Hi,

Somewhere in the back of my head a voice keeps telling me that the maximum allowed amount of fuel in a tank when bunkering is 85% of volume.

I know that this is rarely respected and i cannot find a regulation that explicitly states this. I sail on the canadian west coast.

Does anybody know of Canadian regulations that can confirm or deny my assumptions?

I don't think that's a regulation.
A good practice, for most situation, but I can't see it being a reg.