If the fantail security watch issues a challenge and gets no response, what should be done to summon assistance?

The most appropriate action to summon assistance if the fantail security watch issues a challenge and receives no response is to sound a whistle. This method is effective because a whistle can carry sound over a considerable distance, making it an efficient way to alert others that assistance is needed. In a security situation, a whistle is also a non-verbal signal that can be recognized quickly by other personnel in the vicinity, prompting a swift response.

Using a whistle ensures that the situation remains controlled and avoids unnecessary escalation or panic that might come from yelling for help. It also maintains the security and order of the area, as the noise from a whistle is less disruptive than shouting or other loud noises, which could potentially alarm unauthorized individuals.

Alternative methods of summoning assistance, such as yelling for help or firing shots into the air, could lead to confusion or escalate the situation unnecessarily. Leaving the post to call the Officer of the Deck (OOD) may also compromise the security of that area, as it would leave the post unattended. Thus, sounding a whistle is the correct and safest course of action in this scenario.