There is now an audio on the news, so we know that the Beaver was told by the tower to watch for a West bound boat, just before takeoff.
According to that audio, the track of the boat was Westbound and the Beaver was taking off to the Northwest. Visibility between the two was hampered, for the Beaver, by the big Radial engine up front, for the boat, by the angle, with the plane being behind the helmsperson's shoulder. The boat engine noise would have cancelled out the noise of the Beaver.
The boat was "stand on" but if neither was aware of the other before the collision, that counts for nothing.
There is a 5 knot speed zone there too, inside a line from Brockton point to the Burnaby Shoal marker, the speed zone includes the Seaplane Landing area, but of course the seaplanes land and take off at considerably higher speeds. And no, that speed zone is not observed by many, only west of the Seaplane landing area does the wash from boats exceeding 5 knots matter, so only there have I heard of any enforcement whatsoever of the speed limit. Heck, even the VRC racing shells go faster in their practice lanes.
From the video, the boat looks to be exceeding 5 knots, though I doubt that would have made a difference.
In the latest news report on Global, a similar collision about 25 years before resulted in a "Neither party to blame" TSB conclusion.
2 passengers on the boat were hospitalized, all on the plane escaped unhurt.
I have flown HA Beavers in Coal Harbour many times, including sitting in the rt front. Never saw any indication of a VHF Radio. During takeoff the pilot is on the tower frequency. If the pilot didn't see the boat before starting takeoff, visibility would only get worse as the plane accelerated, with the radial engine obscuring more and more of what was directly in front.
That "Seaplane Landing" area shown on the chart above, is also a Cruise Ship backing zone and the only way to go east from Coal Harbour in a pleasure craft moored west of the Seaplane dock, so a very busy place.
The last time I flew in, at 6:15 PM April 30, 2024, there were 2 cruise ships and some pleasure craft in that area and the Harbour Air Otter had to land in the farthest west corner of that area. Of course getting a bird's eye view while landing is far better than the view this pilot would have had while taking off.