Part of the Kenfig Patches system of shoals (Two Fathom Patch is to the west). Sailing Directions dating to 1884 provide a general description which does not refer to the Two and Three Fathom Patches, rather 'Kenfig and North Kenfig patches lie NNE from the last and are mostly rock, with depth of 3 to 4 fathoms over them. North Kenfig has but 10 feet water on it, and is about 2 1/4 miles from Hugo black buoy; its lies about a mile WNE from the entrance point from Hugo Black buoy and upon the same bearing 3 1/4 miles distant, are gravel patches of 4 fathoms. The space between the shore and the shoals described is studded with rocks, the least water over them being 2 fathoms, excepting off Rhwchian farm, where at least 4 cables distance form the shore, there is a little as 6 feet.'

Sources include:
Admiralty; 1884, Sailing Directions for the Bristol Channel, 4th Ed, pg115
Historic Admiralty Chart 1183-A2, RCAHMW Digital Collections sourced from the UK Hydrographic Office and published in 1839.

Maritime Officer, RCAHMW, September 2014.