Learning the SPRAT Curriculum: Deviations

In order to prevent abrasion related damage to your rope system, avoid hazards, or fix yourself into an efficient work position, a deviation (SPRAT definition: The use of a directional anchorage system to deflect a two-rope system from the fall line) can be used to redirect the path of the ropes from the anchor points. If you’re working in suspension on a particularly high structure, and there’s a fair distance between you and the anchor point (with no obstructions in-between), you may use one or several deviations to help fix your position – that way your ropes won't be jostled about by the wind.

One of the main benefits of using a deviation, is that it can be rigged for rescue, whereas a re-anchor cannot. However, a re-anchor may be the safer option if you find that a large angle is being created between your anchor points.

There are two different types of directional anchor systems (SPRAT definition: An anchorage system where a rope passes through an anchorage connector, such as a carabiner or pulley):

1. A single-directional anchor system is acceptable if there is no safety consequence of its failure, and deviates the ropes (or working line alone) by a small angle. It’s generally used to help keep the rope in a static position, or to gently adjust your positioning.
   • This is not a good choice for avoiding a hazard, and should only be used if there are no catastrophic consequences related to its failure.
2. A double-directional anchor system has two anchorage systems, and deviates the ropes by a larger angle and distance. It’s often used to avoid hazards, like sharp edges or hot surfaces.
   • In case of deviation failure, the additional anchor and the connection components that are part of the system, protect against the failure of any one item that would lead the rope tech to swing into a structure or other personnel (an out-of-control swing), or that would cause the rope to make contact with that sharp edge you were avoiding.  

During your SPRAT Evaluation, ALL LEVELS (*see below if you're a L3) will be asked to demonstrate competence ascending and descending past a directional anchorage system that deviates the fall line of a two-rope system by no more than 20 degrees -- the deviation should be as close to 20 degrees as possible, and should be more than 3m from the ground.

There should also be a minimum of 3m of distance between the directional anchorage system and the top anchorage system (SPRAT definition: Anchorage(s) and associated anchorage connector(s) used to interface within a main and or backup system), so that after the deviation has been passed you can continue ascending before completing a changeover and proceeding with your evaluation.

During this exercise, your SPRAT evaluator will specifically be watching to make sure that you:

• Understand which type of deviation is appropriate for which situation, and when another type of rigging would be more appropriate.
• Do not remove or replace equipment while passing the directional anchorage system. You should remain in either ascent or descent mode until the deviation has been passed. Only then can you complete a changeover. No change-overs, removing or replacement of equipment from the main or backup system should occur at the directional anchorage system.
• Take appropriate precautions to avoid an out-of-control swing -- this is one of the biggest dangers you'll need to guard against. 
• Do not use the directional anchorage system as a primary connection point. 
• Make sure to secure a knot in your ropes a suitable distance below the directional anchorage system, to aid your return on descent.
• Consider how a rescue operation would be performed.

L2 and L3 SPRAT techs should also understand how to rig a single and double anchor deviation.  

When rigging a deviation, pay close attention to how easily it will be to pass it while in ascent and descent mode. Some things you’ll specifically be paying attention to are: the angle and distance required to achieve the re-positioning, and the ease of use. Something else to keep in mind is anchor loading. The larger the Y-angle created by your anchors, the heavier a single load will become.

We’ll go into further detail on all of the above -- including the two different types of deviations and when to use them, and when to use single or double protection   -- during your training week. 

*This is one of 15 maneuvers on the L3 syllabus (coloured grey) that are primarily there for review. On assessment day L3 techs will be tested on only 50% of these items. 

Most Common Discrepancies to Avoid:

1. Unlocked anchorage connector on directional anchorage system – candidate above or below.
2. Uncontrolled lower away from directional anchorage system on ascent.
3. No knot below directional anchorage system to facilitate return through deviation.
4. If you use the directional anchorage system as a replacement for the main and back up systems, this will be considered an automatic fail. 

Additional resources to check out:

7.11 of the SPRAT Evaluation Guidelines for the source material for this blog (includes a very helpful diagram).

7.11 of the SPRAT Certification Requirements for a concise evaluation summary. 

This is part of an ongoing series, where we’re breaking down the SPRAT Syllabus and clarifying exactly what will be expected of you on your evaluation day. To continue exploring this series and learn more about SPRAT's Technician Evaluation Form, please click below: