without pulling the spear completely out of the inner barrel (shown on the layout diagram if you look closely at the pdf attachment). That would give the same hydrostatic pressure inside all guns regardless of their length, but of course the spear was propelled for shorter distances inside the barrel of the smaller guns and the extra volume of water above that required to clear the spear from the barrel did nothing once the spear was gone. Higher internal pressure achieved by spear pumping was essentially increasing the circumferential stretch of the wall of the polyurethane sleeve, rather like pulling a rubber band progressively further back on a band gun. The releasing valve hydraulic trigger mechanism makes this possible as until you pull the trigger it works like a one-way valve, letting water in, but not out. Aquatech "Dnepr" and "Black Sea" speargun trigger mechanisms operate the same way, only there the hydraulic valve is a piston and not a rubber diaphragm.

The diameter of the black forward outer barrel tube was 44 mm and the diameter of the blue outer cover with four slots at either end was 60 mm, so the guns were not slim by any means. At 6.5 mm inner barrel diameter, half that of contemporary pneumatic guns with 13 mm inner barrels, the "Ringo" fired a very slim shaft which in the era of 8 mm and 9 mm shafts probably seemed barely adequate. I suspect that aspect limited their appeal, plus to achieve maximum hydrostatic pressure the final push effort on the shaft was 75 kg, probably enough to bend it if it was not deeply inserted into the gun by that stage.

The guns were guaranteed for 5 years which was cited as a first for spearguns and with few components could be quickly disassembled. I wonder what the service life of the "Vulkollan" sleeve was, maybe the guarantee period is a clue.

 

[popgun pete]

Well it looks like the measurement of the inner barrel diameter was incorrect, so the 6.5 mm inner barrel diameter indicated on the dismantled "Ringo" corta photo above is wrong. I hope to discover the correct number as it is a significant determinant of hydraulic speargun performance. Another piece of new information is that the black outer barrel at the front is hard plastic, not anodized aluminium. The OD of the inner barrel is 18 mm, so that is where most of the strength is to resist bending of the gun body.

 

[Don Paul]

Great research Pete, I hope to see one in the flesh someday.

Cheers, Don

 

[popgun pete]

Latest information is that the inner barrel diameter of the "Ringo" was 11 mm, not 6.5 mm. That is large for a hydraulic speargun as the spear carries the sealing element of that OD, or very slightly larger, on its tail. In this case the sealing element was a specially moulded "Vulkollan" sleeve which also functioned as the line slide's tail stop. That revised inner barrel diameter changes a number of things as the spear diameter will now probably be 8 mm or 9 mm, that gives around a millimetre clearance on each side of the shaft when loaded into the gun. The shaft is probably centralized in the inner barrel by the small cone on the rear of the line slide fitting into the flared end of the muzzle opening. This small cone would also fit into the front edge of the sealing element, you can see this on the layout diagram if you zoom the image. The layout is a pdf file, so is safe to open.

 

[popgun pete]

The "Ringo Hydromatic" speargun is claimed to be more powerful than equivalent spring and pneumatic powered spearguns by virtue of some comparative graphs of stored energy for each gun type shown in the handbook for the gun. The graphs, essentially simple sketches, show internal pressure versus barrel travel distance for each gun type, the area under the plot lines on these graphs represents the energy stored or work done in loading each gun. However what they do not show is the energy coming out when each gun is fired. Besides the energy stored in the "Vulkollan" sleeve another factor is how fast the expanded sleeve returns to its original shape as this will determine the velocity of the water and therefore the spear being ejected out of the gun. There are a range of polyurethane types with varying physical properties, but it is often used in thick cylindrical section isolation bushes in vehicle suspension systems to absorb and dampen road shocks and vibration. That is an energy absorption and dissipation role, not an energy storage role. In a speargun you want an energy storage system that maximizes the energy to be returned to the spear shaft as kinetic energy, so you want to lose as little energy as possible. This raises the question of how efficiently the "Vulkollan" sleeve worked as a spring, its power advantage may not be reflected by the effort required to load it. I am sure that a lot of effort went into finding an appropriate sleeve material, but just how effective it was requires input from someone who has actually used a "Ringo". Unfortunately the passage of time has crumbled the "Vulkollan" sleeve in the gun inspected by caurro, a fate that may have befallen all surviving examples.

Here are the graphs mentioned in the post. They are for spring (molla), pneumatic (aria) and "Vulkollan" energy storage spearguns. Note that the graph for the "Vulkollan" speargun has a working course for the spear of 85 cm, so that will be the graph for the longer "normale" model of the "Ringo". What is not obvious is that this graph will for the second push of the spear, as to reach that peak of 75 kg the "Vulkollan" sleeve will be expanded hard up against the slotted alloy tube cover surrounding it on the gun. That means the energy for the first spear push will only be throwing water out after the spear tail has cleared the muzzle. So while not exactly cheating, the effort to load the "Ringo" to gain what looks to be an impressive performance is being understated here. The actual graph for the "Ringo" is estimated in the next diagram where it will require 2 spear insertion strokes to charge the gun for shooting, otherwise you will shoot with the energy indicated in the first part of the graph. This will explain why some reports I heard that the "Ringo" gun was weak are probably due to the spear being inserted only once. Sometimes it pays to read the instruction book or you will miss out on getting the most from your gun!

 

[popgun pete]

Here are all three sizes of the SOS "Ringo", the barrels can be swapped in the rear section in order to create different length guns with spears to match.

Note the water flow slots in the metal tank that holds the "Vulkollan" bladder and which allow the bladder to expand and contract during loading and shooting respectively without causing a hydraulic lock condition. The foam filling inside the black forward barrels helps decrease the weight of the front end of the longer guns by providing some off-setting buoyancy, but the "Ringo" will be a sinker.

 

[popgun pete]

The "Ringo" cocked to shoot with the "Vulkollan" bladder or lung filled with water injected into the gun by pumping the inner barrel with the spear which has a tail seal that acts as a one-way valve. The elasticity of the "Vulkollan" acts as a spring which stores the energy of muzzle loading and as it contracts to return to its original shape it squeezes the water back out via the inner barrel thereby pushing the spear from the gun. The alloy slotted "tank" tube confines the stretched "Vulkollan" so that it can only expand so far radially and the "tank" wall slots allow water outside the "lung" to escape as it is pushed from the "tank" during loading and to flow back again during the shot. Hence the description of the "Vulkollan" bladder as a "lung"!

I had thought the name was "Hydromatic", but the gun sticker shows "Hydramatic" which must be the correct name.