Winterizing a boat: a checklist you can run step by step

Winterizing is a long list of small jobs, each cheap to do and expensive to forget. The list below is arranged by system in the order the work usually goes, so that the engine is run before the fuel is treated and the water is drained before the antifreeze goes in. Products, quantities and the exact steps for your engine come from its manual; the list says what to do, the manual says how.

Before you start

• Make the shopping list: oil and filters for every engine, the fuel treatment for your fuel, non-toxic antifreeze for the freshwater and raw-water systems, fogging oil, gear lube, a fresh impeller if one is due, zincs, and the gaskets and O-rings the filters need.
• Check what is already aboard before you buy. The lockers usually hold half the list from last year.
• Record the hours on every meter. Winterizing is a service, and the schedule needs the hours it was done at.
• Keep the winter storage page from each engine and generator manual within reach. It is a page or two, not the whole book, and it settles the few things that differ by model: the oil grade and quantity, the route the antifreeze takes, and whether the maker wants the cylinders fogged.

Engines and generator

• Run each engine to operating temperature, then change the oil and filter while it is warm. Used oil holds acids that sit in the engine all winter if it is left.
• Change the fuel filters and the water separator elements.
• Check the coolant strength and top up or replace as the manual says.
• Flush the raw-water side with fresh water, then run non-toxic antifreeze through it until it shows at the exhaust, following the manual's method for your engine.
• Fog the cylinders if the manual calls for it, and close the seacocks.
• Inspect belts, hoses and clamps while the engine room is open; replace what is cracked or soft.
• Give the generator the same treatment on its own list. It has its own oil, filters, impeller and raw-water loop.

Fuel system

• Fill the tanks to reduce condensation over the winter.
• Gasoline: add stabilizer at the rate the product gives for the volume aboard, then run the engines long enough to carry treated fuel through the lines and carburetors or injectors.
• Diesel: add a biocide at the product's rate to stop growth in the tanks over the winter. No run afterwards is needed.
• Note the fuel on board in the log; it is the first question next spring.

Water systems

• Drain the freshwater tanks, the water heater and the lines, then run non-toxic antifreeze through every tap, shower and washdown until it shows pink.
• Bypass the water heater if the manual provides for it, so it does not take gallons of antifreeze.
• Pump the holding tank, flush it, and winterize the head with antifreeze through the bowl and the intake.
• Winterize the watermaker exactly as its manual says; membranes are the most expensive thing on the boat to get wrong.
• Air conditioning and refrigeration raw-water loops: flush, antifreeze, strainers cleaned.
• Bilge pumps: test, clean the strainers, and leave the bilge dry.

Batteries and electrical

• Charge every bank fully. Decide whether the batteries stay aboard on a maintainer or come home, and label the cables if they come out.
• Shut down everything that draws when the boat is unattended, except the bilge pumps and whatever the maintainer needs.
• Clean and coat terminals; check the electrolyte on flooded batteries.

Drivetrain and below the waterline

• Outdrive or saildrive: change the gear lube and check it for water, grease the fittings, inspect the bellows, replace the zincs.
• Shafts: check the packing or seal, the cutless bearing play and the propeller for damage.
• If the boat is hauled, look the bottom over once the yard has washed it, and note the condition of the paint, the zincs and the running gear for the spring list.

Tender and outboard

• The outboard gets its own list: gear lube, fuel treated or run dry as the manual says, fogging, impeller if due, zincs, flushed and stored upright.
• Deflate or cover the tender, and store it where sun and water cannot reach it.

Deck and interior

• Canvas and cushions off and dry; sails off if a sailboat. Hatches cracked for ventilation with a cover that sheds water.
• Food and liquids off the boat, lockers propped open, a moisture absorber in each cabin.
• Flares, fire extinguishers and the life raft: check the dates now so the spring list carries what expires over the winter.
• Close every seacock not needed by a bilge pump, and write down which ones are closed.

The paperwork

The last job is the one that makes next spring easy. Record what was done, when, at what hours, and what was used, against each piece of equipment. Set the spring commissioning reminder now. Put the spares you did not use back on the inventory. Next March, the shopping list writes itself.

This list is general. Nothing here replaces the manufacturer's manuals, intervals or procedures for your equipment; take every product, quantity and step from the manual for your model.