Cavitation cleaning vs scrubbing: what each one does to your bottom paint

Both methods get the growth off. The difference is what is left on your hull afterward. Scrubbing drags an abrasive across your bottom paint and takes some of it every single pass. Cavitation knocks growth loose with collapsing water bubbles, without grinding the surface.

What scrubbing actually does

A diver goes down with a brush, a pad, or a scraper and works the growth off by force. It works. It has worked for decades and most of the boats in Tampa Bay have been cleaned this way.

The catch is that antifouling paint is soft on purpose. Ablative paint is built to wear away slowly so it keeps exposing fresh biocide, which is what stops growth from setting in the first place. When you put an abrasive against it, you are accelerating the one process the paint was engineered to do slowly.

So every scrub does two things at once. It takes the barnacles off, and it takes off some of the protection that was keeping the next round of barnacles away.

What cavitation actually does

Cavitation cleaning runs a stream of water that forms tiny vapor bubbles. Those bubbles collapse against the hull, and the energy of the collapse breaks the bond holding growth to the surface. The growth lets go. The tool never has to grind against the paint to make that happen.

We run the Cavidyne system for this. Hard growth comes off, the paint underneath stays where it is, and you keep the protection you already paid for.

Side by side

Why the paint is the part that matters

People think of a hull cleaning as a cosmetic job. It is not. The bottom paint is the thing doing the work between visits, and a cleaning either respects that or eats into it.

Run the arithmetic on your own boat. If you are cleaned monthly, that is twelve passes a year across your bottom paint. A method that takes a little off each time takes a lot off across twelve. That shows up as a bottom job a season earlier than you planned, and a haul out, and a week without the boat.

The cheapest bottom job is the one you do not need yet.

When a brush is still the right tool

Being straight about this matters more than selling you one method.

• Running gear. Props, shafts and thrusters are bare metal with no antifouling to protect. There is nothing to preserve, so mechanical cleaning is fine and sometimes faster.
• Hard epoxy or unpainted surfaces. If there is no ablative coating to wear through, the main argument against abrasion goes away.
• Very heavy first cleans. A hull that has been left a year sometimes needs mechanical help to get back to a baseline. After that first pass, the schedule keeps it from happening again.

The point is not that brushes are bad. The point is that using one on healthy ablative paint, every month, for years, has a cost that nobody tells you about until the bottom job comes early.

What to ask before anyone gets in the water

• What method are you using on the painted surfaces?
• How do you handle the running gear, and is it included?
• Will you tell me what you found down there, or do I just get an invoice?
• What happens on the first clean if the growth is heavier than expected?
• Are you licensed and insured?

Any diver worth hiring answers all five without hesitating.

Common questions

Does cavitation cleaning damage bottom paint?

No. That is the entire reason to use it. The bubbles break the bond between the growth and the surface instead of grinding the surface down, so the paint comes through a cleaning largely intact.

Is it slower than scrubbing?

Not on a boat that is on a regular schedule. On a hull that has been neglected for a year, any method takes longer, because there is simply more to remove.

Will it get barnacles off, or only slime?

It takes off hard growth. That is what it is built for. Slime is the easy part.

If you want to see it done on your boat, read how we run cavitation cleaning or get a free estimate.