The most common hose length found on the primary SCUBA regulator is about {28 to 30 in | 71 to 76 cm}. For many divers, this hose is too long and will cause the hose to "bow out," and create unnecessary drag and tug on the mouth. This makes for an uncomfortable dive, particularly in current. Some divers and even manufacturers attempt to improve the situation by making the hose even longer and perhaps adding a 360° swivel - which usually makes the problem even worse. Many of our our experienced divers choose the slightly shorter length of a {26 in | 66 cm} flex hose, feeling it is more comfortable with less drag and pull.
Increasingly we see our experienced single tank divers using a {40 in | 1 m} hose routed under their arm with the primary regulator on 90° swivel and use a shorter {22 in | 56 cm} hose for the backup regulator. The backup regulator is hung on a necklace directly below the chin. The { 40 in | 1 m } hose is also the common choice for the alternate regulator used on traditional sport diving "octopus" configurations. It is the most popular length for technical diving stage and deco regulators as well.
Many advanced divers and instructors believe the common hose lengths are too short in out-of-air situations and now use a much longer hose, often { 60 in | 1.5 m } for those who dive open water exclusively. Technical divers have adopted a length of { 84 in | 2.1 m } for overhead environments.