biofouling on a yacht

Modern Technology Meets Archaic Tradition?

Biofouling is a problem for all boats throughout the world especially those that depend upon efficient movement through the water such as sailing boats & yachts, commercial vessels, and motor yachts. The desire is the same: fuel efficiency (classing wind as a fuel too). Left unchecked, biofouling quickly causes hull damage. The outcomes from antifouling a boat are then:

  • fuel efficiency (from smooth hulls)
  • minimum maintenance & down time (from biofouling)

This article answers the financial question of the cost of antifouling by two methods; an archaic traditional one compared with a modern smart alternative that is also sustainable:

  • antifouling paint
  • ultrasonic antifouling

Of course, money is just one aspect. The choice of antifouling any boat needs to be effective and, these days, environmentally respectful.

Selected Case

For the sake of argument, let’s look at the costs of antifouling this type of sailing yacht.

A 40ft sailing yacht from a distance

A 12 metre (40 foot) sailing yacht with fin keel and auxilliary engine.

Sailing yachts are a demanding example of the importance of antifouling a boat since their power source, the wind, is limited and needs to be optimised. Also, sailing yachts don’t ever go as fast as motor boatss. When underway the relative low speed does not permit as much force to wash away biofouling. Self-polishing antifouling is less likely to work on sailing yachts.

Key Assumptions

The costs here include:

  • materials
    e.g. antifouling paint, components
  • consumables
    e.g. masking tape, brushes, rollers, expoxy glues, sand paper, protective clothing, electricity
  • professional labour
    It could be argued that such work is possible by most boat owners, but then protective clothing, tools, machinery might need to be purchased which a boat yard potentially already has and would not charge for directly.
  • no surprises/ extra maintenance
    Often when a boat is lifted, other maintenance issues are noted, even some of these are caused by failing antifouling paints.
  • environmental charges & disposal charges
    The old waste materials and effulent that is created each time.
  • Insurance, hard-standing rental


  • that the boat starts with a clean hull before the antifouling option is employed
  • any new antifouling paint is compatible with the previous.
    As environmental standards & laws improve, so manufacturers change their formulations.

Let's Compare Paint vs Ultrasound

We’re comparing the established option of antifouling paint, with ultrasonic antifouling which has been available for one or two decades but only in the last few years has it begun to establish itself with pleasure boat owners.

application of antifouling paints is hazardous

Option #1: Antifouling paint

antifouling system installed on the inside of a hull

Option #2: Ultrasonic antifouling

Option #1:Antifouling Paint

Antifouling paint comes in various categories from soft to hard, so called self’polishing; all these products generally contain a biocide, otherwise how would they work? All require protective clothing to apply, and remove.

The weakness of most antifouling paints leads to damage to the underlying hull or other layers of non-antifouling paint. Often these damaged lower layers can not be removed easily and thus damage is done in preparing the surfaces for a fresh coat of antifouling paint.

With antifouling paints, we could calculate the costs in multiple ways of using such products i.e. obtain quotations from boat yards, shop around for suitable paints. However in ‘Googling’ the topic we find some respected websites already have some calculations (which are compatible with our own experience).

As we shall see later, it really doesn’t matter much how the cost is calculated for comparison purposes.

Here’s a range of three sets of prices for different cases and products taken from real reviews and offers readily found online. Take an average of these.

£950 €1,100 $1,300*

  • BlowingOldBoots, 26 Oct 2015 “…antifoul my Rival 41C … £365 …incl. VAT, labour and application materials but not paint.”
  • colind3782, 27 Oct 2015 “…about €1000 Euros inc. IVA in Empuriabrava for the travel lift, pressure wash and two coats of AF for my 33 footer.”
  • Taking into account the length of each of these, and the age of the comments, let’s consider these indicate a cost of £1,000+ [Forums on YBW]

£1,050++ €1,200 $1,460*

  • “…pre-season antifoul package that includes: Lift …scrub…relaunch …five days storage ashore with power supply… choice of quality antifoul paints… Single coat of International Cruiser Uno from £81/m. Two coats of Hempel Tiger Extra from £88/m. Two coats International Micron, Interspeed Ultra or International Trilux from £95/m” [Premier Endevour Quay] Let’s go with 12.1 metres @ £88 per metre.

