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Yacht Detailing and Marine Repair in Annapolis, Maryland

Frank Hoot completing a Winterization process: Fluid and filter changes in a couple big CAT Diesels.


Winterizing Checklist

Diversified Marine is your “one-stop” answer to all seasonal yacht needs, including winterization.

Give us a call or email today to schedule your boat winterization project.

Please note: This is a general checklist applicable to most boats. The best source of information about preparing your boat for winter storage is your boat’s Owner’s Manual. Consult manufacturer’s literature supplied with your boat and its components for specific long-term storage recommendations.

Download a printable copy of this checklist.

Engines & Drive Trains

  • Add fuel stabilizer to fuel and run engine for a few minutes to circulate stabilized fuel.
  • Spray fogging oil into intake while engine is running.
  • Top off fuel tanks to reduce condensation.
  • Drain water from inboard and I/O engines and risers.
  • Replace water with engine antifreeze.
  • Drain crankcase oil and replace. Add oil stabilizer.
  • Replace fuel and oil filters.
  • Remove and inspect spark plugs. spray fogging oil into engine cylinders. Turn engine using flywheel.
  • Inspect ignition wires and system components. Replace as necessary.
  • Inspect all hoses for signs of softening, cracking or bulges.
  • Use an engine flusher to remove salt, silt and sediment from engine’s lower unit.
  • Replace lower unit gear lube.
  • Lubricate all grease points: tilt/trim, steering, control cables, etc.
  • Clean and degrease engine.
  • Apply touch-up paint as needed.
  • spray corrosion inhibitor on engine exterior.
  • Remove prop and inspect for damage. Grease prop shaft. Store prop indoors.

Potable Water System

  • Drain water from all freshwater system lines and pumps.
  • Inspect pump impellers for wear and lightly lubricate with Teflon®-based grease.
  • Inspect hoses for signs of softening, cracking, bulging, leaks or pinholes and replace, if necessary, before filling lines.
  • Inspect hose clamps and replace if necessary.
  • Fill all plumbing system lines with nontoxic propylene glycol-based antifreeze.
  • Before recommissioning your vessel, add water freshener / purifier tabs to freshwater tank to remove residual odors and condition newly added water.

Marine Sanitation Systems

  • Empty waste holding tank at an approved pumpout facility.
  • Rinse holding tank thoroughly to remove residual waste.
  • Pump antifreeze through bowl.
  • Lubricate gaskets and seacocks.
  • Check hoses for calcification and signs of wear. Replace damaged hoses if necessary.
  • Wash out vented loops.
  • Fill discharge and intake hoses with antifreeze.
  • Add antifreeze to holding tank to prevent freezing of residual waste.


  • Clean and drain bilge completely.
  • Inspect and lubricate all seacocks.
  • Clean out refrigerator, ice box and freezer. Block door open and leave an open box of baking soda inside to absorb odors.
  • Remove cushions and curtains and store ashore.
  • Check and clean all storage compartments.
  • Secure all hatches and ports.
  • Place an appropriate number of dehumidifying devices or a thermostatically controlled heater in safe area away from combustible materials.
  • Check to make sure all ventilators are operating properly.


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