Ultrasonic Antifouling – worth it or not?

by Adrian on March 1, 2015

We’ve had our ultrasonic antifouling installed and working for a year and a half now and the big question I’m asked is “is it any good, does it work?”

It’s a bit hard objectively gauging performance when we’ve been in very different waters and have travelled so much, but I would say it is helping and is making a difference. The photos below show the state of the hull after a year with just antifoul and after a year with antifoul and ultrasonics.

Here in the Caribbean it’s easer to keep track of it as we can swim around and see the hull every day. It’s not completely eliminating fouling, but I think it is eliminating large amounts of build up and what small weed does grow is soft and easy to wipe off.

Bottom Cleaning

In terms of not having to do any work on the hull, I reckon you could get away with two seasons between haul outs and a proper antifoul in European waters. In tropical waters, I think theres always going to be some build up, but the ultrasonics help keep it at bay.

In the UK it certainly seemed to make a difference. We last did a full scrub and antifoul in June 2013 in Portsmouth prior to installing the ultrasonics. The boat was a year old then, and this is what the bottom looked like.

June 2013 – after a year with just antifouling

  • Bow in 2013 after one year with just antifoul

  • Sides in 2013 after one year with just antifoul

  • Bow Thruster in 2013 after one year with just antifoul

  • Hull in 2013 after one year with just antifoul

  • Aft in 2013 after one year with just antifoul

We hauled the boat out again in June 2014 prior to leaving the UK to check the anodes and do a bit of touching up where needed. This was after a couple of thousand miles sailing around the UK after it went back in the water in 2013 and a long winter stuck in Brighton marina.

Scrubbis Bottom CleaningWe had a bit of growth around the waterline, but not a huge amount anywhere else and the rudders were pretty clean. During the spring every now and again we’d used a Scrubbis to reach under the waterline and dislodge much of the light build-up, which seemed to work well.

This second haul out was not a complete strip and multiple-coat paint job, as it didn’t seem to need it. We spent about 3 hours in total changing the anodes and touching up the hull. We painted the waterline white strip and daubed antifoul in a few areas.

June 2014 – after a year in UK waters with new antifouling and ultrasonics

  • Bow after a year with ultrasonics

  • Beard after a year with ultrasonics

  • Aft Beard after a year with ultrasonics

  • Underneath after a year with ultrasonics

  • Log after a year with ultrasonics

  • Prop and Skeg after a year with ultrasonics

  • Anode after a year with ultrasonics

  • Prop Cleaned and wax prepared

  • Going back in

Since leaving the UK we’ve been in some very warm and fertile waters. Two months in Las Palmas caused a noticeable “beard” on the sunward side, but after a dive and a scrub, it was clean and there wasn’t a huge amount underneath.

The ultrasonics seem to keep the bottom growth to just fine tendrils that are easily brushed away with a coarse scrubbing pad. The anti-foul layer still depletes over time, so repainting is still necessary for hull protection.

Since being in the Caribbean, we’ve experienced much of the same. The waters are very fertile and we’ve had to swim around and scrub off light ‘hair’ every couple of weeks. We’ve had a few barnacles but we don’t have much antifoul left any more, so the ultrasonics are our only defence.

After talking to other cruisers out here it seems a fact of life to have scrub the bottom every couple of weeks in the worst areas (St Martin and Antigua being particularly bad). We were talking to some people last week who had had new antifoul two weeks ago and were already getting weed underneath.

Fortunately with 30°C water, this is not too much of a problem, except for fitting it into the busy schedules.

Our UltrasonicWorks system* initially consisted of two transducers, but 6 months ago I bought another to provide extra coverage for the stern and transom area. This transducer unfortunately died soon after we arrived in the St Lucia, so until I get the replacement fitted we’ve been back to just two, which hasn’t been a huge problem. The faulty transducer also caused a failure of the control box’s shore power circuit, but since the system accepts 12V from a 240V transformer and 12V from the ship’s batteries, I’ve been running it from the battery circuits fine. The system draws just over an amp (at 12V) so does not put a huge load on our electricity demand. We leave it running all the time, and it just clicks away merrily.

*It’s a tough business and Ultrasonic Works are currently focussing on larger yachts and commercial vessels because of the market size, but I believe still work with smaller yacht installations as required.

Note: I have no affiliation with “Ultrasonic Works” apart from being a customer. I paid full price for my system and although they have looked after me when I’ve had problems, there has been no incentive for me to promote their particular product – apart from my own personal opinion that it is the best system you can currently get.

{ 5 comments… read them below or add one }

Kathie Guthrie March 4, 2015 at 09:37

Hi both,
Roger off to Croatia next month to re apply copperguard to Amaazon after 10 years as original coating no longer effective but that could be to Roger’s enthusiasim for excessive sanding! We put antifoul on the keel and like you swim and clean in summer months. Roger will have a long job getting that off to reapply Copper coat which we are generally pleased with.
We also sport a 27 foot Sabre for the price of a new engine, which it has, along with new sails and cooker! She has thick layers of antifoul and has spent the winter in Woodbridge marina but being a bilge keeler I suspect some beaching and muddy scrubbing.
Kathie and Roger


Martyn March 4, 2015 at 08:37

Adrian, Thanks for this, very timely as we are taking Timeless Odyssey out of the water for the first time in two weeks time. I will send you some pictures of what that looks like and I guess that will be a calibration point for Port Solent water temperatures and just an anitfoul coat. We put the boat in the water 1 April last year so it will be 9 months. I will send you an e-mail as I wanted some advice on how you deal with the centreboard during the haul out. Keep on enjoying the BVI etc.


Kat March 4, 2015 at 06:41

Hi Adrian,
Thanks for the update. We’ve applied Seajet Speed (non-biocide, silicone-based) antifouling and we’re hoping that together with the Ultrasonics we’ll have a relatively clean hull. We plan to spend the next 3-4 years in northern waters (North Atlantic, North Sea and Baltic).The Scandinavian countries on the Baltic side are no longer allowing self-polishing antifouling to better protect the marine life there. Sweden is allowing some brands of hard copper-based, but we decide to go all in and try the Seajet Speed (it is said to last 3 years). We’ll see…


Adrian May 5, 2015 at 15:13

Kat, a couple of questions – I’m thinking about the next antifoam and like the idea of the silicon technology. Where did you get your Seajet Speed? How many coats did you apply and how much paint did you use? Thanks Adrian


Kat July 8, 2015 at 15:43

Hi Adrian,
Our boat is a Discovery 55, built in Southampton. They purchased the silicon “Speed” from the local Seajet distributor. I believe they applied three coats and it is supposed to last 3 years. I will send you a status report when the boat comes out of the water this autumn.

Another eco-antifouling paint that sounds interesting is LEAF. It’s still in development but you can google it.


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