The Sarnians lifted the silverware after winning both the triples and pairs events, while finishing all-square in the singles.
In the triples, skip Will Ceillam’s team started well, leading 11-0 after five ends.
However, the hosts kept plugging away and reduced the arrears to 14-11, before at one stage going three points in front thanks to some excellent drawing by Adam Clark.
But Guernsey held their nerve and it was Ceillam who delivered a superb last-gasp wood to seal victory for his side.
In the other triples contest, Kris Bichard’s rink, which featured his brother, Shaun, and Ben Marley, recovered from a slow start to take the game 17-11.
The doubles saw the event’s only female competitor, the Isle of Wight’s Kati Allen, in action alongside Sam Lines. But the mixed pairing couldn’t see off the Bichard siblings, who took the clash 23-18.
Ben Mackett and Travis Miller scored a victory for the Isle of Wight over Michael Le Page and Todd Priaulx (24-14), but Ceillam and Marley sealed another success for the visitors, 21-17 over Paul Attrill and Clark.
Priaulx and Shaun Bichard got Guernsey’s singles challenge off to a flying start with early victories, before Attrill, Lines and Mackett hit back for the UK outfit – Mackett whitewashing Marley 21-0.
But the Sarnians weren’t finished and it was left to Kris Bichard to earn a share of the spoils with a comfortable 21-13 win over Allen.