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Powerheads, Shark Defence Weapons

popgun pete

Well-Known Member
Jul 30, 2008
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1,551
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When I first started spearfishing sharks were always a topic of discussion, but divers rarely saw them except for the smaller ones and the various catsharks and ornamental sharks, including the Carpet Shark or the Wobbegong. The latter dozing on the bottom were like sacks of potatoes looking upwards with their beady eyes looking for a free meal and on occasion would appear ar the edge of your mask vision seeking to snaffle your catch. The bayonet tips on many early spearguns were to push away these nosy creatures without harming them. However at times big ones, usually females, would be very insistent and score a part of your catch if not all of it. Enter the 12 gauge shotgun powerhead made by a number of companies including Sea Hornet Australia. My long time dive buddy bought the Sea Hornet and being inquisitive about such things I dismantled it and drew the plans up for it, being a student at the time with one unit being Engineering Drawing. Long story short I found my old drawing which I thought I tossed out years ago. It is a large drawing so I had to stitch it together as a mosaic and given time I could do a better job of cleaning it up. Ideally the paper needs ironing or pressing to flatten it out.

One sunny day we were spearing off the headland at Woolgoolga on the NSW Mid-North Coast and a massive Wobbegong cruised in from below and was clearly after our fish. One of the other guys in our group was carrying the powerhead that I had machined up using my drawing, my buddy had his genuine one in his leg sheath. I pulled my snorkel mouthpiece out and said "That Wobbegong looks like trouble". Just then there was a dull thud, a feeling of pressure being hit in your guts and then he replied "Not any more it isn’t". Way down below our fellow spearo was ascending from the depths with the very limp Wobbegong in tow.

For those who are horrified at the bumping off of this large shark rest assured that we ate it and it was delicious. There was a lot to eat as it was over 6 foot, about as big as they get.

Being distracted by such high adventure at the time I never got my powerhead back from the guy who borrowed it and never saw him or it again.
Sea Hornet powerhead plans R.jpg
 
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The next step to carrying a powerhead on your thigh, always a hassle, was to build it into the gun and here we see the result. As powerheads are now illegal this one has had its firing pin sheared off rendering it entirely harmless. The ammo was ICIL 12 gauge Magnum shells, the longest shotgun cartridges we could lay our hands on. Even after painting around the brass rear section and the percussion cap with clear nail varnish and melting paraffin wax into the crimped cartridge nose they could still leak. Thus we had more than one cartridge fail to detonate with a big dent in the percussion cap. These duds were flung into the sea just in case they detonated when dried out. After going through a whole box of Magnum 12 gauge cartridges we decided to use the guns without being armed. The heavy bronze powerheads were offset by all the lumber in the gun, in fact they floated horizontally at the surface. They were good shooters and accounted for many fish with their 3/8” stainless steel shafts. No spring stainless shafts in those days. Speartips used were Undersee Mako. The twin grip handles were needed to haul the guns around when setting off on a new heading.
Chin mount Undersee homemade & Reefmaster front view.jpg

Custom Undersee & Reefmaster rear end.jpg

Chin mount powehead with barrel removed.jpg

Chin mount powerhead armed and ready.jpg

Just in case recoil when using the powerhead caused the sharp edged Undersee sear box rear from cutting a scoop of meat out of your hand a Perspex hood was fitted. Perspex does not last long in sunlight, so these would need replacing at times. The guns were retired after a couple of years and my gun was stripped back and revarnished with Brilspar Marine varnish, I had a big “Little Ships” pot of the stuff. A gum based varnish it went off after about twenty years and numerous timber guns.
Chin mount gun hood.jpg

Note that the shooting line was strung on both sides of the gun giving you four gun lengths plus the spear length for range, but at full line deployment the spear’s momentum would often peel a few more turns off the reel making the reel clicker sound. I shot a number of fish, I always got as close as possible before pulling the trigger, that the shaft, line slide and shooting line punched clean through the fish leaving it fluttering like a kite on the shooting line. Such fish could be a problem to haul in if they were still lively, but my buddy or I administered the coup de gras with other shorter weapons. A Mares “Miniministen” pumped up to near bursting, the hand pump shrieks in the final stages of pressurization, would soon add an extra hole in their noggins. Otherwise brain surgery was applied with appropriate knives or sharpened screwdrivers.
 
