Seven were built between 1903 and 1906.

As of 2020, the yachts are 117 years old.

Alfred Mylne designed the seven yachts.

The total voting population in the Republic's inhabited islands is just over 2,600 people, according to the Department of Housing.

Dublin Bay Sailing Club (DBSC) commissioned the boat to encourage inexpensive one-design racing to recognise the success of the Water Wag one-design dinghy of 1887 and the Colleen keelboat class of 1897.

Estelle built by Hollwey, 1903; Garavogue built by Kelly, 1903; Innisfallen built by Hollwey, 1903.; Maureen built by Hollwey, 1903.; Oola built by Kelly, 1905; Naneen built by Clancy, 1905.

Overall length- 32'-6', Beam- 7'-6", Keel lead- 2 tons Sail area - 600sq.ft

The first race took place on 19 June 1903 in Dublin Bay.

They may be the oldest intact class of racing keelboat yacht in the world. Sailing together in a fleet, they are one of the loveliest sights to be seen on any sailing waters in the world, according to many Dublin Bay aficionados.

In 1964, some of the owners thought that the boats were outdated, and needed a new breath of fresh air. After extensive discussions between all the owners, the gaff rig and timber mast was abandoned in favour of a more fashionable Bermudan rig with an aluminium mast. Unfortunately, this rig put previously unseen loads on the hulls, resulting in some permanent damage.

The fleet was taken out of the water in 1986 after Hurricane Charlie ruined active Dublin Bay 21 fleet racing in August of that year. Two 21s sank in the storm, suffering the same fate as their sister ship Estelle four years earlier. The class then became defunct. In 1988, master shipwright Jack Tyrrell of Arklow inspected the fleet and considered the state of the hulls as vulnerable, describing them as 'still restorable even if some would need a virtual rebuild'. The fleet then lay rotting in a farmyard in Arklow until 2019 and the pioneering project of Dun Laoghaire sailors Fionan De Barra and Hal Sisk who decided to bring them back to their former glory.

Hurricane Charlie finally ruined active Dublin Bay 21 fleet racing in August 1986. Two 21s sank in the storm, suffering the same fate as a sister ship four years earlier; Estelle sank twice, once on her moorings and once in a near-tragic downwind capsize. Despite their collective salvage from the sea bed, the class decided the ancient boats should not be allowed suffer anymore. To avoid further deterioration and risk to the rare craft all seven 21s were put into storage in 1989 under the direction of the naval architect Jack Tyrrell at his yard in Arklow.

While two of the fleet, Garavogue and Geraldine sailed to their current home, the other five, in various states of disrepair, were carried the 50-odd miles to Arklow by road.

To revive the legendary Dublin Bay 21 class, the famous Mylne design of 1902-03. Hal Sisk and Fionan de Barra are developing ideas to retain the class's spirit while making the boats more appropriate to today's needs in Dun Laoghaire harbour, with its many other rival sailing attractions. The Dublin Bay 21-foot class's fate represents far more than the loss of a single class; it is bad news for the Bay's yachting heritage at large. Although Dún Laoghaire turned a blind eye to the plight of the oldest intact one-design keelboat fleet in the world for 30 years or more they are now fully restored.

The Dublin Bay 21 Restoration team includes Steve Morris, James Madigan, Hal Sisk, Fionan de Barra, Fintan Ryan and Dan Mill.

Retaining the pure Mylne-designed hull was essential, but the project has new laminated cold-moulded hulls which are being built inverted but will, when finished and upright, be fitted on the original ballast keels, thereby maintaining the boat’s continuity of existence, the presence of the true spirit of the ship.

It will be a gunter-rigged sloop. It was decided a simpler yet clearly vintage rig was needed for the time-constrained sailors of the 21st Century. So, far from bringing the original and almost-mythical gaff cutter rig with jackyard topsail back to life above a traditionally-constructed hull, the project is content to have an attractive gunter-rigged sloop – “American gaff” some would call it.

The first DB 21 to get the treatment was Naneen, originally built in 1905 by Clancy of Dun Laoghaire for T. Cosby Burrowes, a serial boat owner from Cavan.