The great UK antifouling test for cruising yachts

20 antifouling paints tested in 13 UK locations: which works best where you keep your boat?

Welcome to the biggest and most in-depth test of antifouling paints ever carried out by a magazine in the UK.

Previous tests have focused solely on one location, but as fouling conditions vary greatly between ports and harbours around the coast, we reasoned it would be of far more use to boat owners around the country if they could draw on some test results closer to home when choosing their antifouling paint from the bewildering range of options out there.

We spent two weeks painting our plywood test panels, in the process consuming 350m of masking tape, 15lt of primer and 40 (cheap) paintbrushes, not to mention the 20 antifouling paints themselves. And now, seven months and 4,400 miles of driving later, here are the results of our round-Britain antifouling test.

How we tested them

We primed our 26 test panels with International’s Interprotect Epoxy Primer before using a tie-coat primer where required and applying each of our antifoulings with the recommended number of coats (two, in most cases). We applied the paints in strips, with an 11mm unpainted strip between each paint, acting as a control surface.

We restricted the test to single-pot eroding paints in blue: these are the most popular antifoulings for cruising boats. With the paint dry, we loaded the boards into a trailer and drove them round the country, installing them facing the sun where possible and aligned with a modest tidal flow to simulate their normal usage as much as possible. We installed the boards in late March, returning in early October to remove them and inspect the results.

There were big differences between paints on the boards in terms of the amount of fouling they retained. What was telling was that even the worst-performing paints showed a massive improvement over the unprotected control surfaces – so even a cheap paint is better than nothing. However, the best performers were in a league of their own: read on to find out which paint you should choose.

Do you need antifouling?

We left the backs of our test boards as bare primer to act as a control. The good news is that without exception, every antifouling paint showed a marked improvement compared to the bare panels. Fouling differed in a big way between each of our 13 locations, from Dunstaffnage, which had minimal growth, to Hamble, which showed by far the worst. Lowestoft and Waldringfield, on the East Coast, were also bad. Whitby and Inverkip had very heavy slime, while Neyland and Caernarfon saw moderate shell and weed growth.

Click here to download a PDF of the great UK antifouling showdown as it appeared in Practical Boat Owner magazine’s January 2016 issue.

How the panels looked after more than six months at sea…

The results

North Wales – Caernarfon: Fouling – Moderate

In Caernarfon the better paints had only light slime, while the worst-performing had heavier slime and some brown weed growth. There was no shell growth on any of the paints.

Top 5 paints
1. Seajet 033
2. Micron Extra
3. Teamac ‘D’
4. Cruiser Uno
5. Nautix A3

South Wales – Neyland: Fouling – Moderate

Neyland had some heavy slime which had been visited by some local mullet, leaving their distinctive smear marks – also a useful test of how well the fouling was attached.

Top 5 paints
1. Hempel C.P.
2. Seajet 033
3. Micron Extra
4. Teamac ‘D’
5. Cruiser Uno

Scotland – Inverkip: Fouling – Moderate

Inverkip’s boards showed thick slime, but none of the paints had green weed or shell growth, unlike the untreated surfaces. Some differences were evident, with Seago’s High Performance best.

Top 5 paints
1. Seago H.P.
2. Nautix A3
3. Precision P.
4. Teamac ‘D’
5. Nautix A.P.

Scotland – Rhu: Fouling – Light-moderate

Growth in Rhu was relatively light on the better-performing paints. Seajet’s 033 was best here, with International Cruiser Uno, Teamac’s ‘D’ and Micron Extra also doing well.

Top 5 paints
1. Seajet 033
2. Int. Cruiser U
3. Teamac ‘D’
4. Seajet 038
5. Micron Extra

Scotland – Dunstaffnage: Fouling – Light

Dunstaffnage had the coldest water of all our locations and the least slime. There was no weed or shell growth on the painted panels, and some differences between most and least effective paints.

Top 5 paints
1. Hempel C.P.
2. Precision P.
3. Seajet 038
4. Seajet 033
5. Int. Cruiser Uno

Scotland – Port Edgar: Fouling – Moderate

In Port Edgar, the boards were damaged by a tyre fender tied to the pontoon by a workboat crew, so four samples were rendered invalid, unfortunately, with paint and fouling wiped off.

Top 5 paints
1. Seajet 033
2. Micron Extra
3. Seajet 038
4. Jotun NonStop
5. Precision Prem

Northeast England – Whitby: Fouling – Heavy slime

Fouling in Whitby consisted of heavy slime. Seajet’s 033 and 038 were far and away the best, with the fouling washing off to leave a clean surface. Micron Extra was also effective, but not to the same degree.

Top 5 paints
1. Seajet 033
2. Seajet 038
3. Micron Extra
4. Cruiser Uno
5. Teamac ‘D’

East England – Lowestoft: Fouling – Moderate

The slime at Lowestoft was underpinned by some heavier growth in places. There were big differences in performance, with colonies of small shrimp inhabiting the heavier areas of slime.

