After two years of improvements I finally think I have arrived at the (almost) ultimate winter fun plane. (I say "almost" because no one has invented a “Good Weather” button yet)
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I started out with Datum wheel skis and soon found out there was more to winter flying than just adding skis if one wants to fly in -20 degrees Celsius weather.
There is cabin heat – not much, but it became bearable after I replaced the snap vents with solid discs of Lexan and sealed all the draft holes around the doors and cowling..
Starting the Rotax 912S was challenging in cold weather. By the way, the engine is equipped with the soft start module. I tried a heat gun first, but the rickety arrangement was less than ideal. I ended up installing a Reiff pre-heat system. It draws less than 300 watts and takes from one to four hours to pre-heat. If I plan to fly early in the day, I plug it in the night before. On outings with longer stop-overs I’ll take my small Honda 350 generator along to keep the engine warm.
In the hangar the cowling is covered with a blanket of bubble insulation held in place by my regular cowling cover. I also keep a small battery minder connected, to ensure the battery is always fully charged.
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The oil temperature stayed within range after I covered about half the rad with aluminum tape.
One of the challenges was to keep the coolant within the proper temperature range. I had lowered the rad by one inch to get more cooling air when taxiing on floats. The additional exposure kept the coolant temperature too low in cold weather. I built a new air duct with a cockpit adjustable exit baffle. It is now easy to keep within the proper temperature range and to bring the temperature up quicker on startup. The air duct is constructed in two parts to make removal quick for the changeover to floats.
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I am sure, if I try hard enough, there are other improvements to be found – perhaps someone out there can point them out.

In the meantime, it is great fun to go flying even when it is very cold – the whole world is my runway!

Ron