The RSYS clinched victory 3-1 when Jarvin and his crew of 18-year-olds, Tom CLOUT and Sam NEWTON, incurred an instant penalty as they sailed from astern and drew level with Dunstan on the final spinnaker run to finish of the fourth flight.
In four Hardy Cup match racing events, Dunstan has twice won and twice placed second, starting off an international yachting career that sees him with an ISAF ranking of 33 as well as helming and crewing on Sydney 38s, Farr 40 and Etchells one design classes.
As a helmsman on Syd FISHER's ocean racer Ragamuffin in three Rolex Sydney Hobart Yacht Races he is following his father Jim, who has notched up a first and second overall with his 31-footer Zeus II in Sydney Hobart Races.
Michael DUNSTAN also received a bonus after today's win, with prominent Farr 40 One Design owner/skipper Richard PERINI, confirming Michael's place in the crew of his boat in next month's Rolex Farr 40 One Design World Championship in Sydney.
Twelve teams from Australia, Britain, Italy, Japan, New Zealand, Sweden and the USA contested the Hardy Cup, with donor Sir James Hardy, the former America's Cup, Olympic and World Champion yachtsmen among the spectators today.
Three Australian and one New Zealand team reached today's finals, with Michael DUNSTAN (RSYS 1) and Seve JARVIN (CYCA 1) going into the final.
Earlier, in the semi-finals, Dunstan outsailed the young Evan WARREN and the CYCA 2 team 2-0 and Jarvin beat the high ranked New Zealander Simon MINOPRIO from Vision Yachting, also 2-0.
Dunstan and his crew came through the Hardy Cup round-robins and finals with just two defeats, the result of aggressive sailing, good tactics that won them the start in each of today semi-final and final flights, and again today, the ability to outsail their opponents to windward in the southerly breeze that at times gusted to more than 20 knots on Sydney Harbour.
The lighter CYCA 1 crew twice overtook the RSYS 1 on the downwind legs of the finals and showed some spirited match racing fighting through tacks and gybes, but the greater experience of Dunstan and his crew came through in the end.
In the first flight of the best -of-five flight final, the RSYS 1 team almost lost their advantage when bowman Andrew Hutchinson toppled backwards of the side after a fast tack.
However, the powerful middleman, Wade MORGAN, caught his legs and dragged him back on board. 'We actually gained from that manoeuvre,' Dunstan quipped later.
The RSYS 1 team held their lead to win by a comfortable 15 seconds to go to a 1-0 lead as the breeze freshened to a steady 15 knots, with the two teams equalising their penalties.
Flight 2 saw a stalking game at the start, won by RSYS 1, followed by a spirited tacking duel, with Dunstan's all-round experience giving him another win and a 2-0 lead.
Dunstan and his crew controlled the start of Flight 3 and led around the first windward mark by two boat lengths, but the lighter CYCA 1 crew again were faster downwind.
Then, in a fast gybing and counter-gybing duel at the end to the spinnaker run, Jarvin and the CYCA 1 crew not only gained a vital inside overlap but saw the on-the-water umpires uphold their protest call against Dunstan.
Whilst Dunstan regained the lead on the second windward leg, he could not open up a sufficient break over Jarvin, who went on to win flight three as the RSYS 1 team took the penalty incurred earlier.
The umpires delayed racing after they found a hiking strap broken on the boat being used by the CYCA crew and order repairs before re-starting the flight.
When Flight 4 eventually started, Dunstan quickly gained control and in a close tacking duel won a penalty against Jarvin as the wind freshened to 20 knots.
The young CYCA crew fought back with aggressive tactics on the second windward leg, luffing the RSYS boat several times as they neared the weather mark and then setting off in hot pursuit of Dunstan on the final spinnaker run to the finish.
From three boat lengths astern, Jarvin steadily closed and gained an overlap three-quarters of the way down the leg, but in a spirited spinnaker gybing duel fouled the RSYS 1 boat.
Already carrying one penalty, Jarvin was forced to take both penalties immediately and Dunstan and his crew sailed to a runaway win in Flight 4, winning the 2005 Hardy Cup 3-1.
In the sail-off to third place, New Zealander Simon MINOPRIO and his Vision Yacht team won 2-0 against the CYCA 2 team, with helmsman Evan WALKER, a dinghy and catamaran champion, making an impressive debut in international match racing.