This is an 'educational web site' only. It is not a product endorsement or instruction manual. Any information here is derived from seeing this gun first hand and information on the U.S. Patent documents for this compound sling. 11/24/2004 JW
Although this sling is technically not what could be called a 'vintage speargun', it has features worthy of considering. This particular sling was made less than 15 years ago.
From the collection of Ron Mullins comes the 'Sea Archer'. This device is described on it's molded disks as a "Compound Hawaiian Sling". It uses a principal of drawing back the arrow almost exactly as one would do with a bow and arrow. The gun handle is underneath an aluminum tube. The arrow is inserted into the tube and exactly fits into an arrow receiver by the bowstrings. The underwater archer draws back the bowstring, aims at his quarry and lets go of the string. The band retracts the arrow string and ejects the arrow toward it's target.
There are two disks which have the bowstring line (heavy flexible monofilament nylon line) wrapped within opposing grooves. As the arrow is drawn back, each disk rotates in an opposite direction, stretching and wrapping the band around another groove on the top of each disk. It takes considerable force to draw back the arrow to it's fullest extent UNTIL the disk is rotated to 270 degrees. At that point the bands align near the axis of the arrow in a D-shape with a cam effect. The force on the bowstring is dramatically reduced at this point. The underwater archer is then able to effortlessly hold the bowstring, aim and shoot. This arrow has no slide ring, but does have a set of holes drilled through the spearshaft to fasten retrieving line. The tip of the arrow has a single flopper-wing after the point. The spearshaft is relatively thin in diameter, perhaps only 1/4 inch. It appears that this small gun would be quick to reload and fire.
A frontal view of the gun shows the layout of the aluminum gun tube and molded plastic nose piece. There is a tiny stainless steel pin on the left side of the nose of the gun tube. This pin functions to keep the nosepiece from slipping off the front of the gun.
Notice that there are two knurled knobs on the dorsal surface of the gun tube. These are locators for the two power settings for the band. The nosepiece is pulled forward and rotated 1/4 turn allowing the knurled knob to pass through. The nose piece is then turned to again notch into the second knurled knob. The nosepiece is now closer to the handle and the rubber is under less initial tension. This is equivalent to a lower power setting. In the above image you can see the small stainless pin on the aluminum gun tube nose.
On the back of the gun tube, directly between the center of the disks is a rectangular plastic block. Two solid aluminum arms project from this block outward. One faces up the other faces down. These hold line guides for the bowstring.
The arrow receiver is a short section of aluminum tube through which a section of clear vinyl plastic tube covers the monofilament bowstring. A copper crimp at each end of the vinyl tube keeps it aligned in the center of the bowstring. In front of the vinyl is a section of flexible rubber. It appears that the arrow receiver must protrude all the way through, but have internal cut-outs so that the rubber tube can be compressed between the fingers to 'hold' the arrow end as the bowstring is drawn back.
The above image shows that the rubber band is fastened through a ring molded into the disk. These bands follow an elevated (and sloped) groove in the top and bottom disks. The slope helps keep the band aligned on the disk. The method of attaching the monofilament is not obvious. It appears to just go into a hole at the end of the groove on the edge of the disk. It may not be obvious, but the monofilament is positioned around the full 360 degree circumference of the edge of the disk in retracting the band. The rubber band is about 25.5" in total length. It takes a rotation of about 270 degrees to attain the cam effect reducing the bowstring pressure.
The name plate says: Sea Archer, Miami, FL-USA, Compound Hawaiian Sling, US PAT 5125388. Since this patent is available to view on the web site of the U.S. Patent Office. It can be viewed by keying in the above number into the search box of the Patent Office web site at: http://patft.uspto.gov/netahtml/srchnum.htm
The view of the back of the Sea Archer illustrates how the aluminum rod arms are offset to accept the monofilament in the planes of the upper and lower disks.
A close-up view of the disk shows how the monofilament bowstring enters the disk. The actual terminal attachment point cannot be seen.
A close view of the band end shows another mysterious innovative method of anchoring the band. Please note that I did not open this fitting, but it appears that there is a nylon insert with some kind of screw thread (see horizontal line) which expands within the terminal end of the band. It appears that the 'bulge' formed by screwing in the nylon screw is what keeps the band from pulling free from the molded black plastic ring. In these images, the gum rubber band obviously needs replacement, as it originally came with the gun.
** NOTE* *
Thanks go out to Peter Currer in Australia for pointing out the mechanics of the cam affects the tension on the bowstring. This is explained on the U.S. Patent on this speargun. It always helps to read the instruction manual prior to using a speargun.
Many thanks go out to Ron Mullins who has generously allowed me to photograph this unique speargun for Internet viewing. Thanks again, Ron.
