The Solar Sailors
This position is the most misunderstood by non-sailors. In works of fiction written set aboard a ship, persons in this rotation are inevitably cast as brutish thugs. This stereotype is not mitigated by frequent images of crewmembers all modestly armed next to one person inevitably carrying a long weapon of some sort.
In truth, this position requires a unique type of person. They must be physically capable of on-board security concerns, intellectually capable of the electronic requirements of the communications equipment, and professionally competent in the standards and practices of multiple systems. And they are generally multilingual.
Security needs on a ship are rare and generally limited to interpersonal disagreements. Guests or passengers all receive a security check once per shift as well. In cases of piracy it is the munitions rotation that handles whatever response is decided, including dispensing small arms, which are generally locked away.
External threats to the ship are also the responsibility of the Munitions rotation. Most space debris is deflected from the path of the ship by the magnetic field generated by the sail. Larger objects such as asteroids and rogue planetoids can be detected and avoided. However, there are some bodies that are too large to be deflected. These are generally destroyed or pushed out of the way by large pulse lasers on the front of most ships. These lasers are powered by rechargeable cells that draw power from the energy deflected by the sails themselves.
It is not a great leap of logic to see these lasers used offensively, and inter-ship combat generally involves one of the two ships trying to get these weapons trained on their opponent. Because they are needed for navigation, and their limited availability of use until recharged, the deflector canons are not used until a crippling blow assured.