Sea Hornet CO2 Speargun?

T.D Preece/Sea Hornet made these on Sydneys Northern Beaches. A thing of beauty they were, well made & beautifully chromed. It would be hard to find any in collections now as they are considered a prohibited weapon In Aust. The son of the owner sent all the remaining parts to landfill 20 years ago when the new firearms regs came in. Lots of good stories & photos of big cod & jewies (five at a time! yes they were that powerful!) still getting around & being shared.

Expellable gas spear propulsion is the key determinant as to whether the weapon is lawful or not in Australia as such spearguns are independent of the diver’s strength to load them. Non-consumptive (of gas) guns were also in for a hard time when being imported as people in Customs Inwards Processing (not necessarily Australian Customs employees!) could not tell the difference and operated on the principle "if in doubt then rule it out". Many battles were fought until someone at the top understood what the differencs were and then pneumatic spearguns were no longer considered to be "air rifles", which are of course consumptive of gas by blowing a small metal pellet out with expellable air.

I came back to this thread as I recently wrote something about how the Pelletier spearguns worked which were probably the simplest possible carbon dioxide spearguns as the gas tank at the rear was twisted on the gun body to open a check valve and gas then filled up behind the spear which was already locked in the gun. Thus the Pelletier and its modern equivalent the Maco2 don't actually have a gas metering system, they just use the tank valve and the rest of the gun is basically a long pipe with a grip handle and a single-piece trigger pivoting in the grip frame. These triggers pivot on one side of the gun body and have a bent arm which moves the part of the trigger that you pull against onto the gun's centreline and can be thought of as “outrigger triggers”.

The Sea Hornet “Sea Rocket” was in a different league as it had a gas metering system and a trigger operated valve. That meant besides pulling the trigger to shoot the spear the gun could also be used to deliver a blast of gas without a spear in the barrel. That came in handy as sometimes a big fish could be sent to the surface after being speared by giving it a shot of gas in the mouth or other body aperture to inflate its guts and send it up to the surface.

The “Sea Hornet” Rocket gun was designed by Michael Calluaud and was built for TD Preece Sea Hornet to market. There were other carbon dioxide guns which were also more complicated than Pelletiers, such as the “Super Tum”, but when the rules changed for spearguns to be allowed which were only manually loaded then the carbon dioxide speargun's days were numbered. Ironically in France the carbon dioxide gun was banned fairly early on, but the ban did not extend to the French colonies in the Pacific and that is where the carbon dioxide guns such as the Pelletiers were most often used against very large fish and sharks.

A little more information on why carbon dioxide is used as a gas in spearguns. For a speargun to be effective it needs to shoot consistently and that means the gas pressure for each shot needs to be exactly the same. Carbon dioxide gas is compressed to form a liquid and in the storage bottles as well as the liquid there is a certain amount of gas. The liquid transforms into a gas with absorbed heat and creates a pressure of around 900 psi in the container and if you release gas then more gas converts from the liquid. The pressure in the container will remain at 900 psi until the very last drop of liquid carbon dioxide is converted to gas after which the pressure will fall as gas is released. It is this constant gas pressure that makes carbon dioxide an ideal gas to power a speargun with.

Here is a Maco2 speargun, basically an updated Pelletier.

The cylindrical gas tank attaches on the handle butt where you can see the fitting with the knob which is the check valve that opens and closes to control gas moving into the gun. Hence unlike its forebear you do not have to twist the tank to do the same job.

I have been loaned the grip handle and working parts of a Sea Hornet "Sea Rocket" to try and figure out how the metering system for the gas operated. One thing I already know is the spear tail had a sealed tail of sorts which was also a line slide stop diameter made of some type of white plastic that used friction and a partial vacuum to hold the spear in the barrel. Hence unlike the "Pelletier" the gas blew the spear out of the gun once the trigger operated an internal valve.



This gun belongs to French collector Cyril Malzac who took the photos. It should not take too long to dismantle the handle, but I had to buy a big socket wrench to undo the nose of the gun body which is of a large hexagonal form.