Question 1

A vessel constrained by her draught displays a cylinder shape by day. Roughly how does this differ in meaning from the day shapes for a vessel not under command (two balls) or restricted in ability to manoeuvre (ball-diamond-ball)?

Accepted Answer

A vessel constrained by draught (cylinder shape, Rule 28) is fully manoeuvrable in principle but limited specifically by the relationship between her draught and the available depth of water — unlike a vessel not under command (unable to manoeuvre at all due to some exceptional circumstance) or one restricted in ability to manoeuvre (limited by the nature of her work, e.g. dredging) These three categories (not under command, restricted in ability to manoeuvre, constrained by draught) each have a distinct cause and distinct day shapes/night lights under Rules 27 and 28 — distinguishing them helps other vessels understand why and how much a vessel's ability to take avoiding action is limited.

Question 2

Rule 5 (Look-out) requires every vessel at all times to maintain a proper look-out by sight and hearing, as well as by all available means appropriate in the prevailing circumstances and conditions — and this duty applies even when the vessel is at anchor in a busy anchorage.

Accepted Answer

True True. Rule 5 applies 'at all times' and to 'every vessel'. A vessel at anchor in a busy anchorage still needs an effective look-out to detect drifting vessels, dragging anchors, or approaching traffic that may pose a risk of collision or contact.

Question 3

Under Rule 6 (Safe Speed), a vessel fitted with a fully operational radar and ARPA never needs to reduce speed in restricted visibility, because the equipment guarantees early detection of other vessels.

Accepted Answer

False False. Rule 6 explicitly lists radar capability as one factor to consider, but also requires accounting for the state of visibility, traffic density, manoeuvrability, and the limitations of radar (range scale, sea/rain clutter, blind sectors). Even a vessel with excellent radar must proceed at a speed that allows proper and effective action to avoid collision and to be stopped within a distance appropriate to the prevailing circumstances.