The Triangle 20 is a recreational keelboat built by Grampian Marine in Canada, from 1961 to 1963, with 75 boats completed. It was also sold in the US by the designer's company, Triangle Marine. It was sold complete or as a kit, for owner completion.
The fibreglass hull has a raked stem, a plumb transom, a keel-mounted rudder controlled by a tiller and a fixed stub long keel, with a retractable centreboard. It has a draft of with the centreboard extended and with it retracted. It has a hull speed of .
The design has sleeping accommodation for two people, with a double "V"-berth in the bow. The galley is located on the starboard side, just forward of the companionway ladder. The galley is equipped with a two-burner stove and an ice box. The head is located opposite the galley on the port side and includes a sink that drains into the toilet. Cabin headroom is .
It has a fractional sloop rig.