Heading (cheerfully?) into our fourth Toronto Harbour winter on our Niagara 35Mk1. We have two 30A shore power feeds to power three oil circulating electric heaters for us, and one fan-forced heater for the engine. There are two 3/4hp "Ice Eaters" under the boat. They typically run continuously from mid Dec 'till early March.
The engine and cockpit lockers are kept at 10C all winter. There's a magnetic block heater sticking to the Volvo MD11C engine to aid in winter starting.
We do not winterize the boat at all. There is a semi-clear shrink wrap cover over the whole boat to produce a lovely greenhouse effect on sunny winter days.
For more details read our Winter Liveaboard blog