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Underwater Services International, Inc. (USI) provides the very best in hull cleaning services. Our 4- to 9-person teams serve the entire East, West, and Gulf Coasts along with select International Ports. Rapid turnaround cleanings can be provided in as little as 12 hours (additional charge and certain conditions apply). Our team takes an average of 48 to 72 hours to provide a total ship cleaning (hull, propellers, rudder, sonar dome)-and we work around your crew-you do not work around us. USI is totally self-contained.

How Do We Do It!

USI's equipment is diver-operated, hydraulic-driven, rotary multi-brush cleaning units. Numerous brush material and abrasive discs are available to handle almost any type of marine fouling on any underwater surface. The speed of brush rotation is adjustable by the diver to produce exactly the type of cleaning action required-to go gently and rapidly over surface with light slime or more slowly to tackle heavy shellfish. The scrubber bristles lay flat against the hull, cleaning it with a sweeping motion instead of gouging it. The diver simply guides the unit over the hull in lateral passes from bow to stern and completes the job by polishing the propeller, running gear, etc.

USI's equipment is larger, faster, and more controllable than most other hull cleaning units. Our scrubber moves across the hull at a variable speed of 18.3 to 36.6 meters per minute and at successive depths. This scrubber adheres to the underwater surfaces of the hull with a force exceeding 1000 pounds. The traction of the wheels is 700 pounds, which enables the scrubber to travel at variable speeds against most tidal forces. The cleaning brushes on the scrubber are made of either stainless steel wire bristles, which are specially designed to ensure that their tips do not point directly into the hull, or polypropylene bristles for anti-fouling reactivation and removal of soft algae. This scrubber allows the USI teams to provide quicker turnaround, less downtime, and more consistent cleaning with minimal paint deterioration.

Benefits to USI's Routine Maintenance Program

Ships are always ready to achieve the performance numbers required.
  • Cost of routine maintenance is far less than the loss of fuel efficiency caused by a fouled hull or propeller.
  • Anti-foulants are rejuvenated.
  • Inspections for dry-dock repairs allow more accurate repair estimating saving time and money.
  • Scheduled inspections and cleaning are far less expensive.


Quality work completed efficiently and cost effectively.

Cleaning accomplished while the ship is at anchorage or at dockside with an average 48- to 72-hour service for complete cleaning (rapid turnaround cleaning can be provided in as little as 12 hours).

Minimal scraping or removal of the hull's anti-foulant coatings.

Time and money savings with less frequent dry dockings.

Underwater pictorial survey of the hull providing documentation of the hull's condition before and after cleaning.

Routine maintenance program including hull, propeller, rudder, sonar dome cleaning and propeller polishing.

Professional uniformed staff with specialized training.

Underwater closed circuit video revealing any condition warranting early corrective action or repair.

Pre-dry-dock cleaning requiring less time in docks and significantly reduced waste disposal charges.


Once the anti-foulant coating begins to develop a layer of slime, more advanced stages of fouling will begin to appear, including tubeworms and barnacles. If a diver does not intervene, these shellfish can actually penetrate the coating and inflict permanent damage. The staged process to permanent barnacle damage is depicted in this figure.

Stage 1: Hull layers.

Stage 2: Development of slime, grasses, and an immature barnacle. Cleaning the hull now would allow a softer bristle brush to be used resulting in less paint damage and rejuvenation of anti-foulants.

Stage 3: Continued barnacle growth, now beginning to penetrate the protective coating. Cleaning at this stage will require a combination bristle and wire brush.

Stage 4: The barnacle has grown and penetrated the protective coating, putting the barnacle in direct contact with the steel hull causing permanent hull damage. At this stage the anti-foulant is almost non-existent. If the hull is cleaned during Stage 2 when the immature barnacle is just beginning to develop, permanent hull damage can be avoided.


The propeller is particularly vulnerable to marine fouling since it is an unpainted surface that must remain clean and shiny for proper operation. The U.S. Navy determined that propeller fouling, despite its small surface area, can generate energy losses amounting to half that of the hull itself so maintaining a clean propeller is critical. On military ships, the unpainted surfaces such as propellers, rudders, and sonar domes are cleaned twice as often as the hull surfaces. The propellers are also polished routinely to reduce friction and ensure that the propeller operates at optimum efficiency. Even with routine maintenance, surface roughness can occur as a result of erosion, corrosion, or from tubeworm tracings. This roughness alone can increase fuel consumption up to 10 percent.


The optimum interval between the periodic cleanings and inspections that comprise a preventive maintenance program will vary with the type of vessel, the location of the vessel, and its service profile (speed of operation, idle time, etc.). The type and condition of bottom coatings will also have an effect on the cleaning interval. Large vessels typically have several layers of coatings, up to 6 millimeters thick, and generally operate 4 to 6 months between hull cleanings.

The location of the vessel also has a substantial influence on the rate of fouling since marine organisms flourish in warm tropical waters. The U.S. Navy has established geographic fouling zones, indicating the frequency with which the hull and unpainted surfaces (propellers, rudders, and sonar domes) should be cleaned for vessels operating within each geographic zone. In Navy Zones 1 and 3, propeller cleaning is recommended up to six times a year and hull cleaning is recommended up to three times a year

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