I've owned this boat for ~12 years. Since I purchased it from the original owner, I've always winterized it the same way he told me he did.
The engine is a Ford 302 H.O. FI. It has a drain on each side of the engine block with two hoses that "Y" together to a third hose which has a threaded on cap and clips up next to the oil dip stick.
Skipping the other steps....
With the engine up to operating temp running on the ear muffs, I shut it down, remove the cap from the drain hose and let the water drain. I then fire it up again on the ear muffs, but this time running on a hose attached to a big jug that I fill with a couple gallons of ethylene glycol. Run the engine until all of the antifreeze runs out of the jug and shut it down. Then drain the antifreeze from the block using the drain hose mentioned above.
This is what I have always done to make sure there is some antifreeze in the engine and not water to prevent freezing. A friend of mine who has a similar setup told me it is not necessary to run any antifreeze through the engine and that simply draining the water from the block via the drain hose setup is sufficient for winterizing.
Since the boat has always been winterized with antifreeze and worked fine each spring, I highly doubt that I would ever change my process. BUT, is my friends way actually acceptable? I would think that you still have water in hoses, passages, risers, etc which could stick around even after using the block drain and possibly cause an issue. I am incorrect? will water work its way out on its own and drain out of the block drains and be ok???