McLay, 30, intends to remain in the Bay and will contract his services out to any club within the Hawke's Bay-Poverty Bay region.
"I want to see all clubs in the region do well," the Swim Hawke's Bay and Swim Hawke's Bay-Poverty Bay board member said.
"It was during the first week of the school holidays when we were in the South Island at the division two nationals with the Hawke's Bay-Poverty Bay team. When I saw how well the team worked that was the turning point and I decided to leave the Sundevils then," McLay said.
"Since coming to the Bay I've done a lot to get clubs working together more to become more regionally focused. I want to keep developing that and work with all the clubs and coaches ... Sundevils included," McLay said.
The former Wharenui squad coach in Christchurch pointed out he is keen to be involved in some capacity with a new "Super Rugby" type competition about to be introduced to the national scene. The country has been divided into four regions and Hawke's Bay-Poverty Bay is in the same region as Taranaki, Waikato and Bay of Plenty.
The other regions are an Auckland-based one which also takes in Northland, a Wellington-based lower North Island region and the South Island. After the short course nationals in September, teams from the four regions will compete against each other in Wellington.
McLay, who had his first head coach job at the age of 20, believes this competition will help the Bay's talented swimmers remain in the province longer.
"I think too many of our swimmers are heading up to Auckland too early. Many are forgetting we've got EIT here and if they stay here an extra year they will be stronger when they leave."
Prior to McLay's arrival in the Bay the Sundevils were on the verge of going into recess. McLay has helped get the club back to being a competitive force on the national scene. But it still has a long way to go before the glory days - when Olympian Jon Winter was head coach from 1998-2007 - are repeated.
"It was good to see the club become a force again. We travelled back from every age group meet we went to with medals. Watching youngsters in the club grow as swimmers was a huge highlight for me," McLay said.
McLay, the husband of Napier Aquahawks coach Anna McLay, said it was an emotional experience saying goodbye to his squad members. He singled out Jim Missen, Emma Godwin, Emily Roberts, Alex Schroder and Tuhono Matairangi as "just some" of the Sundevils with potential to make an impact at national level.
McLay's former assistant, Olympian Willy Benson, will replace him as head coach.