Yes.

Rule 63,6(a) provides

The protest committee shall take the evidence, including hearsay evidence, of the parties present at the hearing and of their witnesses and other evidence it considers necessary. However, thecommittee may exclude evidence which it considers to be irrelevant or unduly repetitive.

That means that the protest committee must hear the evidence of every witness that a party brings to the hearing, unless it is irrelevant or unduly repetitive.

Rule 63.6(d) then provides

The committee shall then give the weight it considers appropriate to the evidence presented ...

Clearly some witnesses will have a relationship to a party that gives them an interest in the outcome of the protest one way or the other, and if their evidence conflicts with that of other witnesses, the protest committee should take this into account in the process of weighing and balancing up the evidence to arrive at facts found, but there is no warrant to automatically discount or ignore the evidence of who we used to call an 'interested party'.

It may well be that a protest committee will place greater weight on the evidence of an independent witness, than on the evidence of the parties,  their crew or their support persons, but this evidence should not be automatically discounted.

Judges Manual section F10 provides some guidance about hearing and evaluating evidence. 

In my opinion, judges should start with the proposition that every witness is telling the truth (within the limits of their observation,  understanding,  and recollection),  unless there is evidence to the contrary.

Witnesses come to protest hearings under the risk of severe penalties under rule 69 if they lie to the protest committee.

If judges start with the assumption that parties and witnesses are lying to the protest committee they will never be able to find facts and decide protests.

Turning to Jonathan's specific question about evidence of support persons about Part 2 incidents on the water.

My biggest reservation would be about the unlikelihood that a support person would be in a good position to directly observe relevant facts.  Think about where an umpire boat needs to be to accurately call an overlap, a gap, or a cross.  How likely is it that a coach boat, subject to the normal restrictions of keeping out of the racing area will be at the right angle and close enough to make those calls?

It may be appropriate for the committee chair to maintain very close control over such a witness, keep them rigorously to factual observation, and not allow them to engage in argumentation or attempts to interpret the rules.  This of course is in addition to making sure that support persons who are observers keep quiet and don't try to run the case for the party.

Bear in mind that if a parent or coach is to appear as a witness they cannot also be an observer, and must be outside the protest room all the time except when giving their evidence.

I'm not too worried about coaches or parents presenting video or photos.  Subject to the reservations in Appendix M, and Judges Manual F10.5, these, to some extent speak for themselves and, subject to those limitations can be quite helpful.

Great advice John.

I'm firmly in the club of not discouraging evidence or witnesses when reasonable. That said, my favorite question when calling crew, coaches, the third witness, etc is "Will this witness bring us anything we haven't yet heard?" Striking the balance between the party feeling they've been heard and not wasting time is a skill that comes with experience. Even at the top levels of the game, we often see repetitive evidence and calling crew members to say exactly the same thing we've heard. It's part of our service to the sport and important to the competitors viewing our decisions with legitimacy. 

I don't think I've ever experienced a party bringing an excessvie number of witnesses.

In terms of weighing evidence, evidence of two witnesses showing the same fact is better than the evidence of one showing another fact and so on.  We have no right to assume that witnesses will be partial or untruthful, so if one party wants to bring 3 witnesses and the other less than 3, those additional witnesses, assuming that they give consistent evidence, which is a big assumption, may outweigh the evidence of the other parties fewer witnesses.

As to the What's New question, I think it depends on where the weight of evidence is going, no party who has the weight of evidence going for him or her, and eventually wins the protest is going to complain about not getting a fair hearing because the protest committee in some way limited them bringing witnesses. OTOH, the party against whom the weight of evidence is running should be given every opportunity to bring more witnesses and build their case.

Bear in mind that you never know what a witness is going to say, pro or con the boat he or she comes from.

Just a quirk on rule 63.6(a).

It says
However, the committee may exclude evidence which it considers to be irrelevant or unduly repetitive.

How is the committee going to know that evidence is irrelevant or unduly repretitive until they have heard it?

John re: "How is the committee going to know that evidence is irrelevant or unduly repretitive until they have heard it?"

Good one! :-)

Ang