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Here are the offerings from Sea Hornet back in the day. There was a longer 12 gauge version that had port holes in the centre section that only fired when the weapon was completely flooded using a hydraulic plunger system, water being incompressible. They were not that popular and I only ever saw one brand new in the dive shop display case. The dive shop owner never let me take it apart, but I could guess what was inside that additional length section.
Sea Hornet Powerheads.jpg
 
In the USA explosive contact weapons are sorted into three categories; bangsticks, shark blasters and powerheads. The latter used a cartridge to fire a tip into the victim’s body enabling greater striking power with the shot, there were a number of versions. Herb Sampson had his own version that could fire multiple tips into the fish.

Herb Sampson powerhead.jpg

Sampson gun advert.jpg

Sampson powerhead instructions.jpg
 
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A little known fact is the twin rabbit ears line releases on a Prodanovich speargun are one for the gun’s shooting line and the other is for a second line which is attached to the explosive powerhead driven dart that was impaled in the fish, often striking the backbone with considerable force. A boon when band rubber was weaker stuff than we have today and guns needed more penetrating power for the most worthy of specimens to be landed.
Wally Potts Reel on Prodanovich gun.jpg
 
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The Swimaster Spearfisherman Magnum, copying the Prodanovich spearguns, had twin line releases as well. This is a big tube gun!
Spearfisherman Magnum by Swimaster R.jpg
 
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Jack Prodanovich patented a couple of powerheads. The problem to be overcome was to avoid the accelerative jerk of the spear out of the gun barrel detonating the power heads prematurely, thus a triggering system was required or a spring action dampening the acceleration onto the firing pin before the weapon actually hit the target. Photo supplied by Prodanovich expert John Warren.
Powerheads.jpg

This photo shows a variety of power heads used in the fifties, sixties and seventies, you can see that they are more than a simple tube with a round of ammo inside it. Not for shooting tiddlers!
 
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One idea to delay the firing of the power head until actual contact was made with the victim was to use an inertial firing pin with only a very light spring to hold it off the cartridge percussion cap. When the spear was driven from the gun with a mighty jerk the firing pin moved backwards in the head unable to be accelerated and then when the spear stopped its momentum this caused the inertial firing pin to slam into the cartridge base. This system had promise, but water inside the head would slow the inertial firing pin due to hydraulic forces opposing its movement, even with abundant relief ports. Ideally you want a void filled cavity for the inertial firing pin and a membrane to penetrate to the percussion cap, but this is a much more complicated device to make. Add to that the uncertainties of power heads firing due to damp ammo makes them a lottery at the best of times. Throwing unused ammo away after every dive becomes expensive.
 
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The next form of explosive gas generation was the liquid carbon dioxide dart, but that is another story.
 
Back in the early 60s I had a 12 gauge Sea Hornet when I lived in Hawaii. When my wife saw her first shark she made me buy one, and I made her carry it. It was very heavy and replaced a weight belt. The only times I ever used it on sharks were years later in Texas from the boat when I was getting my gear back from sharks hooked on rod and reel. It worked. But these days I suppose I would cut the wire leaders and let them have the hooks.
nancybang copy.jpg
 
They certainly did the job, especially on the handspear, especially as you could screw the handspear tip into the back end of the firing pin 5 replacing part 4 on the diagram. That removed the safety nut, but it was a more secure fitting than using the trumpet over the barbed or pranger heads. My powerhead had straight knurls on the body, otherwise it was a dead ringer for the Sea Hornet version which has a cross knurl. They are illegal here now and I guess they were either handed in or pitched into the drink at a suitably deep spot. Older powerheads would not have a licence, being purchased well before the regulations here changed. For several decades it was open slather, you could use anything.
 
From New Zealand my dive buddy imported an interesting .308 powerhead which was centrefire with a rimless ACP cartridge. This unit had the advantage that cartridges were admitted and ejected out of the front of the unit, there being no separate barrel to drop. I took it apart and drew it up, but never got around to making one. I have no idea what happened to the drawing, but I can remember how it worked. By rotating a knurled outer jacket or sleeve that revolved and slid a short distance on the main body you drove a half moon segment that clipped into the groove on the back of the ammo cases. Moved the other way the half-moon was withdrawn and pushing the rear plunger that your shaft connected to the spent cartridge would be pushed out. You shoved a fresh cartridge down the bore, rotated the sleeve and the new cartridge was installed and now locked in ready to go. It had a nut type safety to screw up and engage just like the Sea Hornet unit had, forget to use it and you might blow your hand off. The half-moon segment, that is not really quite the right name for it, had two tiny rubber cylinder springs to bias it on each side. It was a great unit and not that heavy, being comparable to the .303 military cartridge versions bulk-wise. The latter had a separate barrel to drop if you had a case of the fumbles or jitters. Being heavy compared to a naked spear they were flight trajectory influencers, so you fired as close as possible as your victim filled the panorama seen through your dive mask, your eyes no doubt as big as saucers from the shark’s point of view. Best shot was straight down from above going for the triangle apex set by the base created by the shark’s eye spacing. A hit there and it was power off or a case of the jiggles as helm control was lost. Never went deliberately looking for sharks and their speed and swimming ability totally eclipses ours, you would have to be crazy to actively hunt sharks. The poor old Grey Nurse with its curved and pointed toothy grin is a fish eater, it received a hiding back in the day with powerhead use. However the rule of the sea is “I am bigger than you”, so watch out if one wants your fish, or his/her fish as the shark sees it. They can have it!

I might add that my dive buddy sold this unit decades ago as it never was worth carrying, just another piece of gear that took up space and with its accompanying spare ammo which had to be thrown out regularly. Without eyes in the back of your head you cannot keep an eye out for sharks or you will be thinking of nothing else. The powerhead era was relatively short lived and divers were always anxious not to supply more nails for the sport’s coffin, there always being some “crusaders” who would like to give the sport the flick entirely. Remember seeing an advert's cartoonish drawing showing a fish crying while dangling on a hook, a propaganda item for sure.
 
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How's the intensity of the sound underwater while the shot is fired?

I haven't carried a bullet deploying setup while diving, but it's not that I haven't thought of it. In Hawaii, harming a shark is banned as of last year. That said, I'll do anything under self-defense. Encountering sharks for me is a common occurrence. Sometimes they pester me, and other times they swim right by. I've never had to do more than poke them away, but there were times I came close to doing more.
 
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Well I was hearing it through a 7 mm wetsuit hood, but it is a sort of BOOMPH which you can certainly hear, but it is not deafening, you really are not sure of direction either if you are not looking at the action. You feel a pressure wave in your body as the blast wave hits you, but you have the heavy body of the powerhead in front of you which must effect how it transmits. You are usually looking into the blast direction if you are doing the shooting and anybody from quite some distance around will hear it, even if they don’t feel it. My dive buddy could be a hundred yards away and always hear the thud of my pneumatic, mainly because it is different from the snap, crackle and pop you hear at times as background noise made by unseen sea creatures. Things go a big quiet when the powerhead goes off, but not for long. This is purely from memory as my powerheads were got rid of decades ago, in fact I ditched them before the rules changed as it was obvious that those days were over even before it became black letter law.

When testing the chin mount powerhead design we had one fitted to an adaptor to shoot it with a gun. The first time nothing happened as the powerhead failed to fire. The cartridge had not been hit by the firing pin, so my buddy reloaded his gun, took aim at a big weedy rock and pulled the trigger. The water in front of us was a boiling mess of sand, bubbles and scattered weed pieces as there was a mighty boom, but when my buddy hauled in the shooting line there was no powerhead, only the bare spear. We swam around and found the powerhead none the worse for wear, the threads had stripped out of the bronze adaptor. Just as well as it occurred to me the spear could have been returned to us on a reverse course with the jet propulsion created by the 12 gauge shotgun cartridge gases. I made all my own powerheads on my lathe, then took them down to the chrome platers.
 
Shark numbers are on the way up. A century or so ago whalers and sealers were scouring the oceans for blubber and oil that industry needed and they virtually starved out the big sharks. Any that swam up to a boat and looked threatening were eliminated, there were no shark lovers. When all that pursuit finally stopped we lived with the less sharky world that resulted, a new normal, in fact people thought the old-timers tales of ravenous inshore sharks were wild exaggerations. But the reality is surf culture and the golden diving years were all living in the death shadow created by those ruthless marine mammal hunters. Now things are getting back to normal, sharks are re-acquiring territories that once they were blasted out of, the coastal area that used to be a no go zone for sharks are being recolonized, that’s my two cents anyway.
 
