When I studied the dark arts of mechanical engineering, way back before recorded history, I can remember many class room discussions centered around factors of safety.
I thought perhaps a refresher on the principal may be helpful for some of our newer hangers.
In short, a factor of safety is a number you would multiply your maximum expected load by to account for the unexpected forces of mother nature and the foolishness of your fellow man.
Before material sciences matured to todays level, it was critical to assume a large enough factor of safety to account for all unknowns.
In calculating the needed strength of hammock materials and suspension components, a factor of safety is built in to most commercially available materials, except where maximum load numbers are used.
Differences in assumed factors of safety accounts for the differences between recommended load ratings for commercially available hammocks, such as a GT nano being rated for 250 lbs using 1.27 oz per yard material where a hennessey would consider the max load rating to be about 180. A 300 lb person may get away with using a 1.1 single, for example, by eliminating the safety factor assumed in most designs, however, material strength, sewing processes, etc can vary between two of the same hammocks, making one safe at this load and one not safe. It is generally impossible to see the differences by eye, so push the limits at your own risk.
It is important to remember that this rating does not equate to comfort level using a different material, which is yet another factor that hammock producers differ on.
On suspension components however, many times manufactures list the maximum working load of their materials under assumed conditions. Amsteel is
one such example.
We, when specifying components for our own hanging system, should always discuss the assumed factor of safety when we discuss our designs between each other.
I like to use the old tried and true factor of 10 when looking at suspensions, for example. Loading for 250 lbs at a 45 degree hang angle, for example, is calculated by taking 1/2 the load and dividing by the sin of the angle or 176 lbs in each line under static conditions, if you move around or bounce that load can go a lot higher
Accounting for these unknown conditions of bouncing, moving around, dog or child laying Down with you, etc, by multiplying this number by 10 would give you a minimum suspension component rated strength of 1765 lbs. Go lower at your own risk. Nicks and scratches can significantly degrade component strength as well, so you may want to double this if you are rough on equipment or taking a long hike.
Good hanging and let's be careful out there.