Holland had adopted a different approach to the more upright centreboards of her lighter displacement opposition, with the centreboard case piercing the deck for’ard of the mast and the centreboard angling back at a reasonably acute angle.
|An unusual sight on an ocean-racing yacht - Harold Cudmore and crew fitting the centreboard to Silver Shamrock III before racing in the 1977 Half Ton Cup|
Silver Shamrock III needed to finish two places ahead of either Gunboat Rangiriri or Waverider in the long ocean race to win the contest. It was a light wind affair, and Silver Shamrock III gave herself the best possible chance by finding more breeze in the early stages and clearing out to an unassailable lead, leaving the regatta result hinging on the placings astern. Both Swuzzlebubble and Waverider held too close into the windless Botany Bay, which let Gunboat Rangiriri in for the second place she needed to win the title, finishing some three hours behind Silver Shamrock III, and just beating 2269, to take the Half Ton Cup from Silver Shamrock III by the narrowest of margins – just one point, with placings of 5/1/2/2/2 against Silver Shamrock III’s 1/4/3/5/1.
|Silver Shamrock III climbs out to weather after a start in the 1977 Half Ton Cup, with Newspaper Taxi (3223) to leeward and Gunboat Rangiriri astern (3426) (photo Ajax)|
The difference in performance between Gunboat Rangiriri, in the light corner, and Silver Shamrock III, in the heavy corner, or, as Farr put it at the time, “about as heavy as people want to go these days”, was minimal, and showed the IOR was coping with the differences in displacement concept, at least in the light to moderate conditions that prevailed off Sydney. They represented the development of two entirely different boat types to a similar pitch and were very similar in performance, and similar over a wide range of conditions, although Shamrock was faster downwind in the light, while the Farr and Davidson boats were faster downwind in the fresh. Between those extremes, observed Farr "they were so similar they really could have been the same design."
|Silver Shamrock III leads the fleet back to port, with Gunboat Rangiriri and Waverider astern|
|Silver Shamrock III battles her way out of Sydney Harbour in light and choppy conditions at the start of the 1977 Sydney-Hobart race|
It is not known whether Silver Shamrock III returned to Ireland, but she was replaced by a later, but less successful, version Silver Shamrock IV for the 1978 Half Ton Cup held in Poole.