I should have thought the answer was as little as possible. Isn't involving law enforcement and the like a matter for the building owners/management? So is a decision on whether to eject any person from the premises.  A PC could only get in the way of the professionals. At the absolute most gathering names and addresses of any witnesses. Certainly couldn't hold any kind of hearing if any of the parties are intoxicated. Surely a misconduct hearing ought to wait until the dust has settled.

It would be up to the club, which may not be the OA to see if membership regulations were breached and for them to involve the police.

The protest chair  can do no more than collect some information and brief his team early morning.

He will soon be told to leave the club; the team is probably dispersed.

He needs a hearing to decide id a 69 should be brought, it is not their decision.

At his accommodation, the chair can plan and prepare an RRS 69 notice in case it is approved in the morning.

The boat owner's telephone number could be sought in case the owner needs to know about his crew member's actions and the possible consequences; he may choose not to take him to avoid endangering the boat's score.

Contact the protest team for an early meeting to discuss least an early (before race ) hearing is required.

With simple facts like bottle throwing and bad language no real need for an investigator, as few witnesses will be required

, and this simplifies matters.

As you are probably aware the IJ Seminar 20 Questions are to get you thinking about complex and unusual issues and refamiliarising yourself with some less used rules.  Your 'solutions' are not handed in or assessed, although the intelligence and diligence you demonstrate in the discussions may influence the senior IJ presenting in your favour.  It always helps if presenters think well of you and want to help you get along.

So, you need to describe how you would want the scenario to play out.  Don't forget to look at RRS M6.

You need to keep a sense of perspective:  it is a breach of good manners, it has no effect on the fairness of the competition and is not an issue involving protection of competitors from harassment, bullying etc.  While it is serious, and in the old money is undoubtedly gross misconduct, it is not World War 3:  it is at the lower end of criminality.

You do not need a 'qualified' investigator:  who you choose to investigate is up to you.

You do not need any legal advice to conduct a RRS 69 hearing.  There is no decision a protest committee can make under RRS 69.2(h) that can have any legal repercussions:  The only actions a protest committee can take under RRS 69.2(h) affect places in races at the event.  This cannot lead to, for example CAS proceedings for restraint of trade.  Of course the protest committee should exercise discretion in making any communications about the matter that may be defamatory (see RRS 63.6(c) and (d)).

Obviously this is a time-line problem.  The scenario opens after close of business and you need to fit in the procedures required by RRS 69.2 in between when you receive the initial information and when you want any penalty, such as exclusion from racing, to apply.  You will need to pay particular attention to:

and how this can all be fitted in to the racing schedule.

While it is not strictly a requirement, I would want to talk to the Regatta Chair or a senior Flag Officer or Board Member of the OA and find out how seriously they view the incident, and broadly, what they would like to see happen.  I would be cautious about placing too much reliance on what a staff manager of the host club tells you.

Just note the following: