CUTC was the Canadian Underwater Training Centre which was the only North Sea rated school in North America at the time. It was based on an old tanker named the Fuel Marketer in Toronto Harbour and also had a 70' dive tender called the Lois T.
They used to dive the harbour over the side or through a moon pool in the bottom of the ship if the ice got too thick. The harbour was used for the basic skills. but once that was over, virtually everything was done at 165' out in the lake off the Lois T. They had several moorings (class rooms) out in the lake but I don't think any were shallower than 160.
It was a very busy school in it's day as graduates from all the other North American Schools had to pass through there if they wanted to upgrade to a North Sea rating. They did mostly standard air, chamber operations etc. but got into mixed gas when the Dept. of Labour set the max air depthg at 165.
All the instructors were retired military, ex DCIEM types and when the the city didn't want to renew the leace (lets clean up the harbour front days) they decided it was time to retire for real.
The Fuel Marketer was sold for scrap. The large chamber was donated to Seneca Collage and the Lois T with small chamber was sold to Nadro Marine. It has since been sold again and renamed the Charlie E and sits in Port Colborne Harbor.
Craig Workman of Lake Erie Marine Services leases it for dive charters when he has enough people interested.
In any event, I don't think the block was a CUTC mooring. Both the Sligo and Morell have big blocks on them 2'x4'x8' which I helped put there many years ago. I haven't been there for years, but I was told that the Sligo has a SOS type buoy on it. I don't know about the Morell.