Viv
Not being local to the island I do not know if the following is of any help
The stream forming the Claddagh is the Silver Burn which runs through Castletown into the harbour. The marshy area at low tide just up from the main harbour is called "the Claddagh"
From Fo'c's'le yarns: an uncensored edition of four Manx narratives in verse
By Thomas Edward Brown, Max Keith Sutton, Maureen E. Godman, Nicholas L. Shimmin

Archideaconal Wills 1661 #19, Patrick, of Jane Shimmin als Leece: Land at Claddagh-more.
The last will & testamt of JANE LEECE who departed this life ye 27th ffebruary 1661. Shee bequeathed her soule to God & her body to Christian burial. Shee left to her SONNE THO 20s due and ye Claddagh-more. It, she left him 5 pounds of lynnen yarne, and 4 pound of fflaxe unspun. Witnesses: Tho: Harison, Gilbert Mollecheif. This having relations to a contract betwixt Will Cannell & KATH SHYMIN, is referred to the judge temporall, & to returne his answer within 14 days.
Source www.isle-of-man.com/manxnotebook/famhist/wills/1661_js.htm