You talking about
these designs?
Those are my designs. Single tank offset is influenced by a number of additive factors.
The first is over all plate bend. DSS plates have a much flatter bend than most plates originally designed to mount doubles.
The depth of the center channel. DSS plates have a conventional style center channel, but it is far shallower that most plates originally designed to mount doubles.
Wing grommets. Most wings use a #3 grommet and a piece of resin reinforced webbing in the center panel. These grommets + Webbing are .25" thick. These grommets act to space the STA up away from the center channel of the back plate.
STAs all have some thickness, typically about 1/16, and they are designed so the cambands pass between the sta and the cylinder. Camband webbing is ~1/8" thick. STA's also require mounting bolts, typically a domed headed carriage bolt. These heads are also between the cylinder and the back plate. Often at least one camband passed over the head of these bolts, usually both do.
Starting at the back plate. Metal wing grommet, .25", STA metal, .06, Bolt head .18, Camband , .12 Total .61 or almost 5/8"
DSS designs us no STA, and our wings have no metal grommets. The molded rubber elements in the center panel of our wings are less than 1/8" thick.
Add to that a flatter plate, and much shallower center channel and the cylinder offset with a single tank is often at least an inch less than designs based on a doubles plate, that was *adapted* for use with singles by slapping on a Single Tank Adapter......
Having said that 95+% of the time I use mine with doubles.
Tobin