G'day Jack,
Also, the Victa Jet outboards ran this mix. This was BP Outboard.
BP Zoom Outboard, actually.
As far as I can recall, the Victa Jet outboard ran 'BP Zoom 25', same as the rotary mowers. We ran one of these on a 10' aluminium punt for a while in the 70s, and I don't recall having to mix special fuel for it.
Noisy bloody thing with the standard Victa muffler, it was. A straight-through stainless steel [90 deg bend + milking machine milk line tubing] underwater outlet exhaust pipe quieted it a lot.
The bulk BP Zoom 25 drum in my family's OPE shop supplied the fuel for our Victas, tho' we did mix up some 20:1 fuel, using Castrol Super Outboard 2-stroke oil [as that was what Mobilco specified], for our Mobilco Echo saws.