Boats are fun in the summer and vulnerable during the winter-season. Summer is the time for riding the tide and splashing the waves; winter is your turn for returning the favor and give your boat some care and love, so for it to survive and remain intact for the next season!
Summer is almost synonymous with water. The opposite is true for the winter, as far as your vessel is concerned. Your boat wants to stay out and away from the water during the winter. It really prefers being tucked under cover and situated in a climate-controlled boat-storage area. But that's a big generalization and very non-specific.
While we've cut through the clutter and put together this guide, which contains all the important as well as the basic odds and ends for boat storage, the best place to start off with is the manuals of your boat and motor, which should be providing you with some helpful to-do pointers and markers. The subsequent paragraphs serve as a good, logical pattern to follow, and as always, if you're not sure don't hesitate to reach out to a friend with the proper expertise.
Run the engine and change the oil once the engine has warmed up. Change the oil-filters and flush the engines with fresh water. Flush the engine with antifreeze; use a pickup hose from the water-pump to a bucket of antifreeze, and run the engine to allow for the antifreeze to circulate.
Next, change the fluid from the transmission. Remove spark plugs and use "fogging oil" to spray into each cylinder. Wipe down the engine with a shop towel sprayed with WD-40 or a little fogging oil.
Flush the engine with fresh water using flush muffs, and allow for the water to drain from the engine. Wash the engine with soap and water and then rinse it completely.
Carefully inspect the stern drive and be sure to remove all signs of plant life and barnacles from the lower unit. Drain the gear case and check for moisture in the oil, which could denote leaking seals. Clean the lower unit with soap and water, and Grease all fittings and check fluid levels in hydraulic steering or lift pumps. If your stern drive has a rubber boot, make sure it doesn't have cracks or pinholes.
This is one area where you should be following the manufacturer's recommendations, as the suggestions of how to be dealing with fuel aspect is different for different manufacturers. some recommend filling up the fuel tank and adding a stabilizer, while others suggest adding just the stabilizer while leaving the tank empty of fuel.
Use fogging oil in the cylinders to lubricate the cylinder walls and pistons. Apply water resistant grease to propeller shaft and threads. Change the gear oil in the lower unit. Lightly lubricate the exterior of the engine or polish with a good wax.
After disconnecting and removing the batteries from the boat, clean the terminal-ends and battery with baking soda and water, and rinse thoroughly with clean water. Put a light coat of grease on the terminal end of both, battery and cables, and store them in a dry place.
After making sure the bilges are clean and dry, you'll want to ascertain that they're free from possible oil-spills. Do that using soap, warm water, and a rigid brush. Once done, spray some moisture displacing lubricant and add a little antifreeze to prevent any water from freezing.
Fresh Water System
Drain and completely empty the hot-water heater and fresh-water tank. Be sure to isolate the heater disconnecting the in-and-out lines and then connecting them together. Get some non-toxic antifreeze into it and then turn on all facets on your boat. Let them run till the antifreeze comes running out.
Pump out the holding tank, and add during pumping some fresh water to the bowl flushing several times. Insert Vanish Crystals (consult the manual to make sure that your system can take it without being damaged.) and leave it there for a few minutes, and add water and pump out again. Add antifreeze and pump through hoses, holding tank, y-valve, macerator and discharge hose. Consult the manual to make sure that your system can take an alcohol-based antifreeze.
Once done with all the steps listed, remove all electronics, lines, flares, fenders etc. Check and where necessary clean the drawers and lockers, and, if you're planning on leaving them on the boat for the winter, get the cushions up on their edges, so for the air to be able to circulate and get everywhere. A good idea is to install a dehumidifier or some form of odor and moisture absorber product.
Pressure the wash hull, clean the barnacles off props and shafts, rudders, struts and trim tabs. Clean all thru-hulls and strainers. Open seacocks to allow any water to drain. Check the hull for blisters and open them to let them drain during the winter.
Close all seacocks and check rudder shafts and stuffing boxes for leaks, tighten or repack as necessary. Make sure the battery is fully charged, clean terminals, add water if necessary. Check the bilge and make sure that float switches properly activate the pumps. Make sure either to check your boat periodically or have the marina check it and report to you. If in an area where the water you are docked or moored in actually freezes, you should have a de-icing device or bubbling system around your boat.
Following these suggestions will do your boat good in having it survive the winter and remain intact for the following boating season. Keep in mind, though, that these are merely pointers and should be taken as such. Consult your owner's manual and follow the listed guidelines and instructions.