Did we miss anything? Let us know in the comments.

£1,065 €1,215 $1,470*

Total Cost over 5 years (taking average of the estimates)

Time Required: Each time, the work takes a few days professionally (1-2 weeks by self & additional cost)

€5,859 $7,095*

Arguably some antifouling paints might perform well for more than one season, …yet come at a premium price too.

Professional labour could be replaced by doing the work one’s self but then the paint, tools, protective clothing & respirators, as well as the skill, and time needs to be obtained.

There’s also a cost to our environment, which someone might be able to calculate but most boat owners are ignorant of.

* @ February 2021 exchange rates

Option #2: Ultrasonic Antifouling

Starting with a clean hull, the length of hull at the waterline is likely to allow just one transducer to be adequate, however since there is a bow thruster and the boat is on the limit of capacity for one transducer, we suggest two transducers are employed.

It could be argued that extra batteries, and power sources e.g. solar panels or wind turbines are required but we will assume the existing infrastructure is used since the power consumption is low and shore power can be used when possible.

Read more: Ultrasonic antifouling

Antifouling for up to 20m (66 ft) yachts & tenders
which includes 1 x Control box with 2 x Transducers and ready made 5m & 10m cables

£1,325 €1,490 $1,788*

Installation labour. Self installation is easily possible, but we will assume a professional fee. Time required could be 1-2 hours, but let’s assume 3 hours @ £80/ hour.

£240 €275 $334*

Electricity costs per year (guess)

£24 €28 $33*

Did we miss anything? Let us know in the comments.

Total Cost over 5 – 10 years

Time Required: Takes just a few hours to fit as a one-time exercise.

The expected lifetime of an ultrasonic antifouling system is many more years than 5 years.

£1,635€1,845 $2,218*

There is also flexibility to add additional transducer e.g. if particular attention is required on special areas such as bow thrusters, properller shafts, rudders, and keels. This control box can be connected with four transducers.

This price is a one-time price, there’s no annual maintenance required.

* @ February 2021 exchange rates

Discussion & Conclusion

The difference in cost between the two options is so great that you may now appreciate why we didn’t trouble to pursue the costings to a fine degree. Even if an extra battery, generator with fuel, or solar panel were employed, the cost would still be less than antifouling with antifouling paint.

The benefits are not limited to cost however:

  • An ultrasonic antifouling system is a ‘fit once’ option, not part of annual maintenance. (So choose high quality components).
  • Though boat owners lift their boats for other maintenance, 1-2 weeks for antifouling is not required when ultrasonic antifouling is adopted.
  • Ultrasonic antifouling does not use toxic biocide paint, has low power consumption, and minimal components.

‘Ultrasonic antifouling is cheaper & more effective than antifoul paint in every way.’

Questions & Answers

From the above analysis we can answer some heart felt questions:

How much does ultrasonic antifouling cost?
Less than one-third the cost of antifouling paints. This is even so unfair as to consider the life-time of an ultrasonic antifouling system is just five years since they have no moving parts or parts that wear, they have a much longer life expectancy.

How much does antifouling paint cost compared to ultrasonic antifouling?
If it is assumed that an ultrasonic antifouling system only has a life of five years, then antifouling paint costs more than three times as much over five years as ultrasonic antifouling. Antifouling paints are an annual cost, whilst ultrasonic antifouling is a one-time cost. An ultrasonic antifouling system costs slightly more than one application of antifouling paint.

How much does professional antifouling cost using antifouling paint?
About £90 – £133 per metre (depending on the overall length since longer boats are also generally wider.) See the quotations above from real sailors and antifouling companies.

How sustainable is ultrasonic antifouling?
Ultrasonic antifouling uses no biocide paints; the electronics are designed for the harsh environments on boats and therefore have long life; the power consumption is so low that solar or wind power can be used.

Example Ultrasonic Antifouling Systems

Whatever size your boat, there’s an option available. It’s scalable too, and customised to your specific needs. If you need a little more antifouling, it’s easy to add extra attention to parts of the boat and all underwater surfaces whether hull, keel, rudder, propeller, or other.

What Do You Think?

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