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When I first started spearfishing sharks were always a topic of discussion, but divers rarely saw them except for the smaller ones and the various catsharks and ornamental sharks, including the Carpet Shark or the Wobbegong. The latter dozing on the bottom were like sacks of potatoes looking upwards with their beady eyes looking for a free meal and on occasion would appear ar the edge of your mask vision seeking to snaffle your catch. The bayonet tips on many early spearguns were to push away these nosy creatures without harming them. However at times big ones, usually females, would be very insistent and score a part of your catch if not all of it. Enter the 12 gauge shotgun powerhead made by a number of companies including Sea Hornet Australia. My long time dive buddy bought the Sea Hornet and being inquisitive about such things I dismantled it and drew the plans up for it, being a student at the time with one unit being Engineering Drawing. Long story short I found my old drawing which I thought I tossed out years ago. It is a large drawing so I had to stitch it together as a mosaic and given time I could do a better job of cleaning it up. Ideally the paper needs ironing or pressing to flatten it out.

One sunny day we were spearing off the headland at Woolgoolga on the NSW Mid-North Coast and a massive Wobbegong cruised in from below and was clearly after our fish. One of the other guys in our group was carrying the powerhead that I had machined up using my drawing, my buddy had his genuine one in his leg sheath. I pulled my snorkel mouthpiece out and said "That Wobbegong looks like trouble". Just then there was a dull thud, a feeling of pressure being hit in your guts and then he replied "Not any more it isn’t". Way down below our fellow spearo was ascending from the depths with the very limp Wobbegong in tow.

For those who are horrified at the bumping off of this large shark rest assured that we ate it and it was delicious. There was a lot to eat as it was over 6 foot, about as big as they get.

Being distracted by such high adventure at the time I never got my powerhead back from the guy who borrowed it and never saw him or it again.
View attachment 58949
To everything there is a season, and a time for every purpose under heaven.
 
There is never a season for becoming shark sh*t, so people need to wake up from the touchy feely mindset that has overtaken the world in recent times, the civilised world that is. Still red in tooth and claw elsewhere.
 
With the heavy “boomph” and “thud” of explosive weapons still ringing in their ears divers next turned to the carbon dioxide dart and the variations on that device. These Farallon darts were never imported into Australia, but I was sent a brochure many years ago having written for some info on them. I still have the brochure, so here it is having fortunately escaped being thrown out on a number of occasions.

The advantage of the expanding CO2 gas dart was it could inflate the shark and send it out of control to the surface, well that was the theory anyway. An alternate scenario was with its guts pressurized these would be ejected out of the shark’s mouth effectively turning it inside out. This was considered to be effective in putting the stoppers on any shark as hydro-dynamically it would be powerless to swim with its guts hanging out its mouth.
Farallon Darts 1R.jpg

Farallon Darts 2R.jpg

Farallon Darts 3R.jpg

Farallon Darts 4R.jpg
 
With the heavy “boomph” and “thud” of explosive weapons still ringing in their ears divers next turned to the carbon dioxide dart and the variations on that device. These Farallon darts were never imported into Australia, but I was sent a brochure many years ago having written for some info on them. I still have the brochure, so here it is having fortunately escaped being thrown out on a number of occasions.

The advantage of the expanding CO2 gas dart was it could inflate the shark and send it out of control to the surface, well that was the theory anyway. An alternate scenario was with its guts pressurized these would be ejected out of the shark’s mouth effectively turning it inside out. This was considered to be effective in putting the stoppers on any shark as hydro-dynamically it would be powerless to swim with its guts hanging out its mouth.
View attachment 59140
View attachment 59141
View attachment 59142
View attachment 59143
Wow, that's interesting stuff. I'm sure whatever it did to the shark, it couldn't have been comfortable. Does the dart detach and allow the CO2 to continue pumping the gas inside? I guess it would depend on how fast the gas exists, but I'm thinking the shark would almost instantly jerk away not allowing much gas to enter.
 
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