Options for Upper Point of Attachment - Overview
Ideally, every side mount diver would have a pad-eye securely imbedded in either side of their chest. This would provide for a single point of attachment that would simultaneously prevent the upper portion of a side mounted dive cylinder from moving backward or forward relative to the dive’s torso. Just kidding, but in the absence of such a fixture, limiting forward and backward motion of the cylinder valve must be accomplished through some combination of attachments between the top of the cylinder, the shoulder straps and/or back of the BCD.
There are various approaches employed to secure the cylinder at the upper point of attachment, each having a variety of pros and cons. Any of the approaches may be utilized in conjunction with the Slide Mount system provided the upper point of attachment prevents either cylinder from being tilted so far forward (greater than 45 degrees) that the two Slide Mount components can disengage. Apart from keeping the cylinder valve in a comfortable, streamlined position, some of these approaches also twist the cylinder to keep it snug against the diver’s torso at the lower point of attachment. This function is unnecessary with Slide Mount which establishes a hard point of attachment that already prevents the cylinder from twisting or flopping about.
Due to the variety of reasons for undertaking side mount diving, the differing requirements for thermal protection, the selection of side mount equipment and consequent configurations and even a given diver's body size and shape, it is incumbent upon every side mount diver to determine the equipment arrangement that best meets their individual needs. We at Sarabel Enterprises hope that the following information helps achieve that goal.
Option 1 – Shock Cord secured to upper back of BCD with Bolt Snap at free end
A suitable length of shock cord with a bolt snap at the free end is secured at chest height on either side to the back of the BCD. Each shock cord is first stretched around a cylinder valve and then secured to a D-ring on the shoulder harness with the bolt snap. This arrangement holds the cylinder adequately alongside the diver’s torso but makes no attempt to keep the cylinder neatly tucked back, out of the way behind the diver's shoulders. Furthermore, the bolt snap can swing freely behind the diver until attached and may be difficult to reach without assistance or using gravity to swing the bolt snap within reach. For a 42 in (107 cm) chest, this option requires at least 2 feet (61 cm) of shock cord per side to accommodate a knot at one end and a properly seized eye at the other.
Option 2 – Loop of Shock Cord with both ends at back of BCD
Independent loops of shock cord are established for each side at chest height. The ends of both loops terminate at the back of the BCD. The loop is first stretched around a cylinder valve and wrapped around the valve post opposite to the handle. When used in conjunction with bolt snaps at the lower point of attachment this arrangement twists the cylinder to lessen the distance between the cylinder and diver’s hip at the lower point of attachment when swimming in a belly down orientation. As noted earlier, this twist is unnecessary with Slide Mount. Even so, the configuration does help to keep the cylinder valve close to the diver’s torso, albeit further back than options that secure the cylinder valve to the shoulder harness. The downside is the long loop of shock cord may be out of reach behind the diver when trying to don a cylinder unassisted. Another downside is the requirement that the cylinder must have left and right valves with long posts that prevent the shock cord from accidently sliding off. Unfortunately, travel destinations seldom have cylinders with matching left and right valves and many cylinders have posts that are too short to accommodate this configuration. For a 42 in (107 cm) chest, this option requires at least 3 feet (91 cm) of shock cord per side to accommodate knots at both ends.
Option 3 – Same as Option 2 except the long loop is secured to the shoulder strap
To overcome the out-of-reach problem identified with Option 2, each loop of shock cord is secured to its respective shoulder strap by means of a short loop of cord that still allows the shock cord to stretch and retract as required. This provides ready access to the shock cord once the BCD has been donned. Apart from the same need for matching left and right valves with long posts identified in Option 2, there are two additional downsides. First, the loops can interfere with BCD donning and doffing, especially when wearing instruments or slates on your forearm. Secondly, the easiest method to grab the shock cord prior to stretching it, is to hook your thumb through the shock cord loop. Usually this isn’t an issue but dry suits that incorporate quick connect dry gloves often utilize a hard ring at the wrist that may prevent the diver from getting their thumb far enough back to reach into the loop. For a 42 in (107 cm) chest, this option requires at least 3 feet (91 cm) of shock cord per side to accommodate knots at both ends.
Option 4 -Same as Option 2 but with a bolt-snap that slides along each loop
This overcomes all of the issues raised with Options 2 and 3 but reintroduces the issues identified in Option 1, namely needing assistance or using gravity to reach the bolt snap and keeping the cylinder neatly tucked behind the diver's shoulders. With a bolt snap in hand, the shock cord can be stretched and wrapped around the cylinder valve before being secured to a D-ring on the shoulder strap. For a 42 in (107 cm) chest, this option requires at least 3 feet (91 cm) of shock cord per side to accommodate knots at both ends.
Option 5 – Secure bolt snap to cylinder valve
This option provides a benefit unavailable with any of the previous options, namely being able to loosely control the cylinder prior to final mounting. For instance, when shore diving it is advantageous to have both cylinders, fins and camera loosely secured to the diver so as to avoid losing anything in murky water, current or waves. When fully mounted, the bolt snap is secured to a D-ring on the shoulder strap. The bolt snap may be secured to the cylinder by means of a short loop of shock cord, thereby enabling easy removal when changing dive cylinders between dives. However the shock cord often stretches, causing the cylinder to hang downward and away from the diver’s torso when swimming in a belly down orientation. This can be partially mitigated by utilizing a shorter (medium) bolt snap and/or a Valve Choker (as shown), exclusively available from Sarabel Enterprises, to shorten the distance between the cylinder valve and diver's shoulder while maintaining the ability for easy removal when changing cylinders between dives. Even so, when employed in conjunction with bolt snaps at the lower point of attachment, each cylinder can still move several inches independent of the diver, so that each fin kick will result in a delayed jerk backwards. That independent movement becomes dangerous while walking on rocky shorelines or onboard dive boats because the cylinders are free to sway around unrestrained within several inches of arc and can easily cause the diver to lose balance and fall. Fortunately this issue is overcome by use of Slide Mount, exclusively available from Sarabel Enterprises, which restricts cylinder movement at the lower point of attachment.
Option 6 – Combine Options 2 & 5
As with Option 2, separate lengths of shock cord are secured to each side at the back of the BCD but this time the shock cords are secured near the top and bottom of the BCD. This avoids the problem of the loops flopping around while unattached and ensures they are easier to reach. As with Option 5, a bolt snap is also secured at each cylinder valve by means of either a short loop of shock cord or by using a Valve Choker (as shown), exclusively available from Sarabel Enterprises. After mounting a cylinder at its lower point of attachment by means of the Slide Mount system or bolt snap, the upper point of attachment is first secured by clipping the bolt snap at the cylinder valve to a D-ring on the shoulder strap. Then the shock cord is stretched forward and looped around the valve handle. In this manner, the bolt snap controls how far the shock cord can pull the cylinder valve back, thereby fully controlling the position of the cylinder valve relative to the diver’s torso. When used in conjunction with Slide Mount, the cylinders are fully restrained and become 'one' with the diver. For a 42 in (107 cm) chest, this option requires at least 2.5 feet (76 cm) of shock cord per side to accommodate knots at both ends.
