You are arriving in port and are assigned to anchor in anchorage circle B-4. It has a diameter of 500 yards and your vessel’s LOA is 484 feet. If you anchor in 8 fathoms at the center of the circle, what is the maximum number of shots of chain you can use and still remain in the circle?

There are two ways to solve these kinds of problems. One is to use the maneuvering board. The other is to use geometry.

The preliminary steps are the same for each:

- Divide the diameter of the anchorage circle in half. The position of the anchor will be at the center of the circle so we only need to use half.
- Since the anchorage is described in yards, convert it (and everything else) to feet. Multiplying by 3, 250 yards turns into 750 feet.
- Convert the depth of the anchorage to feet. There are 6 feet in a fathom so, 6 x 8 equals 48 feet.
- Using the diagram, draw a line out to 750 feet (the radius of the anchorage).
- Subtract the length of the vessel from that 750 feet, because no part of the vessel can extend beyond that 750 feet. 750 minus 484 = 266.
- Go to 266 feet on the radius line and draw a line from there to the depth under the center (48 feet). The length of that line divided by 90 (feet in a shot) will give you the number of shots.

A second way to do this is by using the Pythagorean theorem which says in this case, if you square the depth of the anchorage and add to it the square of the radius of the anchorage minus the length of the ship (266 feet), it will give you the square of the chain length.

Here, 48

^{2}(2304) + 266^{2}(70756) = 73060The square root of 73060 (√73060) = 270.29 feet, which, when divided by 90 feet, equals 3 shots.

Finally, there is one other slightly lazy way and it works on all the problems when the depth is pretty small relative to the size of the anchorage. Simply take the difference between the radius of the anchorage and the length of the vessel. Divide that answer by 90 and you’ll get close enough to the answer.

The reason this works is because the angle involved is so small that there is relatively little difference between the length of the chain and the length of the radius of the circle minus the length of the ship. It is a lazy way and it works on all the problems currently encountered in the USCG examinations. Try it.

You are arriving in port and are assigned to anchor in anchorage circle B-4. It has a diameter of 600 yards and your vessel’s LOA is 525 feet. If you anchor in 10 fathoms at the center of the circle, what is the maximum number of shots of chain you can use and still remain in the circle? | |

A. | 6 shots |

B. | 5 shots |

C. | 4 shots |

D. | 3 shots |

Answer (C) |

You are arriving in port and are assigned to anchor in anchorage circle B-4. It has a diameter of 700 yards and your vessel’s LOA is 600 feet. If you anchor in 11 fathoms at the center of the circle, what is the maximum number of shots of chain you can use and still remain in the circle? | |

A. | 4 shots |

B. | 5 shots |

C. | 6 shots |

D. | 7 shots |

Answer (B) |

You are arriving in port and are assigned to anchor in anchorage circle B-4. It has a diameter of 550 yards and your vessel’s LOA is 449 feet. If you anchor in 9 fathoms at the center of the circle, what is the maximum number of shots of chain you can use and still remain in the circle? | |

A. | 6 shots |

B. | 5 shots |

C. | 4 shots |

D. | 3 shots |

Answer (C) |