SEASONAL BOAT CARE • SONARK MARINE

Boat Winterizing Checklist

Prepare your boat before freezing weather. Start with your exact engine manual, then build a shopping list for your cooling system, fuel, batteries and onboard water systems.

See winterizing supplies

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Start with your boat and engine

This is a planning checklist. Cooling-system draining, antifreeze application, fuel treatment and fogging methods vary by engine. Follow the manufacturer’s manual for your exact model. If you cannot confirm the required procedure, use a qualified marine technician before freezing weather.

Outboard

Check the manufacturer’s flushing and draining instructions. Mercury advises storing its outboards upright so water can drain. Do not assume an inboard antifreeze kit is appropriate for your outboard.

Inboard or sterndrive

Identify raw-water and closed-cooling circuits. Locate every required drain and follow the engine’s specified winterization procedure. A supply kit does not remove the need to drain or inspect the system as directed.

Freshwater and sanitation

Tanks, pumps, plumbing and toilets need their own winterization procedure. Use products approved for that system. Never put automotive antifreeze in potable-water plumbing.

Your pre-freeze checklist

  1. Gather the manual and record the model. Identify service items, drain locations, required fluids and storage instructions.
  2. Service fuel and engine fluids. Follow the manual’s storage instructions and the treatment label for your fuel type. Use only the fogging or internal-corrosion method approved for your engine.
  3. Protect the cooling system. Complete the specified flushing, draining and freeze-protection procedure. Confirm antifreeze chemistry and concentration with the engine manufacturer.
  4. Winterize onboard water systems. Follow separate procedures for potable water, sanitation, washdown, livewells and other water-holding equipment.
  5. Care for batteries and electronics. Follow battery-maker storage guidance. Choose a charger compatible with battery chemistry and capacity.
  6. Clean, dry and cover. Remove damp gear, inspect drainage and ventilation, and secure the cover for your storage conditions.
  7. Make a spring-start record. Note what was disconnected, drained, treated or removed so recommissioning follows the manual.

Build a winterizing shopping list

These are separate items to consider, not a packaged bundle. Buy only what your boat’s instructions require.

Camco DIY boat winterizing kit

Camco 65501 DIY kit

A gravity-flow antifreeze supply kit for compatible inboard/outboard applications. Check the exact engine connection and Camco instructions. Antifreeze and any required flusher are separate.

Check Camco 65501 on Amazon

Fuel storage treatment

Choose a storage stabilizer approved for your gasoline or diesel system. Follow its dosing instructions and your engine manual.

Find fuel storage treatment

Correct antifreeze

Engine cooling systems and potable-water plumbing have different requirements. Match the product, concentration and application to the system manufacturer’s instructions.

Compare winterizing antifreeze

Compatible flusher

Check your engine’s intake and flushing connection before selecting equipment. A generic attachment may not fit your engine.

Find a model-compatible flusher

Battery storage charger

Match the charger to battery voltage, chemistry and capacity. Follow charging and storage guidance from the battery manufacturer.

Compare battery maintenance chargers

The Camco link opens a specific product listing. The other buttons open Amazon searches so you can match supplies to your boat. Verify included parts and seller details before buying.

Keep the spring safety check on your list

Before launching again, inspect and test safety equipment as directed by its manufacturer, review beacon registration and service dates, and refresh your radio call procedures.

EPIRB vs PLB guide →   Handheld VHF picks →

Manufacturer references

Mercury: winterizing your outboard
Mercury: MerCruiser sterndrive winterization
Camco: confirm current kit instructions

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