Well it's been 12º F for the past three nights at my place just S. of Lynnwood.
On my 3JH I have put in a Tee above the seacock where I plumb in a hose from a bucket. For winterizing I flush the motor
with fresh water until it reaches temp then add add antifreeze
to the bucket. When the bucket empties I shut the motor
Next I close the seacock, drain the wetlift and pull the impeller from the raw water pump
. I spray the impeller with silicone and put it and the coverparts in a baggie.
Then I spray the whole motor down with WD-40 or if I'm on the hard
I keep a 250 watt lamp in the motor compartment to keep the motor dry.
But the boat's in SF now so it's just flushed with fresh water.
And don't forget about any other water pumps on the boat they will freeze too. I had to repair my deck
washdown pump one year due to forgetfulness.