Local boy Noel Fox surrendered the lead in the PGA EuroPro Tour event at windy Roganstown.
The joint overnight leader failed to build on his first round 66 as he carded a two over par 73.
Fox hit just four fairways and took 32 putts at the Swords venue as high winds sent scores soaring.
But he is still just one stroke behind English pair Christopher Hanson (72) and Robert Steel (69) and tied for third with Graeme Clark on three under par.
Gary Cullen (73), Alan Murray (72) and Brian McElhinney (72) are the next best of the Irish in a share of eighth place on one over par.
But Dundalk's Leslie Walker dropped five shots in his last six holes for a 76 that dropped him from fourth to 15th and six shots off the pace.