How to Clean a Boat Hull

July 25, 2022

Cleaning a boat hull is a necessary task that often goes overlooked. Over time, boats get dirty and weathered, so it’s important to regularly clean their hulls to remove any buildup of scale, rust, algae or salts.

Join the experts at the National Boating Safety School as they explain when and how to clean your boat’s hull.

 

Boat hull cleaning is an important part of boat maintenance

The hull is the part of a boat most exposed to the various elements. Over time, it can become covered with dirt, scum and other effects of weathering. The gelcoat that covers the hull can also turn yellow from exposure to ultraviolet light.

It’s always a good idea to maintain your boat’s hull by regularly cleaning it with the right products. It’s also important to use the right methods.

 

How often should I clean my boat hull?

To keep your boat in top working condition for as long as possible, it is recommended that you clean your boat hull several times a year, depending on how often you use it and the types of marine environment you visit.

Depending on whether you use your boat in a freshwater or saltwater body of water, you’ll need to clean your hull every 4 to 12 weeks to prevent excessive buildup of grime and growth. Rinsing the hull after each trip and a doing a light annual polishing job are also recommended.

 

Cleaning a boat hull explained

  1. Haul your boat onto land so you can wash it with fresh water. This is important for your boat, because it allows you to dry it completely, and access the entire surface. It’s also important to prevent cleaning chemicals from entering local ecosystems and causing pollution. Check for marinas in your area that provide designated cleaning areas, or, if doable, you can clean your boat at home in your own driveway.
  2. Remove any debris, and inspect the hull for any obvious damage. Remember, your boat hull has been designed to withstand a lot of wear, so don’t worry about surface scratches or other marks that pose no threat to the structure or permeability of your boat. Just make sure the damage is not likely to cause a leak. IF you find a problem, now it the time to repair your hull.
  3. Choose an appropriate cleaner, keeping in mind that you don’t want to accidentally clean off your Hull Identification Number or any other important markings.
  4. Get a bucket of fresh water and use a low-powered water jet to rinse the entire hull. Be sure to remove any mold, salt stains, loose dirt, brown slime and algae that have clung to the hull. You can also use a soft brush or cloth, which prevents scratching during the cleaning process.
  5. Soak a large, soft sponge in a hull cleaning solution and wring it out lightly, then scrub the hull down to the waterline.
  6. Clean from top to bottom, and from bow to stern, and be careful not to damage the paint.
  7. When you’re finished, gently rinse the hull with a low-powered stream of water, then pass a second sponge soaked in clean water over the hull to wipe off any residual stains and cleaner.
  8. Let your hull dry completely before doing a final seal or wax job.

8 tips for cleaning a boat hull

Here are some recommendations from our experts to thoroughly clean your boat’s hull without damaging it:

  1. A boat hull cleaner and fresh water are more than enough for a complete cleaning.
  2. Buy a cleaner made for boat hulls and dilute the labeled amount in a bucket of water.
  3. Avoid cleaning your boat’s hull in the sun, as the water and cleaner may dry quickly. If this is not possible, do the job in small patches.
  4. Be cautious with soft antifoul paints as they may come off more easily.
  5. Use a biodegradable limescale remover for topsides and apply it in sections. Let it sit briefly before scrubbing with a sponge in circular motions.
  6. Rinse off all cleaning agents with fresh water to ensure no residue remains that could harm marine life or affect the hull’s finish.
  7. Apply a UV-resistant wax to protect against sun damage and help prevent future growth of algae and other marine life. Buff it out for a shiny finish.
  8. Remember, there are different types of hulls, and some may be easier to maintain than others, or require different methods.

If you own a motorboat, we also invite you to read about how to clean a boat fuel tank.

 

How to clean yellow stains off a boat hull

After a few years of use, even the shiniest boat hulls can stain yellow. The gelcoat that covers the hull will discolour from exposure to ultraviolet light or become dull from oxidation.

To restore the shine to your hull, first clean the surface as described above. Once the boat hull is clean, the yellow stain can be removed by using oxalic acid (sorrel salt) diluted in a bucket of clear water. It is recommended to put on protective glasses, gloves and clothing before handling this solution. Wipe the yellow stained areas with a cloth soaked in the solution and immediately rinse the area with a low-powered stream of water.

 

Learn more about boat hull maintenance with the National Boat Safety School

Overall, hull cleaning is an important part of keeping your boat performing at its best. By following the advice of our experts, you can maintain your boat’s hull without worry.

If you’re interested in learning more about what it takes to maintain a vessel or obtain a boating license, the National Safe Boating Institute is your best bet.

Enjoy our Transport Canada approved boat safety course and get ready to take the boating exam so you can legally navigate Canadian waters.

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