Thanks to America's Cup fever, the whole nation has now heard of "port entry advantage". But some may be wondering why it never seems to go our way.

First up, what the phrase actually means and why it matters. Port entry to the starting box is regarded as an advantage as this team can enter 10 seconds before the other team - another new rule devised over a year ago. The thinking around it was that given the speeds the AC72s are capable of, it would be too dangerous having them hurtling into the startbox at the same time and entering a traditional dial-up sequence.

The boat on port entry also has the ability to protect the leeward end of the startline, giving them a shorter run to the first mark. The outside boat has to try to roll over the top of them and be clear ahead before the three boat-length mark zone to gain right of way around the first mark.

How the port/starboard entries are allocated for the Cup races has become a bit of a head-scratcher as weather delays and postponements have put the system out of sync.

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The trick to getting your head around it is to think in terms of time-slots rather than days. The choice of who gets port entry for each race alternates each day. For example, if Team NZ get first choice at entry for the earlier 8.15am race, Oracle get to pick what side they enter from in the later race. The following day it swaps, so Oracle get first dibs on the early race and Team NZ the second race.

Where it gets confusing is when the second race is not sailed, as we have seen over the past few days. The allocation of port entry from the first race keeps alternating as usual, but the second race carries over.

So, because we haven't completed a two-race day since day six it is still Oracle's turn to have port entry for the second race of the day. Hence we had a confusing situation like yesterday where Oracle had the favoured port entry for both races.

The system was devised more than a year ago after teams raised concerns that the weather could vary drastically between the two races. It was thought that one team may be unfairly advantaged if they always had the choice of entry for the first race or vice versa, and so the decision was made to alternate it by race times. That decision was made back when the wind range was still 5-33 knots and it was thought postponements would not be an issue.

Still confused? Don't worry, we all are - even regatta director Iain Murray had trouble explaining it to us when asked to clarify the system.

But for those thinking that Team NZ seem to be getting the raw end of the deal, fear not. After yesterday's 12th race each team had six port entries.

Today Team NZ will be on port entry in the first race, while Oracle have it in the second.