Top 5 paints:
1. Seajet 038
2. Seajet 033
3. Seago H.P.
4. Hempel C.P.
5. Flag Perf. Extra

East England – Waldringfield: Fouling – Moderate

As at Whitby, Seajet’s 033 shed nearly all fouling as it was pulled out of the water, handing it best prize here. Hempel Cruising Performer, Nautix A3, and Seago’s High Performance paints also did well.

Top 5 paints
1. Seajet 033
2. Seajet 038
3. Hempel C.P.
4. Nautix A3
5. Seago H.P.

East England – Fambridge: Fouling – Moderate

In Fambridge, Seajet’s 033 and 038 again shed most slime as the boards were removed. Micron Extra was fairly clean, with Flag Performance Extra and International Cruiser Uno doing well.

Top 5 paints
1. Seajet 033
2. Seajet 038
3. Micron Extra
4. Flag Perf. Extra
5. Int. Cruiser Uno

South Coast – Chichester: Fouling – Moderate

In Chichester, Seajet’s 033 was by far the cleanest, coming out almost slime-free. Micron Extra was a close second. Seajet 038 and Teamac ‘D’ were next best, with Precision Premium also doing well.

Top 5 paints
1. Seajet 033
2. Micron Extra
3. Seajet 038
4. Teamac ‘D’
5. Precision Prem.

South Coast – Hamble: Fouling – Moderate

Seajet’s 038 was best in the fast-flowing mouth of the Hamble, with their 033 product not far behind. Micron Extra was relatively clean, as was Teamac’s D, with Jotun NonStop also moderately successful.

Top 5 paints
1. Seajet 038
2. Seajet 033
3. Micron Extra
4. Teamac ‘D’
5. Jotun NonStop

South West – Plymouth: Fouling – Moderate

Seajet’s 033 performed best at Plymouth Yacht Haven, with 038 also doing well. Micron Extra was also a strong performer, with the same company’s Cruiser Uno and Jotun’s NonStop also doing well.

Top 5 paints
1. Seajet 033
2. Seajet 038
3. Micron Extra
4. Int. Cruiser Uno
5. Jotun NonStop

The PBO verdict

Boards were submerged during the summer months

This is the biggest test we’ve ever carried out at PBO, with a significant investment of time, money and effort involved in buying, priming, painting, delivering and installing the test boards.

We were careful to install the panels as similarly in orientation, location and tidal characteristics as possible – facing the sun, and aligned to the tide to simulate a boat’s mooring and occasional use.

We were fortunate that only one set of panels suffered damage (in Port Edgar, where a tyre fender was tied on in front of the board, damaging the paint and removing the fouling from a few of the panels).

Our host locations kindly monitored the boards and their growth throughout the year. When we took them out, in early October, the water was at its warmest and the fouling greatest. Any later and the fouling would have begun to drop off as the water cooled.

Of course, our static panels represent a ‘worst-case’ scenario – that your boat doesn’t move all year. The more you use her, the better your antifouling will perform, and the less the fouling will adhere.

Some interesting results

A board from Whitby as removed, showing
how the slime ran off the two Seajet
products, 038 and 033

With the results in, the 26 panels, 20 paints and 13 locations have generated a lot of data.

Sifting through has shown up some interesting results. The most telling of all is that every paint tested showed a big improvement in fouling when compared to the control areas, which had heavy weed, shell and kelp growth. None of the paints had any barnacles or other shell growth, or any long fronds of weed – except in some cases along the waterline.

While no single paint kept everything fouling-free in all areas, what particularly surprised us was the dominance of one paint – Seajet’s 033 Shogun was best in eight of our areas, with the company’s 038, due to be released in 2016, also doing well.

These paints shed slime and other fouling so effectively in many places that when pulled out of the water, they appeared clear.

Other paints also performed reasonably well. International’s Micron Extra was a comfortably one of the top paints all around the country. Other good performers included Teamac Antifouling D plus, made by an independent family business located in the north-east, Precision Premium, also made by Teamac, and Nautix’s A3. Seago High Performance also performed well in places. Hempel’s Cruising Performer and Jotun’s NonStop did well in some areas of the country. Boero’s Mistral NF had some reasonable results, and Flag Performance Extra did well on the East Coast.

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Increased regulation

Of course, most boat owners won’t be interested in which brand is best all around the country: most boats stay put in their home port for most of the season, which is why it’s best to look at the results for your location, or the nearest port to your own.

It’s reassuring that the better paints on test proved mostly effective in keeping fouling at bay, as manufacturers have had to deal with increased regulation – especially the EU’s Biocidal Products Directive, which has led to tweaks and changes in antifouling products.

Cost is another interesting factor. Paints seem to split into two camps – around £40-50 per 2.5lt tin and around £100 per tin. The circa £100 camp tended to do better than the circa £50 camp – the more expensive bracket, which often has greater concentrations of copper and other biocides, is likely to be more effective.

As published in Practical Boat Owner magazine’s January 2016 issue. Prices correct at the time of going to press.