Mechanically, the device is simple: the only moving parts are the spear shaft and the rubber tubing. A loop of tubing is attached to a block of material, often wood, with a hole drilled in it which is slightly larger in diameter than the shaft. The shaft is placed in the hole, notched in the loop and pulled back, tensioning the tubing. When the shaft is released, the tubing propels it forward, faster and further than a diver could by hand.
The Hawaiian sling has some similarities to spearguns and polespears, in that all are powered by energy stored in rubber tubing. However, it occupies a middle ground between the two; the sling is somewhat more powerful than a polespear and offers a much more comfortable grip, but is less powerful than most spear guns. Like a pole spear, the diver must exert force on the shaft to keep it from releasing, whereas a spear gun has a trigger mechanism to accomplish this. Hawaiian slings are especially popular among divers who want a more challenging hunt, or those operating in areas where triggered spearguns are banned, such as the Bahamas, and Okinawa, Japan.
- "Hawaiian Squid-Hook Sinkers and Sling-Stones", J. Edge-Partington, Man, Vol. 17. (May, 1917), pp. 79-80.