Band Length Defined for Circular Speargun Bands
Because the conventional way of stating band length is the most widely used and is the number that most people use when looking for speargun bands, the length in the band title on our site is the conventional nominal length for circular speargun bands with beveled ends. If the ends are not beveled or a special terminal is used such as the NTR Insert, the titled length will be that of the beveled band with the conventional length that approximates the same performance. In other words, and perhaps more clearly stated, the active rubber length will be approximately the same for two bands of the same nominal length on spearitco.com, even if the different end finish or terminal used makes the actual rubber portion length slightly different. Here is an example of how this might affect your selection of band size:
Example: The manufacturer of your speargun specifies 20 inch bands. They use a long gradual bevel on the band ends that shortens the active rubber by about 2 3/4 inches from it's nominal size. In other words, even though the nominal length for the band is 20 inches, the length of the active rubber is 17 1/4 inches. You have several choices on how to select your band. Starting with the least accurate:
You can order a Spearit 20 inch band which for most people will be sufficiently close in performance. There will be a some difference, however, because the Spearit band only has about 1 3/4 inches of inactive rubber which translates to 18 1/4 inches of active rubber. Again, for most people this is sufficiently close but if you want to more accurately match the performance of the stock bands, you can.
If you know the active rubber length for the band you are replacing or you have one on hand to measure, you can come within 1/4in of matching it on spearitco.com. This is because in addition to the nominal band length in the title we also provide the necessary information to convert the nominal length to the active rubber length for our bands. Therefore, because our custom bands are sized in increments of 1/2 inch, we have a band within 1/4 inch of the active rubber length of the band you are trying to match.
- The last and most accurate option is to make the band yourself, being careful to keep the active rubber length the same regardless of how you terminate the ends of the rubber.
The chart below shows what nominal length means for a Spearit standard beveled circular band and how the inactive and overall rubber length changes for bands with other termination types but the same nominal length while the active rubber length remains the same.