How To Easily Remove Stains From Boat Hull

Paul Stockdale Author Avatar
Written by Paul Stockdale | February 16, 2023
Boat hull stain removal

Removing stains from the boat hull will improve the overall aesthetics of the vessel.

There can be a build-up of waterline stains, rust stains, brown stains, oxidation stains, yellow stains and tannin stains, especially on fiberglass boat hulls with a gelcoat finish.

What's the best way to remove these stains from the boat hull?

To remove stains from the boat hull:

  1. Place the boat on a trailer or lift
  2. Use a pressure washer to remove excess dirt & salt water
  3. Scrub the boat hull with a brush, warm water and hull stain remover cleaner & rinse it with a pressure washer
  4. Dry the hull with towels to remove final stubborn stains
  5. Apply a boat polish to the hull to add a shine

Applying these steps will remove even the toughest of stains from the hull.

These steps of removing stains apply to boats that are out of the water rather than boats that are in the water.

Step 1: Place The Boat On A Lift Or Trailer

The first step in removing stains from the hull is to take the vessel out of the seawater.

To take the boat out of the water:

  • Move the boat to near the boat ramp: Move your boat up to the boat ramp and get it ready to take out of the seawater
  • Back the boat towing trailer into the water: Back the towing trailer into the water so it's easy to move the boat onto the ramp
  • Move the boat onto the trailer and drive it off the ramp: Use a rope to pull the vessel onto the trailer or simply drive it onto the trailer

Once the boat is out of the water and on the towing trailer, you're ready to remove those stains around the hull area.

Taking the boat out of the water first will:

  • Make it easier to remove stains: The boat taken out of the water makes it easier to identify and remove hard stains
  • Ensure a thorough clean and no missed stains: With the boat out of the water, you can clean stains from spots not reachable when the vessel is in the water and ensure you don't miss stains that may have been difficult to identify if the boat remained in the water
  • Help remove stains faster: With the boat out of the water, you can apply cleaning agents that will dissolve stains much faster than manually trying to scrub them out when the boat is in the seawater

If you do not have a boat trailer, a boat lift can be used. This is more common for much larger boats.

Take the boat out of the seawater. This will make it much easier to remove all stains from the hull and apply the boat polish.

Step 2: Use A Pressure Washer To Remove Excess Dirt

The second step in removing stains from the boat hull is to use a pressure washer to remove the excess dirt and easier stains from the hull.

Simply power wash the hull surface with warm water and marine-grade soap to get the boat hull prepped in the next step.

Using a power washer on the boat hull will:

  • Remove the loose dirt and easier-to-remove stains from the hull first: A pressure washer will blast away the easier and loose dirt first before tackling the deeper stains
  • Remove salt deposits from the hull: The pressure washer will remove the salt deposits on the hull
  • Prepare the hull for a stain remover cleaning product and boat polish: Using a pressure washer will blast away all salt deposits and heavy dirt. This will make the marine hull stain remover and boat polish more effective when applied to the hull

Boat owners will need to use the pressure washer in preparation for stain removal.

Boat owners will need to use the pressure washer to remove any excess dirt. This is important to help prepare the boat hull for removing stains

Step 3: Scrub The Hull With Hull Stain Removal Cleaner & Rinse It With A Pressure Washer

The third step in removing stains from the boat hull is to scrub the hull with a soft bristle brush, warm water, and hull stain remover cleaning product.

To scrub and clean the stained hull:

  • Use a brush and start deeply scrubbing into the stained areas on the hull surface: Deeply scrub the stained areas of the hull with a brush to tackle the stained areas
  • Apply hull stain remover product to the hull stains: Use a hull stain remover product and wipe it onto the stained surfaces on the hull
  • Scrub the stained hull area again with a scrubbing cloth or brush: Scrub the stain remover product into the stained area and let it sit for up to 5 minutes at most
  • Pressure wash the stained area with a power washer: Use a pressure washer to blast away dirt and stains from the stained area of the boat hull.

Using a hull stain removal cleaner and pressure washer to rinse the boat's hull will:

  • Remove all stains from the hull: A specially formulated stain removal cleaning product will help remove those yellow, brown, water and scum line stains from the hull. It is specifically designed for hull stain removal
  • Restore original color: A stain removal cleaner will help restore the hull back to the original color when it was new
  • Add a protective coating: Using a stain removal hull cleaner will help add a protective coating to the hull to reduce new stains from forming
  • Remove the dirty soap and stains: Rinsing the boat hull will help remove dirt and stains.
  • Help spot any missed stains: Rinsing the hull will help you spot any tough stains missed during scrubbing.
Use a brush, warm water, and hull stain removal cleaner to scrub the deep stains in the hull area. Then rinse it off with a pressure washer.

Step 4: Dry The Boat Hull With Towels Or A Cloth

The fourth step in removing stains from the boat's hull is dry the boat hull with a towel or cloth.

Use a towel and rub it in a circular motion around the rinsed hull area.

Drying the hull with a towel or cloth will:

  • Remove the final stubborn stains: Using a towel to dry off the hull will remove the final stubborn stains on the hull area
  • Prepare the hull for polishing: A towel will clear all the final dirt, dust and stains. This will help prepare it for polishing
  • Remove newly formed water stains: Water stains from cleaning will be prevented if a towel is used to dry the hull
Use some old towels to dry off the hull after it's been rinsed. This will help remove any final stubborn stains from the hull.

Step 5: Apply A Boat Polish To The Hull

The fifth step in removing stains from the boat hull is to apply boat polish or wax to the hull surface after it's been dried off.

This is an optional step but it will add a shine to the hull surface and have it looking like new.

Applying boat polish to the hull area will:

  • Add a shine to the hull: Polish will have the hull looking new and add a shine to both aluminum, fiberglass or gelcoat hull surfaces
  • Improve boat aesthetics: Boat polish will improve the overall aesthetics of the boat
  • Add an extra layer of protective coating: Some boat polishes will add an extra layer of protection to the hull against discoloration and help prevent future staining
Polishing the boat hull will add a shine and have the boat look like new. Some boat polishes will also add an extra layer of protection against discoloration and stains.

Products Needed To Remove Stains From A Boat Hull

The products needed to remove stains from a boat hull are:

  • Pressure Washer: This is needed to blast away the toughest stains
  • Stain Removal Hull Cleaner: This cleaning agent is needed to remove all those stains from the hull without damaging the material
  • Bristle Cleaning Brush: This is used to scrub the hull
  • Towels: These are used for drying the hull
  • Boat Polish: This is used to give an added shine and have the hull looking new
  • Bucket: Use a bucket for the scrubbing of the hull with a brush

The best boat hull cleaners for removing stains are Star Brite Instant Hull Cleaner and Better Boat Instant Hull Cleaner.

A pressure washer, boat hull cleaner, towels, boat polish, bucket, towel and a cleaning brush are needed to remove stains from the hull.

Alternative Hull Stain Removal Option

An alternative option for having stains removed from a boat hull is to hire a professional boat cleaning company.

Hiring a professional boat cleaning service will:

  • Ensure all stains are removed: A professional service will have experience removing stains from all types of hulls
  • Ensure the right cleaners are used: Most professional cleaning companies will have all the required cleaning products needed to remove all dirt and stains from a boat hull
  • Remove the stains faster: Most cleaning companies will remove stains and dirt from the hull faster than a first-time DIY project
An alternative option is to hire a professional cleaning company to remove stains from the boat hull. Typically, your local marina will provide contact details for these services.