Speargun Rubber Band & Wishbone
Two factors affect a band’s power potential: stretch and diameter. All other things being equal, a 9/16-inch band provides less potential power than a 5/8-inch band. Adding additional bands increases the power potential in a linear fashion (i.e. two 5/8-inch bands yielding 100 pounds (45.4kg) of power potential. Each band, combined, yield 200 pounds (90.7kg)). Bands are frequently made of latex and come in diameters of 9/16-, 5/8-, and 3/4-inch. Some bands come with wishbones already installed, although some divers prefer to buy their own band material and install their own wishbones.
The selection of a wishbone should be based on the design of the spear shaft. Specifically how the shaft is designed to engage the wishbone.
Shafts fall into one of two main categories, those with notches cut into them and those with fins or pins welded onto them to engage the wishbone. There are also hybrids of the two where a small fin is welded in front of a recess ground in the shaft. For the purpose of choosing a wishbone these hybrid shafts equate to mini-fin shafts.
Most notched shafts are designed for use with metal wishbones. The size and shape of the notch determines which of the various metal wishbone types are compatible. V wishbones and cable wishbones will work with most notched shafts as long as the notch is of adequate size. The use of Spectra cord type wishbones is possible with notched shafts as long as the notch is smooth.
Shafts with fins or pins are designed primarily for use with cord wishbones. The size of the fin limits the diameter of the cord used for the wishbone. Mini-fin shafts have short low profile fins (3 – 5mm) and are usually designed to accept only one small diameter cord, like our 1.9mm Spectra, wishbone per fin. Shark fin shafts have larger fins (5 – 8mm) and will accept any size wishbone cord. Small diameter cord like our 1.9 or 2.5mm is usually adequate for shark fin shafts and will allow the engagement or stacking of multiple wishbones on one fin. Our 3mm Spectra cord, on the other hand, should only be used if there is a separate fin for each wishbone.
When choosing new or upgrading your wishbones, be sure to select the correct length of rubber for your speargun and also be sure that the wishbone being used is strong enough to cope with the rubber