With five-eighth Johnson Peri bagging a hat-trick, the visitors crossed for nine tries and led 22-4 at the break.
This was the second consecutive game the Swords had conceded 50 points and their chances of securing a victory this season now look bleak.
Their four defeats so far have been by an average of 42 points, with remaining fixtures against defending champions Akarana Falcons and unbeaten competition leaders Canterbury Bulls leaving little hope of salvation.
Wai-Coa-Bay Stallions 50 (Johnson Peri 3, Caleb Heke, John Koko, Hohepa Monk, Hone Love-Henry, Terry Kapua, Daley Rata-Makene tries; Hayden Karena 7 goals) Northern Swords 4 (Ross McFarlane try); HT: 22-4.