This post has been updated for the 2025-2028 Racing Rules of Sailing.
Rule 42, Propulsion, covers the permitted and non-permitted ways to change your boat’s speed while racing. Propulsion is sometimes called kinetics.
Many sailors don’t understand or apply the rule correctly, for several reasons:
- Lack of education and enforcement. On-water umpires and judges are used at high-level events. At lower-level events, self-enforcement is expected but often ignored, so average sailors have little incentive to learn the rule.
- Lack of experience, mostly because it matters most in small dinghies and may not be taught properly.
- Subtle interpretation, since the rule is complex and needs some judgment.
In this post we bring together the rule, World Sailing’s official Interpretations of Rule 42, Propulsion (World Sailing, May 2021), relevant World Sailing cases and video examples. Rule 42 is unchanged for 2025-2028.
Because Rule 42 is complex, we present it in two parts. Part 1 covers the interpreted terms, Rule 42.1 (basic rule) and Rule 42.2 (prohibited actions). Rule 42 – Propulsion: Part 2 of 2 covers Rule 42.3 (exceptions).
Video examples: clips from “Rule 42: Finn Class Common Breaches” (TheFinnChannel) and “Top 5 Rule 42 Mistakes” (Dinghy Racing Channel). Each clip starts at the relevant moment.
Rule 42 Terms
World Sailing’s interpretations define these terms (they are not Definitions in the rule book):
- Background rolling is the minimum degree of rolling caused by the waves.
- Body pumping is the movement of a sail caused by in and out or up and down body movement.
- A flick is the effect caused by body movement or pulling in or releasing a sail that is so abrupt that the normal shape of the sail is changed and almost immediately returned to the original shape.
- A pump is a single pull on a sail that is unrelated to wind or waves.
- Repeated means more than once in the same area on a leg.
- A roll is a single-cycle athwartship movement of the boat during which the mast goes to leeward and back to windward, or vice versa.
- Torquing is repeated fore and aft or rotating movement of the body.
- Yellow light area is a phrase used when it is not clear that an action is prohibited. It is unlikely that a boat in the yellow light area would be penalized, but it is possible. If the action is repeated, the likelihood of a penalty will rapidly increase.
Source: Interpretations of Rule 42, Propulsion (World Sailing, May 2021). These interpretations are still the current ones for 2025-2028; the 2025 rule book says “Interpretations of rule 42 are available on the World Sailing website.”
Rule 42.1 – Basic Rule
42.1 Basic Rule
World Sailing, Racing Rules of Sailing 2025-2028 (Study Version), rule 42. Read it online at racingrulesofsailing.org.
Except when permitted in rule 42.3 or 45, a boat shall compete by using only the wind and water to increase, maintain or decrease her speed. Her crew may adjust the trim of sails and hull, and perform other acts of seamanship, but shall not otherwise move their bodies to propel the boat.
Interpretations and Cases (Rule 42.1)
- BASIC 4 Except when permitted under rule 42.3, any single action of the body that clearly propels the boat (in any direction) is prohibited.
- Case 69: “Momentum of a boat after her preparatory signal that is the result of being propelled by her engine before the signal does not break rule 42.1.”
- Rule 42.3 (exceptions) is covered in Rule 42 – Propulsion: Part 2 of 2. Rule 45 (anchoring) isn’t covered here because it rarely comes up.
Video Example
Here is a simple example of propulsion prohibited by Rule 42.1. You’ll see others as we go through Rule 42.2.
Rule 42.2 – Prohibited Actions
42.2 Prohibited Actions
World Sailing, Racing Rules of Sailing 2025-2028 (Study Version), rule 42. Read it online at racingrulesofsailing.org.
Without limiting the application of rule 42.1, these actions are prohibited:
(a) pumping: repeated fanning of any sail either by pulling in and releasing the sail or by vertical or athwartship body movement;
(b) rocking: repeated rolling of the boat, induced by
(1) body movement,
(2) repeated adjustment of the sails or centreboard, or
(3) steering;
(c) ooching: sudden forward body movement, stopped abruptly;
(d) sculling: repeated movement of the helm that is either forceful or that propels the boat forward or prevents her from moving astern;
(e) repeated tacks or gybes unrelated to changes in the wind or to tactical considerations.
