Challenge regulations in full are from the MSA Blue Book, available here
Challenge Events (55)
23.1. Challenge Events must be organised in accordance with 1-4 and the following;
23.1.1. The aim of the event is to drive, tow and or winch a vehicle(s) to the various identified points within the competition site, the location of which will be indicated in the SRs.
23.1.2. At each location will be a means to prove that the vehicle has reached the location, this will be identified by a number to verify it is the desired objective and will be attached to a fixed point by a cable. A score card (or other device) (attached by the scrutineer in a consistent point on all vehicles) must be marked as proof that the location has been visited. The vehicle must negotiate close enough to mark the scorecard without detaching either component.
23.1.3. The SRs will specify whether the event is for single vehicles or teams of vehicles.
23.1.4. The SRs will specify whether there is a class structure and specify the eligibility requirements for classes.
23.1.5. The SRs will specify the start time, finish time and any penalty which will be applied for late finishing.
23.1.6. The SRs will specify any start order and the method arrived at for employing it.
23.1.7. The SRs will specify the values of each point visited or any formula which is used to calculate the value of each point visited.
23.1.8. In addition there may also be Special Tasks at certain locations which are worth extra points. These may take the form of driving, mental or physical tasks, these may involve the use of the competing vehicle or alternatively a vehicle may be provided for the task. Each task will be overseen by a marshal who will issue instructions and record the score.
23.1.9. The SRs will specify the number of Special Tasks available on the day and their maximum scoring potential.
23.1.10. Special Tasks may be timed to an accuracy of one second.
23.1.11. Where a winch cable or rope may be deployed the area of that section shall be no less than the length of the outstretched winch cable of rope and only competitors attempting the section and the observing official may be present in the Section. Where SRs require all competitors to use synthetic winch rope the width of this area may be reduced.
23.1.12. Winch cable and rope must be presented in a serviceable condition.
Winch Recovery (8)
46.1. The following regulations are additional to and take precedence over 24 to 35.
46.1.1. Details of the course, the manner of recovery, the maximum time for completion and the method of starting will be given at the Start.
46.1.2. Competitors will be allowed to examine the course prior to the start.
46.2.1. *The SRs will specify the number of vehicles and members in a team.
46.2.2. No more than three members will be allowed in each team which must nominate a Captain to be responsible for keeping any score-card issued and represent the team to the Clerk of the Course.
46.3.1. *At the Start and Finish, all team members must be correctly seated in their vehicle and all equipment must be in or on the vehicle.
46.3.2. Each team will be allowed a minimum of two attempts at the course.
46.3.3. The team completing the course with the least penalties as stated in the SRs will be the winner.
46.4.1. The Clerk of the Course may penalise or stop a team if it is considered their mode of recovery is likely to be dangerous to Officials, Competitors, spectators or natural terrain.
46.4.2. The Clerk can also award penalties for touching gates.
46.4.3. Once a winch vehicle and anchor vehicle have been manoeuvred into position, they must remain stationary whilst winching.
46.4.4. Natural anchorage points may be used, but must be protected from damage.
46.4.5. It is strongly recommended that all members of the team wear protective clothing during winching operations, ie overalls, gloves, eye protectors.
46.4.6. It is strongly recommended that competitors, other than the winch operator, should also wear a crash helmet to MSA specification.
46.4.7. All equipment, including cables, ropes, straps or webbing, shackles, blocks, hooks, ground anchors, winches, etc and vehicles must be presented to, and approved by, the Scrutineer prior to an event.
46.4.8. The Organisers may supply certain equipment.