Myth busting
Steam Gives Way to Sail: Myth or Rule? What COLREGs Say
Published · Last checked October 2026
'Steam gives way to sail' is only partly true. Under Rule 18, a power-driven vessel must generally keep clear of a sailing vessel, but there are many exceptions. A sailing yacht must keep clear when overtaking, must keep clear of vessels fishing, not under command or restricted in ability to manoeuvre, must not impede large ships in narrow channels or traffic lanes, and becomes a power-driven vessel the moment its engine is propelling it.
Where the saying comes from
Under sail, a ship had limited ability to manoeuvre compared with a steamer, so it made sense for steam to keep clear. Rule 18(a) still reflects this: a power-driven vessel under way shall keep out of the way of a sailing vessel, as well as vessels not under command, restricted in ability to manoeuvre and engaged in fishing.
But the rule begins 'Except where Rules 9, 10 and 13 otherwise require'. Those exceptions, plus the rest of the hierarchy, are where the myth falls down.
When sail must keep clear of power
| Situation | Rule | What the yacht must do |
|---|---|---|
| Yacht overtaking a motor vessel | 13 | Keep clear: overtaking vessel always gives way |
| Narrow channel or fairway | 9(b) | Not impede a vessel that can only navigate within it |
| Traffic separation scheme | 10(j) | Not impede a power-driven vessel following a lane |
| Vessel constrained by draught | 18(d) | Avoid impeding its safe passage |
| Fishing, NUC or RAM vessel | 18(b) | Keep out of the way |
| Motor-sailing | 3(b), 25(e) | You are power-driven: follow power rules |
The motor-sailing trap
A boat with its sails up and its engine propelling it is a power-driven vessel under the COLREGs. By day it should show a cone, point downwards, in the forepart (Rule 25(e)); at night it shows power-driven vessel lights including a masthead steaming light. Many yachts forget both, and skippers then expect sailing-vessel treatment they are not entitled to.
Real-world sense
Even where you are technically stand-on, a large ship may not have seen you, may not be able to turn quickly and may be bound by its own constraints. Rule 2 requires every vessel to take any action needed to avoid immediate danger, and Rule 7 tells you to assume risk of collision exists when in doubt.
- Assume a ship has not seen you until it alters course clearly.
- Make your intentions obvious early, rather than holding on to the last moment.
- Use AIS and VHF to confirm the other vessel's intentions if needed.
- Remember 'not impede' duties start before any risk of collision exists.
For the full hierarchy see the right of way rules guide and revise in the COLREGs introduction lesson.