Underwater Hull Cleaner's Best Management Practices (BMPs)

Underwater hull cleaners can lower operation costs, assist their industry, clients and the marine environment by using best management practices (BMP's) to reduce pollution and extend the life of hull paints.

Objectives for BMP Use

• Prevent paints, especially those with copper, from entering the water and sediments.
• Keep paint intact on the hull and remove fouling growth to reduce drag & fuel use.

Hull Cleaner BMPs⁵

• Wait 90 days after applying new paint. Paints release more toxicant when new.
• Soft sloughing or ablative paints release toxicant & paint to water when cleaned. On these boats, clean only running gear and zinc anodes.
• Use only a piece of “carpet”, sponge & other soft materials to clean the hull.
• Use soft nylon or similar material on rotary brush machines.
• Use stainless steel brushes & pads on non-painted, metal areas only.
• Use more rigorous cleaning pads only as needed to remove hard marine growth.
• Do not sand or strip hull paint underwater.
• Bring zinc anodes back to shore; recycle or dispose properly.
• Clean gently to avoid creating a plume or cloud of paint in the water.

Advising Boat Owners^4,5
The following information may be useful to answer client questions on hull protection & maintenance.

Maintaining the Hull and Paint

• Properly applied and maintained paints protect the hull from fouling organisms & improve performance of the boat.
• Correct application also extends paint life by reducing amount lost to harbor.
• Allow 90 days after applying new bottom paint before cleaning underwater.
• Regularly scheduled hull cleaning and Maintenance reduces hard marine growth and hull drag³.
• Repair paint bonding problems at haul out to avoid further chipping and flaking of paint into the water.

Protection from Fouling Growth
Toxicants in some hull paints limit cleaning options & increase toxicant amounts in marine waters. The following may be helpful to clients in choosing anti-fouling strategies.

• “Soft” sloughing and ablative (self polishing) hull paints release copper when cleaned underwater. Refrain from underwater cleaning⁵.
• Hard finish, conventional anti-fouling paints release less toxicant with underwater cleaning.
• Polyurethane and silicone paints contain no toxicant & do not rub off during cleaning². Don't leave most polyurethane painted hulls in water over 72 hours.
• Store infrequently used boats on land. Check local requirements & facilities for storage locations.
• Floating hoist systems hold the boat out of the water in the slip.
• Ask a repair facility if your hull paint remains effective after boat is stored out of the water².

References:

1. “Anti-fouling Bottom Paints and Fishing Vessel Efficiency” (Jeff Longmore)
2. Baywatch, A guide for Boaters (Environmental Health Coalition)
3. “Cutting Fuel Costs: Alternatives for the Commercial Fisherman” (Dewayne Hollins et al.)
4. Soundwatch, An Environmental Guide for Boaters (48 North)
5. Underwater Hull Cleaning Best Management Practices (Bear Underwater Services).

For more information on hull paints, ask experienced boaters & boatyard owners and see our publication, “Selecting a Hull Paint for your Boat”. Write to:
Cooperative Extension - Sea Grant, 5555 Overland Avenue, Building 4, San Diego, California 92123

Information provided for educational purposes. Ask agencies about regulations in your area.

We wish to thank David Bear and the many other advisors & reviewers!

Authors:
Erika J.A. McCoy, Program Representativeand
Leigh T. Johnson, Marine Advisor

This work is sponsored in part by NOAA, National Sea Grant College Program. Department of Commerce, under grant number NA36RG0537, project number A/EA-l, through the California Sea Grant Program, in part by United States Environmental Protection Agency, under grant number NW009982-01-0, in part by the California State Resources Agency, in part by the University of California Division of Agriculture and Natural Resources and in part by the County of San Diego. The views expressed herein are those of the author and do not necessarily reflect those of the sponsors or any of their sub-agencies. The U.S. government may reproduce and distribute for governmental purposes.