bluewater hunting and freediving An early Ron Mullins creation these divers claim it is the noise from the rapidly discharging shells that drive sharks away. 96 TAPE MEASURES AND SCALES Don’t forget these—they may be important for documenting your catch, especially on multiday trips. Some tuna are simply too large to weigh on a boat. Using the following formula, a tape measure and a calculator, you can accurately gauge the weight of both yellowfin and bluefin tuna. Measure, in inches, the girth of the widest part of the fish, and measure its length from the tip of its closed mouth to the fork in its tail. Square the girth and multiply it by the length. For the “tuna weight,” divide the product by 800. For example, calculate the weight of a tuna 87 inches long with a girth of 57 inches. The product of 57 x 57 x 87 divided by 800 is 353 pounds. ATTITUDES Bluewater hunting and freediving are demanding sports. The gear, relatively simple when compared to scuba gear, is still very important. The best divers learn how to fabricate or modify their own equipment. Most importantly, they evaluate every piece of gear and every modification with a view toward safety.