An interesting detail that certainly contributed to likelihood of a collision occurring on the startline such as the one that sunk Elliphunk is major line bias.
I realise that rum races are meant to be fun and not taken as seriously and that using permanent marks and start tower dramatically reduces the resource required by a club to run a race. It is also "part of the challenge" but it undoubtedly also increases the risk.
Why? Because rather than the fleet spreading right along the startline, they will all congregate at one end. For this particular start, on starboard close hauled a yacht would only be doing a little better than sailing along the line... as such many started on port with some possibly not even thinking that a few boats would still consider starting on starboard with such a heading. Late dips, congestion, and a risk of another boat being forced to tack (by other starboard tackers) cutting off your escape route are likely.
I suspect with rum racing the "fixed" startline won't change and you just need to think more about the possibilities...
However the following day for the RNZYS winter series the startline was between Te Kouma and a laid mark yet they pretty much replicated the rum race start of the day before in regards to angle and bias. To me this is absolutely crazy! If your going to bother to actually set a line at least try and make it a fair one. The tendency is to set the line square to the course... pretty much straight across the harbour. This inevitably creates a favoured end. Instead the race committee should angle the line to balance this with the objective being that there are valid reasons to start at any position along the line and potentially win the start. This will spread the fleet along the line and also result in more boats being "in the hunt" right of the start. It also reduces the chances of OCS, and recalls.
It's by no means just the RNZYS that is guilty of biased starts, virtually every club does it. This video below is a classic. Everybody wanted the windward end for a reaching start and it was carnage! SSANZ was lucky that there were no serious collisions. Some blame the sailors, and there is undoubtably some dumb stuff going on... but would this situation have happened if there was 20 deg more bias put into the other end of the line? I doubt it... well at least would be massively reduced. Same argument applies with class racing... if you get numerous general recalls generally the fleet is blamed for misbehaving. However I would put money on it that a large percentage of the time it's caused by a startline with too much bias. The other option is the line is fair but the course significantly favours one side, hence all the boats want to start at one end. The race committees challenge then is to put in enough deliberate bias to the line to tempt the fleet to spread right along the line.
So what's my point... Essentially Race Management can have a massive impact on risks of collision at the start. If they are going to "set" a startline as opposed to using permeant marks etc then they should at least try to make the start a fair one. Just setting a line and thinking it's up to the sailors to sort it out I believe is a little irresponsible. The more serious the event and the greater the number of competitors the more important this becomes.