Hull cleaning interval calculator
A suggested first cleaning date for new bottom paint, a suggested interval after that, and six planning dates, from California's hull-cleaning guidance for your paint type. The state guidance is not a legal rule; your paint maker's label and your harbor's own requirements are shown separately and come first.
Your cleaning plan
Suggested first cleaning (state guidance)
Mon, Nov 30, 2026
19 days to go: state guidance suggests waiting 90 days after new paint.
Suggested interval (state guidance)
Only when needed, no more than once every 30 days
Dates below are 30 days apart (the closest spacing the guidance suggests for copper).
Suggested planning dates
- +30 days
- +30 days
- +30 days
- +30 days
- +30 days
For copper paint these are the earliest suggested dates, not a quota: have the diver check and clean only when growth needs it.
- Ablative paint is designed to wear away, so ask your diver for the least abrasive method that works.
What this is based on
State guidance (not a legal requirement)
- The state hull-paint guide and the Coastal Commission suggest waiting at least 90 days after new bottom paint before the first in-water cleaning.[1][2]
- Copper paint: the guidance suggests cleaning only when needed, and no more often than once every 30 days, and minimizing cleaning of biocide paints so they keep working.[1][2]
- Inspect regularly and clean only when the growth needs it.[2]
- Clean by hand with cloth, plastic scrapers or soft scrubbers; no power brushes or wet sandpaper, and no visible plume of paint. If it needs metal scrapers, haul out instead.[2]
State regulation (paint sales)
- Copper paints with a leach rate over 9.5 µg/cm²/day may not be sold for recreational boats in California after June 30, 2020.[1]
Paint maker's label
- Follow the label and data sheet for the paint on your boat: some set their own wait before the first cleaning and say how to clean it. Your boatyard invoice names the product.
Local requirements
Pick a harbor to see its published rules. Harbors and marinas can set their own requirements (permits, BMPs, a wait after new paint); those apply on top of the guidance above.
The dates above are suggested planning dates from state guidance. The paint label and your harbor's requirements come first where they say something different.
How this works
Suggested first cleaning = date painted + 90 days. State guidance (the 2019 hull-paint guide and the Coastal Commission factsheet) asks boaters to wait at least 90 days after new bottom paint before any in-water cleaning. It is guidance, not a legal requirement, though some harbors make it one (Long Beach and Sacramento Marina, for example, and Berkeley Marina's berth rules).[1][2]
Suggested interval by paint, from the 2019 state hull-paint guide: copper only when needed and no more than once every 30 days; non-copper biocide every 3 to 4 weeks; non-biocide every 2 to 4 weeks (the Coastal Commission says 3 or 4 weeks for soft non-biocide coatings, depending on season and growth).[1][2] We space the planned dates at the short end of the range for warm water and the long end for cool water; that choice, and the May–October "warm" suggestion, are our assumptions. Copper dates are always 30 days apart because that's the guidance's shortest spacing, not a target.
Next date = the latest of: the plan-from date, the end of the 90-day wait, and your last cleaning + one interval. If you don't know the paint type, the copper guidance (the most cautious) is used.
The worked example: copper ablative painted September 1, 2026, planned from November 11, 2026 in cool water. The suggested first cleaning is November 30, 2026, then no more often than every 30 days, and only if the hull needs it.
Related guides: How often to clean your hull in California and Zincs, haul-out and bottom paint.
Sources
- Port of San Diego, LA County Beaches & Harbors, DBW and Coastal Commission. Recreational Boater's Guide to Using Hull Paint in California (May 2019).
- California Coastal Commission. Boat Hull Cleaning and Hull Coating Selection Factsheet (rev. 12-2-19) (December 2, 2019).
- Port of San Diego. Ordinance 3025, amending Unified Port District Code §4.14 (in-water hull cleaning) (October 12, 2021).
- Port of San Diego. Alternative Hull Paints.
- Seaforth Marina. Seaforth Marina Wharfage Rules (December 2023).
- Santa Ana Regional Water Quality Control Board. Resolution R8-2022-0012, Attachment A (Newport Bay copper TMDL) (December 2, 2022).
- LA County Department of Beaches & Harbors. Marina del Rey Copper Paint TMDL: pollution overview (September 6, 2022).
- Los Angeles Regional Water Quality Control Board. Resolution R24-003, Attachment B (Marina del Rey Harbor toxics TMDL reconsideration) (June 27, 2024).
- Port of San Francisco. South Beach Harbor Rules and Regulations (effective January 1, 2026; Resolution 25-84) (January 1, 2026).
- Clipper Yacht Harbor. Harbor rules.
- City of Berkeley. Berth Rental Application (includes welcome packet and BMC chapter 6.20).
- Port of San Diego. In-Water Hull Cleaning BMP Plan Verification & Training Form.
- City of Long Beach, Marine Bureau. Long Beach Marina Environmental Policies (May 2006).
- City of Long Beach. Marina Rules and Regulations (adopted by City Council 4/18/2017) (April 18, 2017).
- LA County Department of Beaches & Harbors. Hull Cleaning (BMP certification, LA County Code §19.12.700).
- Ventura Port District. Ordinance 44 (as amended by Ordinance 47) (October 2008).
- City of Santa Barbara Waterfront Department. Business Activity Permit Policy (Revised 2026) (2026).
- Moss Landing Harbor District. Ordinance Code (amended by Ordinance 215, September 25, 2024) (September 25, 2024).
- Santa Cruz Port District. Santa Cruz Port District Ordinances (August 2018).
- Westpoint Harbor. Rules, Regulations and BMPs (2022) (2022).
- KKMI (Keefe Kaplan Maritime). Contractor & Customer Rules.
- City of Sacramento. Sacramento Marina Best Management Practices.
- Delta Bay Marina. Marina rules.