"Aquamatic" Speargun Australia

In 1948 Trevor Davies decided to make a new underwater gun using his first coil spring powered effort as a basis for a weapon propelled by compressed air. Today this is something that we take for granted, but back then this was a completely new idea being developed independently in Sydney, Australia. Trevor reasoned that the long rear tube with the compression spring could be replaced by a pressurized cylinder with an inner barrel containing a sliding piston. In order to provide sufficient power the gun used a big diameter piston, high air pressure and a ratchet lever loading system on a specially notched for the purpose spear. Cranking the loading lever the spear was fed in short increments down into the gun until a sear pin clicked onto the shaft thereby retaining it. The line was rigged and the gun was then ready for action.

Only made on a small production basis the guns were never produced in large numbers and various modifications were tried in terms of the piston bore size and the profile of the rear tank.

Below is the engineering drawing and a simplified version showing how the “Aquamatic” is cocked ready for shooting.

The "Aquamatic" was in a sense a forward latching speargun, but with the grip handle and trigger mechanism being arranged as a mid-handle. A slim diameter barrel projected forwards of the grip handle as a guide for the balance of the spear length. The short power stroke with respect to the length of the spear was compensated for by the high pressure used as without the ratchet loading system you could never load it! The shooting line rigging was provided by a special reel which had a forward wand on which the line wraps were installed with a rear passive line release hook in front of the reel being friction loaded. This reel mounted on the front of the mid-handle just in front of the detent pin which also served as a safety device..

The following photo shows Trevor's brother George Davies, a champion spearfisherman, holding the gun alongside a luckless victim that had been blasted by the "Aquamatic".

This is an experimental "Aquamatic" where the rear tank has been replaced by three interconnected tubes which provide additional capacity, but with smaller diameter tubes than the original single tank. The balance of the gun remains the same.


The very first "Aquamatic" is shown below, this gun having a handpump connected to the rear, but yet to have a lever loading system. (Photos were supplied by Mel Brown).

Back in the old days Newcastle diver Bob Penfold bowled over this 80 pound Cobia with his "Aquamatic" seen here alongside the victim.