Rule 28: Vessel constrained by their draught
A vessel constrained by her draught may, in addition to the lights prescribed for power-driven vessels in Rule 23, exhibit where they can best be seen three all-round red lights in a vertical line, or a cylinder.
What this means:
Rule 28: Vessel constrained by their draught – Our plain English guide to help you understand & remember this rule.
Any vessel can be constrained by its draught; the bigger the vessel, the greater the draught, the deeper the water it needs.
The rules already provide for larger power-driven vessels when operating in narrow channels, and this is where we encounter them most. For this reason, the lights for vessels constrained by draught are optional when in a Narrow Channel or Traffic Separation Scheme.
When our path crosses with a large commercial vessel in open water, away from the coast and any narrow channels, it would not be constrained by its draught.
Day shape
A black cylinder *may* be displayed where it can best be seen. Apart from being optional, these are very hard to spot in practice. Our most likely sighting of a vessel constrained by its draught is in a narrow channel, so we must keep out of its way.
Lights
Three all-round red lights vertically *may* be displayed in addition to the size-appropriate lights for a vessel underway. However, our most likely sighting of a vessel constrained by its draught is in a narrow channel, in which case, we must keep out of its way regardless of whether it displays three red lights.
Switch between day and night to compare with the equivalent day shapes.
