Let's assume we reasonably know from the form/reports before the hearing that you're likely to be due redress for actions under RRS 1.1 and we're going to get that testimony. My next steps are as follows:

1. Engage with the best navigator I can find (I've generally engaged someone before the race to do this kind of work for me on a complex case. For simple stuff, I've used ChartedSails and my own skills). 
2. Get your track data from the race tracker, your onboard instruments, etc. For instance, if YellowBrick is the tracker, you can sometimes get data from YB with 1-minute resolution when the race is only publicly showing 15-minute resolution. Most onboard navigation systems can export the boat's track. 
3. Get the relevant GRIBS together for the times in question. 
4. See if there are any award(s) we should be nominating the boat to receive. 

-Now, we get the navigator to essentially pull together that once you resumed sailing, your percentage of time vs the "ideal track" with the GRIB after the incident was xx%. For this instance, let's assume you sailed at 92% of the ideal theoretical track after the incident. 
-Apply the GRIB and generate a route for you would have sailed if you hadn't stopped to help. This will get you to a predicted elapsed for the duration of the race. 
-Apply the 92% of polar to the remaining course had you not stopped and grant redress that equates to the finish time you've figured out. 
-Apply your rating and score the race. 

Important notes for the decision:
1. If eligible for an award (Arthur B Hansen Rescue Medal in the US) ensure the facts include all the relevant information for that award. For instance, from memory we put things like the wind speed, sea state, light conditions, etc. that we may not have otherwise had in the facts found. 
2. State that the boat and her crew are commended for their actions as a decision. 
3. In the decision, state that the PC or OA will be nominating the boat for the relevant award. 

I don't have much to offer on the question, although I suggest that looking at Volvo Ocean Race redress might be useful, but on John's scenario, were they entitled to redress because as a consequence of giving help they were compelled to retire?

RRS 61.4(c) provides (emphasis added)

If a boat is entitled to redress, the protest committee shall make as fair an arrangement as possible for all boats affected, whether or not they asked for redress. This may be to adjust the scoring (see rule A9 for examples) or finishing times of boats, to abandon the race, to let the results stand or to make some other arrangement.

I suggest that the protest committee should take all relevant evidence and then find a fact as to their best estimate of the actual (or possibly minimum or maximum) time lost by the boat entitled to redress, erring on the side of generosity in order to encourage compliance with RRS 1.1, and adjust the entitled boat's finishing time by that amount.

In the event of a boat retiring in order to comply with a SOLAS obligation, then I think the protest committee might consider giving average points.

Thanks Jim and I will study any Volvo cases. I my cited case we were not forced to retire, as we were directed to by the Philippines Coast Guard to go into the nearest port and stand-by (as our vessel is a registered S&R boat for the PCG)  - but for that (we did not in this case seek redress as not applicable), we would have gone onto to complete the race, once the distressed boat was in safer waters and able to manage. Had we gone on - I am just interested in the calculation meothod & mechanics if such a redress request was upheld (as we had only completed 50% of the race etc)...

Thanks John Allan..."average points" approach method

I think 'compelled' to retire is setting the bar too high.

The disqualifying condition in RRS 61.4 IS 'fault of her own'.  Performing a rescue duty, particularly under formal authority is not a 'fault'.

As a matter of interest, on our "SOLAS obligations?, in the actual case of mine, our knock-down was - masthead some 2-metres off of the water (we had harnesses and full-deck jacklines both sides and boat battened-down etc, and a steel boat with 48% balast ratio etc), and as the microburst was continuing to intensify - along with increased wave frequency (with current against wind affect going on): as the skipper / helsman onboard, with a group of young local trainees, I thought about turining back to better render assistance but concluded that we could have taken two more knock-downs doing that - so engine on, slowed boat to a crawl on a good sea-angle, to let them come closer to us, called other boat on VHF and told them to follow our track (about 500mtrs behind us - we monitored them with high pwoered binnoculars). If we had to go back to further assist or an abandon ship drill with the following boat, we most certainly would have without hestitation).

When I'm on a redress hearing committee I always ask the boat requesting redress to explain what redress they want and to justify what they are requesting. They can use any method(s) they like to justify the redress they are requesting. I would expect them to research the best method (e.g. trackers, average points, predicted VMG based on conditions, etc.) to justify the redress as they would probably know their boat, the circumstances and the conditions that affects their score better than anyone else. It would be for the PC to consider the merits of their argument to finally decide on the redress given.