Portmadoc Sailing Club was formed in 1958 by a group of enthusiastic dinghy sailors based at Samson's Bay in the Glaslyn Estuary. Races and Social events were organised throughout the summer months from a marquee in a field behind the beach.
Trawsfynydd Sailing Club was formed in about 1962 as the Sailing Section of Trawsfynydd Power Station Sports and Social club. Many of the TSC members joined in the races organised by PSC.
Planning Permission was refused several times for PSC to build a permanent Clubhouse to replace the marquee. TSC had a site on building land but no Clubhouse. In 1964 the two Clubs amalgamated to form Portmadoc and Trawsfynydd Sailing Club and erected the Clubhouse and toilets on the present site.
Since then the Club has continued to promote the sport of sailing by providing facilities for dinghy and cruiser sailors alike. A race programme for both categories is organised each season but members whose interest lies in sailing for "fun" whether it be pottering about in the estuary or cruising to distant parts are equally well catered for. A limited social programme is arranged but the facilities lean predominantly towards the "do it yourself" member.
The freehold of the site was purchased in 1976, a couple of years after the toilet block was expanded to form the showers and changing rooms.
From the amalgamation until the Rules Revision of 1973 the Club finances were run on a cost split of half paid by 'Portmadoc' members subscriptions and half paid by Trawsfynydd Sports and Social Club. Over the late seventies and through the eighties the relevance of the Trawsfynydd connection reduced until by 1997 there were only three members with any Trawsfynydd connection and only one of those had continuous membership from pre 1973.
In 1997 it was found that there was an intention to form a boating or sailing club on the lake at Trawsfynydd as part of the development of leisure facilities following decommissioning of the power station. It was thought that there would be more confusion over the Club name if there was another club in the area with Trawsfynydd in its name. A proposal was put to the 1997 AGM to change the name to Porthmadog Sailing Club reflecting the current spelling of the town name and the location of the Club.