but totally doable.

First all tanks must be drained of course - holding, fresh water, and hot water heater etc. Don't forget all pumps and lines must be pumped clear or blown out as well ( in a perfect world all fresh water lines would gravitate to a low drain point in the bilge - four or five lbs of air pressure injected into an upper fitting would then clear everything at once) since boat systems are seldom perfect however, each sub-system will have to be checked and verified individually. Drinking water filters are especially vulnerable and should have the element removed for the winter as some of them are near impossible to drain properly. Bilge pumps and lines must be cleared of any standing water as well.

As we move along to the engine, you will want to check the anti-freeze dilution in the freshwater cooling system and verify it capable of handling any expected low temps for your area. The raw water side of the cooling system is best winterized by introducing an additional mixture of anti-freeze from the raw water inlet, through the water strainer, the raw water pump, up through the heat exchanger and INTO THE EXHAUST SYSTEM - contrary to popular thought, the water lift muffler can freeze solid enough to craaaack. This is why anti-freeze is a better solution (and easier) than trying to drain the raw water side which can be difficult to evacuate completely.

Many people seem to think it necessary to remove the batteries for the winter - I don't - the battery in your car, tractor, truck, motorcycle, stays outside all winter without incurring any undue harm - why should a boat battery be different. I do recommend a trickle charger be left on the system should that be available to you.

Living in Colorado, and winterizing all sorts of vehicles each year has taught me not to skimp on this seasonal chore.