Mr Walmisley said Paddle Wanaka, Lakeland Adventures and Eco Wanaka ''were all up there''. Two of them had boats on the scene so responded quickly.
He said Paddle Wanaka was crewed by a coastguard member, ''but because the [victim] went straight down, regrettably no matter how much searching of the surface we did, it was not going to find him''.
The body of David Barry Fisher (26), of Tauranga, was recovered from the lake by the police national dive squad on Saturday afternoon.
The water depth where the man drowned was believed to have been 13m to 15m.
He was found not far from where he swam out to retrieve a boat that had drifted away near Stevensons Island.
Mr Walmisley said the Wanaka Coastguard rescue vessel with a crew of three was on the water for five hours carrying out full searches of the surface many times.
''We carried out all the normal procedures and I don't think we could have done anything better.
''Had he been floating we would have found him,'' he said.
Mr Walmisley said the message to boat users following the event was ''if your boat happens to drift away please don't swim after it because in any wind the boat is going to drift faster than you can swim''.
The Wanaka Coastguard vessel is housed at the A&P showgrounds. The organisation is hoping to be granted a lease for a new boat shed and rescue centre at Eely Point to provide easier access for the crew and a quicker launch time.
Mr Walmisley said the new boat shed would have made no difference to the outcome of this event.
However, he said the amount of time it could take for the crew to get to the present boatshed and on to the launch site remained an ongoing concern.
He said on Saturday Wanaka Coastguard transported the dive squad back to the scene near Stevensons Island and it took 30 to 40 minutes for the crew to get from the A&P showgrounds to the launch site because of because of heavy traffic along Ardmore and Brownston Sts.
''Unfortunately, we don't have blue flashing lights so we can't barge our way through the traffic, and as most of our members come from the east side of Wanaka they have to cross the traffic and then take the boat back across the traffic to the launch site.''
''It really reinforces, in my mind, the need to have a building on the east side of Roys Bay,'' he said.
