Modifty an outboard motor to power an "Iceboat"?

This may sound insane, but back in about 1969 or 70 I rode in an aluminum boat over a frozen lake, powered by an outboard motor whose "prop" was a large toothed disk (much like a circular sawblade, only larger) that dug into
the ice to push the boat along. Naturally, the disk turned perpendicular to a normal outboard propeller. Steering was just with a standard tiller arm.
This thing worked amazingly and was very very fast !

My question is this.... Can someone explain how an outboard can be modified in this way?

 

Icefisher,
It may not be workable to modify an outboard for this purpose, but making an arrangement with a general purpose engine should be easier in my opinion. This sketch is just to throw an idea.

 

How did they cool the engine ? Most outboards require liquid water .

FF

 

I wish I knew!.. I was 11 years old at the time and never thought to ask the
owner of the ice shanty rental place.

Ive run across info about a company called Polar Motors that actually made
an outboard exactly as described in my first posting. It was only sold for 1
year (1964) so it may have been one of those and not a modified motor at
all. The outboard didnt sell very well so Polar quit making them and switched
to snow machines and changed their name to Polaris.

Still, I thought there were/are air-cooled outboards that might be modified.
Anyone out there.. Are there air-cooled outboards around???

 

I can imagine it will be great fun with safety, when you get the required machine.