Interpretations (Rule 42.2)
- BASIC 1 An action that is not listed in rule 42.2 may be prohibited under rule 42.1.
- BASIC 2 A kinetic technique not listed in rule 42.2 that propels the boat, and is not one of the permitted actions covered in rule 42.1, is prohibited.
- BASIC 3 An action prohibited in rule 42.2 cannot be considered as permitted under rule 42.1.
- BASIC 5 An action listed in rule 42.2 is always prohibited, even if it fails to propel the boat.
US Sailing Appeal 128 (April 2025) makes the same point: “Movement by the crew that does not propel the boat does not break rule 42.1. Movement of the crew that results in an action listed in rule 42.2 breaks rule 42.2, regardless of whether the action actually propels the boat or not.”
Pumping – Rule 42.2(a)
- PUMP 1 Fanning is moving a sail in and out not in response to wind shifts, gusts or waves.
- PUMP 2 Pulling in and releasing a sail in response to wind shifts, gusts or waves is permitted, even if repeated (see rule 42.1).
- PUMP 3 Except when permitted under rule 42.3(c), one pump may be prohibited under rule 42.1.
- PUMP 4 A flick of a sail resulting from the sudden stopping of an eased sheet is permitted.
- PUMP 5 One flick of a sail due to body pumping, or a pump not permitted by rule 42.3(c), is in the yellow light area. Body movement that does not result in a flick of a sail does not break rule 42.2(a), but may break other parts of rule 42.
- PUMP 6 Repeated flicks of a sail due to body pumping are prohibited.
Video Examples
Rocking – Rule 42.2(b)
- ROCK 1 A roll of the boat caused by a gust or a lull followed by a corrective body movement to restore proper trim is permitted by rule 42.1.
- ROCK 2 One roll that does not clearly propel the boat is permitted.
- ROCK 3 Background rolling is permitted. Boat’s crew is not required to stop this type of rolling.
- ROCK 4 Adopting any static crew position or any static setting of the sails or centreboard, even when stability is reduced, is permitted by rule 42.1 and is not prohibited by rule 42.2(b).
- ROCK 5 A single body movement that is immediately followed by repeated rolling of the boat is prohibited.
Video Examples
Ooching and Torquing – Rule 42.2(c)
- OOCH 1 Torquing to change the fore and aft trim of the boat in phase with the waves is permitted, provided it does not result in pumping the sails.
- OOCH 2 Torquing on flat water is prohibited.
- In plain words, OOCH 1 lets you lean back as you climb the face of a wave and lean forward to accelerate down the back of it.
- College sailing is different. The ICSA Rule 42 guidelines say: “Except on a beat to windward, when planing or surfing is possible, unlimited ooching is permitted to initiate planing or surfing.”
- We didn’t include video examples for ooching and torquing.
Sculling – Rule 42.2(d)
For sculling, the interpretations say: “See interpretations of rule 42.3(d).” Sculling is generally prohibited, but there is an important exception in rule 42.3(d), covered with video examples in Rule 42 – Propulsion: Part 2 of 2.
Repeated Tacks or Gybes – Rule 42.2(e)
There are no official interpretations for this one. You may tack or gybe repeatedly in response to changes in the wind or for tactical reasons.
Summary
Use the wind and water, not your body, to make the boat go. If an action is listed in Rule 42.2, it’s prohibited even if it doesn’t propel the boat. When in doubt, you’re probably in the yellow light area, and repeating it makes a penalty much more likely.
Sources and Resources
- Rule 42 – Propulsion: Part 2 of 2
- Interpretations of Rule 42, Propulsion (World Sailing, May 2021) – the official interpretations quoted in this post
- Racing Rules of Sailing 2025-2028, Part 4 – rule 42 text, racingrulesofsailing.org
- World Sailing Judges Manual – racingrulesofsailing.org
- Video – Common Breaches of Rule 42 (Finn Class) – Sailing Scuttlebutt
- Video – Top 5 Rule 42 Mistakes and How to Avoid Them in Single-Handed Dinghy Racing – Sail-World
- Guidelines for On-the-Water Rule 42 Enforcement at ICSA Events – ICSA
