Christian, by "changing the position", do you mean

Starting line is a gate (after the signal at least!) So marks on the line until the prep, first mark until the start, but that's pushing it a bit if the drop goes wrong etc, 

Craig - first mark until the start is a preference for some but not a rule.  In big classes, with shifty conditions,  I don't set the top mark until I get a clean start off.

Rule 30.3 and 30.4 need a triangle in the last minute before the starting signal therefore you need a nonmoving mark one. Otherwise boats need a fixed mark 1 when it’s importend for tacktics desiscions. For example in star class you have sometimes a distance from start to M1  over 2 nm. So it‘s up to you as the RO to decide when it’s importend. 

We had this discussion at a NRO seminar about 'trimming up' a gate.

RRS 34 also provides that if a mark is out of position while boats are racing, the race committee shall, if possible ... move it to its correct position ...

I take Andreas' point about Blac Flag and U Flag requiring a mark to be present (?in the water?), but otherwise, if the mark is out of position, say, still aboard a mark vessel, the race committee shall move it to its correct position, obviously, as soon as possible.

This approach relies on the SI telling us what the proper position of the mark is, that is 'windward' etc.

Rule 27.2 refers to a Start Mark.  Once a boat crosses the start line they are on Leg 1.  To more the Windward Mark #1, Rule 33 applies which states, "While boats are racing, the race committee may change a leg of the course that begins at a rounding mark or at a gate by changing the position of the next mark and signalling all boats before they begin the leg".  Since leg 1 has begun (and boats are already racing) as soon as the first boat properly crosses the start line, they can no longer move Mark #1 unless they are signalling a change of course at the time the boats start.  If they are not signalling then they can't change Mark #1 - it needs to be in place.  Or am I missing something?

This all assumes we are in a laid course in one of the usual configurations - trap, w/l etc - but in Keelboat raining a mark boat often leaves the starting area at the same time as the competing boats, to lay a mark many miles away and often not in a straight line, but following a coastline, waterway or river. Hence no rule in RRS as this would often be impractical and of no real use anyway. The RRS cover many and varied situations. 

Peter Reggio (Luigi) once asked at an Advanced Race Management Seminar in 2016, "When does the windward mark need to be set?" The answers from the students ran the gamut from before the prep signal to at the start.

The answer he was looking for was, "When they (the competitors) need it."

I've seen several instances with IROs (looking at you, PVM) having the windward mark visible in close proximity to it's final position, but not set at the start - usually to tweak a target time, not so much a bearing.

The issue with 30.3 and 30.4 ("requiring" a fixed weather mark) is non issue. Given a 0.3 nm starting line and a 1.5 nm first leg, the interior angle of the triangle is 84.3°. Changing the distance has a minimal effect on that (extending to 2.0 nm changes it to 85.7°). Changing the angle has about a 1:1 ratio on the interior angle (using the original dimensions (5° move to one side causes the interior angle to change approximately +5° on one side and -5° on the other).

I always ask myself the "Redress Question." I ask myself, "Is this likely to involve me being in a redress hearing?" If the probability is low, then I'm more inclined to do it.

Truly, the bottom line is what are you trying to accomplish? Hit a specific target time? Have a perfectly square course? It should all relate to the competitor experience - the question to ask yourself is, "Is what I'm doing making the race better for the competitors - and by how much?"  High-risk actions for minimal improvement is rarely a good thing. 

Well now, under rule 33 moving the windward mark while the racers are on the first leg is, I submit, clearly an improper action. However if a competitor wished to claim redress they also have to demonstrate that her score or place in a race or series [was] made, or may be made, significantly worse through no fault of her own. I suggest in many, even most circumstances where even a semi competent race team found a need to move a windward mark they would struggle to demonstrate that.

And I completely agree with Matt's last paragraph.

Craig, the RRS (and WS Cases) are an open rule set.

I don't see where it says you can't.

A competitor's perspective: In the recent ILCA Masters Worlds, a competitor (not me) tacked onto the starboard layline, a few dozen boatlengths from the windward mark. Then they saw the windward mark, a MarkSetBot, start moving to the right. Not a good thing from a fairness perspective, and not allowed under Rule 33.

But, per SI 11.2 (https://onb.ilca.roms.ar/ilca6ilca7masters2025/images/onbdocs/SAILING_INSTRUCTIONS_Amendment_5.pdf) the race committee could change the windward mark position +/- 10 degrees, at any time. This seems like a poorly written sailing instruction, since it opens the door for abuse.

Here's my second try at SI 11.2 -

11.2 – Change of Position of the Windward Mark (Mark 1).

The Race Committee may change the position of Mark 1 by no more than ±10° from its original bearing to maintain a fair first leg when a persistent wind shift of 10° or more has occurred. Any such change must be made and completed before the first boat has sailed more than 25% of the distance to Mark 1, based on the original course bearing. After that point, no further repositioning shall occur, except to replace a missing mark under RRS 34. 

The change shall be signaled by displaying flag C with repetitive sound signals from the Race Committee signal vessel or a designated mark boat stationed along the first leg, and, if possible, broadcast on VHF Channel ???. This changes RRS 33.

For context:
We recently ran the VX One North American Championship using a fully digital race management system. The entire operation — starting sequences, mark movements, course changes, tracking, and finishes — was handled by RaceSense and MarkSetBots, all controlled from a single signal boat. Apart from that, we had just one safety boat and a media boat on the course — and that was the full on-water team.