How often to clean your hull in California

Cleaning schedule by paint type

A 2019 guide from the Port of San Diego, Los Angeles County Beaches and Harbors, the state Division of Boating and Waterways and the Coastal Commission sets out three kinds of bottom paint and how often to clean each.^[1] Frequency and method still vary by product and by local water, so the paint label comes first.

*Paint life figures are manufacturers' claims, as reported in the guide.^[1]

The same guide notes that paint makers recommend copper paints not be cleaned if the boat is used frequently, and that a boat sitting for six months or more is "inactive", which changes the best choice of paint.^[1] The Coastal Commission's factsheet adds that a slime layer on a biocide paint may not need cleaning at all: clean when an inspection shows real fouling, and target the denser growth.^[2]

Not sure what's on your bottom? Your last haul-out invoice usually names the paint. If not, ask the yard that did the job before you set a cleaning schedule.

Guidance, paint labels and local requirements

Three different things set how often a hull gets cleaned. Keep them apart:

• State guidance. The 90-day wait and the 30-day copper spacing come from the 2019 state hull-paint guide and the Coastal Commission's hull cleaning factsheet. They are recommendations for boaters and divers, not a state law.^[1][2]
• The paint maker's label. The label and data sheet for the product on your boat say when it can first be cleaned and how. Follow it where it differs.
• Local requirements. Some harbors turn the guidance into their own rules. Long Beach's marina policies say not to clean a hull for 90 days after paint is applied.^[4][5] Sacramento Marina's BMPs and Berkeley Marina's berth rules say to wait 90 days after new bottom paint.^[6][7] San Diego Bay requires a Port permit for every hull cleaning business,^[3] and Marina del Rey requires BMP-certified hull cleaners.^[8] Where a harbor sets a rule, it's that harbor's requirement; check yours on its harbor page.

Why copper paint gets special treatment

Copper paint works by leaching copper into the water, and copper hull paint is the largest source of copper pollution in California marinas.^[1] When a soft (ablative) copper paint is cleaned, some paint comes off with the growth. Clean too hard, or clean paint that isn't well bonded, and flakes of active copper go into the water.^[2] Gentle, infrequent cleaning keeps the paint (and its copper) on the hull, where it keeps working.

Since June 30, 2020, copper paints that leach more than 9.5 µg/cm² per day can't be sold for recreational boats in California.^[1] Last verified November 11, 2026

The three copper-impaired harbors

Three Southern California marina areas are listed as impaired by copper, with cleanup plans (TMDLs) run by the Regional Water Quality Control Boards:^[1]

• Shelter Island Yacht Basin, San Diego (San Diego Region 9)
• Marina del Rey (Los Angeles Region 4)
• Newport Bay (Santa Ana Region 8)

In San Diego Bay, every hull cleaning business needs a bay-wide Port permit ($250) and must use best management practices on any boat it cleans. The Port says it is reviewing and updating its in-water hull cleaning policies; it temporarily paused in-water cleaning in Shelter Island Yacht Basin from December 19, 2021 to February 9, 2022.^[3] Last verified November 11, 2026

What a good cleaning looks like

The Coastal Commission's hull cleaning practices, drawn from the California Professional Divers Association's manual, are a good checklist for any diver:^[2]

• Inspect first; clean only when the growth needs it.
• Clean by hand with cloth, plastic scrapers or soft scrubbers. No power brushes.
• Use the least abrasive method that works, and never wet sandpaper.
• No visible plume of bottom paint in the water.
• If the growth needs metal scrapers, the boat should be hauled out and cleaned where paint and debris can be captured.
• No cleaning on newly painted hulls for at least 90 days (the guidance's wait).
• Report chips, flaking or cracks in the paint to the owner.

Ask your diver to check the zincs on each visit. Zincs that suddenly wear much faster than usual can be a warning of stray current in the boat or the marina.^[9] More in zincs, haul-outs and bottom paint.

What this means for cost

Your paint sets how many cleanings you pay for in a year. That arithmetic, from the intervals above:

• Copper: at most about 12 cleanings a year if you follow the guidance (no more than one every 30 days), and fewer if you only clean when it's needed.
• Non-copper biocide: every 3–4 weeks is roughly 13 to 17 cleanings a year.
• Non-biocide: every 2–4 weeks is roughly 13 to 26 cleanings a year.

Yearly cleaning cost is the price per visit times the number of visits. Non-biocide coatings need more cleanings, but they last longer and can be recoated without stripping the hull, so they may cost less over time. Switching from copper usually means stripping the old paint first, which raises the upfront cost.^[2]

When you compare quotes, ask:

• Is the price per foot of length overall or of waterline?
• Are zincs, and the labor to change them, included or extra?
• Is the running gear (prop, shaft, struts, trim tabs) included?
• Will you send photos or video after each cleaning?

For published prices, see the hull cleaning cost guide. To work out your next cleaning date from your paint and paint date, use the hull cleaning interval estimator, and send any diver the same facts with the service request brief.