Hull Shield Ultrasonic Anti-Fouling System

Hull Shield Ultra-Sound Anti-Fouling System — Now It’s Even Better

Hull Shield HD100

The Hull Shield Ultrasonic Anti Fouling System used sound pulses to keep the bottom clean. 

We recently made a video review of the Hull Shield Anti-Fouling system and the result was overwhelming.  Hundreds of BoatTEST Members are now taking advantage of this no-nonsense/no-maintenance system.  It addresses a problem that’s universal to nearly all boaters who keep their vessels in the water.

Among other things for the “New and Improved” version, the price has been lowered and there are now just two versions — a single unit for smaller boats and a system for larger boats with four transducers.  Both repel the fouling as well as the previous generation Hull Shield.

How Does This System Work

The “dumbed down” version of how this works is to think of the transducers as speakers attached to the inside of the boat’s hull.  They’re all connected to a controller that sends out ultrasound (meaning beyond human hearing) to the transducers that receive the signals and convert them into ultrasonic pulses.  It’s these bursts of sound that work to repel the fouling that comes into contact with the hull and running gear. 

Hull Shield

The sound pulses that Hull Shield sends out are beyond the ability of humans to hear.  In other words, it won’t ruin your peaceful sunset drinks, or sleep for that matter. 

The key phrase in that last statement is “repel the fouling.”  It prevents any new growth from coming onto the hull and sticking.  It doesn’t remove existing growth — that must be done before the system is installed.  Just as is the case with bottom paint, the hull gets cleaned first, then the bottom paint is applied and then the Hull Shield system is installed. 

Hull Shield does not replace bottom paint, but once installed, it eliminates the need to repaint for years. 

There Are Now Two Versions

One of the most notable differences is that there are now just two versions and the only differentiators between the two is the size of the controller and the number of transducers.  Pick from the HD1 with one transducer or the HD100 with four.  The HD1 has a smaller controller and the HD100, naturally, has a larger controller. 

This allows for a much lower entry cost.  Previously buyers of this system had to start with at least a package of two transducers.  With an average range of 20’ (6.1 m) that made no sense to owners of small boats.  Hull Shield heard this and responded accordingly.  Now there’s an option for buying one unit with an entry price of just $499. 

Additionally, the HD100 has a single controller for all four transducers.  All have wire runs that go back to that single controller.  This can get a little inconvenient for boats that have a tight bilge situation or those that require funky cable runs (think catamaran). So, the HD1 gives more flexibility.  Just put a single unit anywhere and all it takes is a wire run to a power source.  Done.

Hull Shield HD1

The HD1 has a single transducer and a smaller controller.  Perfect for entry-level sized boats. 

Transducers are Now Universal

No Need for Separate Hull and Drive Units

This is also a big deal.  There used to be different versions of transducers depending on whether they were to be attached to the hull or the running gear.  They weren’t interchangeable.  Now they are. 

But why have a separate unit for the hull and running gear anyway?  Won’t the connection to the hull also cover the shaft, prop and rudder?  Well it would if there weren’t things such as stuffing boxes and bushings getting in the way.  So, because those things stop the sound from a hull attachment from reaching the running gear, we attach another unit to that running gear.  Problem solved. 

Hull Shield

Here’s a clean bottom, but the underwater light is covered in growth.  A simple look so see that the light was mounted to a rubber flange between it and the hull proves that the sound from the transducers attached to the hull weren’t reaching the light. 

What Else is New?

  • For starters, the new transducers have a 15’ (4.57 m) cable and the packaging includes two additional cables for free. 
  • Power consumption is now lower thanks to the fact that the transducers won’t send a burst signal all at once anymore.  They do it one at a time, so power consumption is much less.  This results in increased overall efficiency while delivering double the power to the transducers. 
  • The control box on the HD100 is fully waterproof.  The HD-1 is water-resistant, but a waterproof version is coming soon. 
  • Because there’s more power at less wattage, the units have lower peak current requirements. 
  • There are now twice as many ultrasound bursts in targeted ranges. 
  • More robust circuitry with advanced fault protection.

A Caveat

After our review of the original Hull Shield system, we got feedback about hulls still having growth.  A few simple questions got to the bottom (get it?) of the problem. 

These problems all stemmed from not cleaning the bottom first.  Or if they were cleaned, it was just by sending a diver down and doing a general scrubbing.  That’s not good enough.  Diver’s only clean what they can see and usually leave behind microscopic growth that then matures over time. 

Hull Shield recommends two cleanings within 30 days to prevent microscopic bacteria and larvae from growing. It’s important to remember that Hull Shield doesn’t remove existing growth, it inhibits future growth.  If critters are already attached, they just enjoy the massage.  It’s a live creature that’s growing, and if it’s not seen… it’s not cleaned.

This is especially important to remember for those southern boats that sit in the mud on the moorings at every low tide.   That’s where the larvae lives… so boats that sit on the bottom will really need that initial cleaning, more so than other boats, before the system is installed. 


  • HD1 $499 (single transducer)
  • HD100 $1,699 (set of four transducers)


We’ve seen the Hull Shield system in action and it works.  Estimates show that the system allows the user to recoup the purchase price from not having to have the hull cleaned by either a haul-out or a diver throughout the season and no need for that scrubbing that removes expensive bottom paint.  It’s a system that has proven itself in military applications for years but was just out of reach.  That is no longer the case.