The Royal Munster Yacht Club introduced the International 12 foot Dinghy Class to Ireland in 1923 when fifteen boats were ordered from the boatyard of James Pluck in Cobh (previously known as Queenstown). Before long these boats were being raced enthusiastically.
In October 1924 Captain Jimmy Payne represented the Irish Free State in the first ever World Dinghy Championship organised by the Brussels Royal Yacht Club. In his first competition outside Cork, Jimmy Payne achieved a convincing victory against strong competition from France, Holland, England, Belgium and Italy and returned home to a hero's welcome.
Captain Payne's homecoming
Report published by Irish Times newspaper in October 1924

Payne's victory meant that the club hosted the following World Dinghy Championship in August 1925. This time there were four competitors, representing the Irish Free State, Britain, Holland and Belgium. By the start of the third and last day Ireland and Holland were level-pegging with seven points each. This time Payne won the deciding event by 29 seconds from Bokre of Holland to secure overall victory and a magnificent silver trophy.

Captain Payne's trophy
In 2011, Mrs Eithne Payne presented the International 12 trophy,
won by her father-in-law Captain Jimmy Payne in 1925, to RCYC Admiral Peter Deasy
to become the season-long overall winner prize for the National 18 Class in Cork Harbour.
Photo: Bob Bateman

The 12-foot class soon became very popular in Ireland. In 1925 it was introduced to the east coast by the Seapoint Boat Club when six boats were built at Dun Laoghaire. In the following year the first of a series of competitions between the dinghies of the Royal Munster Yacht Club and the Seapoint Boat Club was held.

The class continued to grow in popularity throughout the 1930s. Fleets of professionally and amateur built boats multiplied in Baltimore, Crosshaven, Howth, Sutton, Clontarf and Seapoint (Monkstown, Co. Dublin). Over many years Championships were held in locations such as Lough Ree, Dun Laoghaire, and Cork Harbour.
The CORA Trophy
Originally presented to Sutton Dinghy Club by Norman Ross, owner of No. 8, Cora, the trophy was won outright by W.L.McClelland who later presented it to the Irish Dinghy Racing Association as the major trophy for the class. A condition of the gift is that the racing flags of the winning owner shall be painted on the face of the plaque.

The trophy, which depicts BRA 12 footer No.5, Dorado, being sailed in Dun Laoghaire Harbour by Terence Chadwick and his sister Joan, was competed for during the period 1945 - 1964.
The 2010 Irish Dinghy Championships
Ed Sarratt,Aiden Henry, David Sarratt, Gavin Johnson, Gail Varian, Geoff Sarratt, Aishling Costello,
George Miller, Ray O'Connell, Brian O'Connell, Billy Bebbington, John Walshe, Paul Gillespie.
The International 12s and the Dublin Bay 12s combined forces for this event at the Royal St. George YC, Dun Laoghaire. The racing was close with the single sail boats not falling too far behind upwind and possibly faster than the DB12s downwind. Both races were won by Gail Varian in her DB12. Following the success of this inaugural event, a race series for 12-foot dinghies will be hosted by Sutton Dinghy Club next year.
Hannah and Andrew Miller help their father to restore their 12' dinghy Pixie in Dublin.
12-foot dinghies and IDRA 14-foot dinghies at Sutton Dinghy Club in 1949.
Sutton Dinghy Club
'Sutton Dinghy Club (Dublin) has come a long way since it was launched early in May 1940, when seven International 12 ft. Dinghies sailed their first race under the new club burgee, which was (and still is) blue with a white silhouette of the International 12 ft. dinghy. Two "Twelves" are still owned and sailed by members of the Club, and the burgee is a reminder of those early days'
Excerpt from Sutton Dinghy Club website.
During the 1930s enthusiasm for the 12-foot dinghy waned at Howth, Malahide and Dun Laoghaire, and their boats dispersed, but most of them turned up again a few years later when Sutton Dinghy Club was founded. The class continued to thrive and race at SDC until the early 1960s.

The Irish Dinghy Racing Association was founded in 1946 with the express purpose of promoting and regulating the 12-foot class, which was at that time the largest one-design class in the country, and to adopt a 14-foot class for national use.

Today there are a handful of survivors at Sutton Dinghy Club and on the River Shannon.
Dublin Bay 12s
During the early 1970s, many Irish 12-foot dinghies were converted to 'Dublin Bay 12s' with the addition of a foresail and modifications to the cut of the mainsail.
A Dublin Bay 12 sailing in the Waterways Ireland Classic Boat Regatta    Dorado subsequently reverted to the standard International 12-foot Dinghy sailplan.
Irish fleet list