Antifouling Paint Test 2016-17
Eco-Friendly Beats Heavy Metal
by Chris Doyle
For years boatowners have been relying on heavy metals, particularly copper, to keep boat bottoms free of growth. This year I was delighted to test the new eco-friendly Seajet 038 Taisho. This paint has no copper and relies on a biocide called Econea, which can be used in relatively small amounts and which breaks down quickly into biodegradable components. It can be used on aluminum and steel as well as wood and fibreglass. Zinc pyrithione (often used in anti-dandruff shampoos) is used as herbicide. Seajet 038 is a soft paint and rubs off easily.
The paint I compared this with is a high-tech hydrolyzing antifouling that uses copper. It is more resistant to rubbing than the Seajet.
I recently compared these paints in various conditions in the Eastern Caribbean over six and a half months. After last summer on the hard, I had each hull of my 40-foot catamaran, Ti Kanot, painted with a different type of antifouling — the environmentally friendly paint on the port side and the copper-based paint on the starboard side.
Ti Kanot was splashed on November 18th, 2016.
First thorough check: December 23rd, 2016
Normally I would expect both hulls to be completely clean at this stage, however, last year I had to relocate my mooring in Prickly Bay, Grenada and I think I may have it placed in a barnacle mother lode. Ti Kanot lay there for a couple of weeks before heading north. At one month I had noticed barnacles, particularly on the starboard (copper-based paint) hull, so on December 23rd, since I was in the Saintes with clear water, I decided to take a careful look and remove any barnacles that were present.
While overall the starboard (copper-based paint) hull looked reasonably good, closer inspection showed there were hundreds and even thousands of small barnacles in most hidden areas. These included under the hulls from the rudder to the keel, the back and front of the keel on both sides, about a third of the rudder on both sides, and under the bow on both sides. In addition there were a couple of barnacle-growth areas and significant slime on the inside of the keel.
The port hull (Seajet 038 Taisho) for the most part was completely clean. I did find a small band of barnacles under the rudder, and one or two on the rudder, but that was it. The number of barnacles on this hull was minimal, probably between one and five percent of the number on the other hull.
Second thorough check: January 21st, 2017
About two weeks of the time between the last check and this one was spent in Simpson Bay Lagoon, St. Maarten. My previous experiences there let me know I could expect quite a lot of barnacle and other growth in this bay. On hoisting the anchor, the ropes attached to it were pretty horribly covered in weed, which is typical there.
On the starboard hull (copper-based paint) there were hundreds, and probably thousands of barnacles. They were not all over: the upper part of the hull on both sides was reasonably clean from the mid-section to the stern, though there were some barnacles widely spaced over the area, and some coral-type growth toward the stern. The barnacles were heavy and numerous under the entire hull, and also on the bow on the side of the hull that is usually shaded. There were also quite a few barnacles on the other side of the bow. The keel had barnacles along the front and back edge. The rudder had a few dozen barnacles on each side.
The port hull (Seajet 038 Taisho) was impressively clean. There was a small but heavy band of barnacles on the underside of the hull in the rudder area and also one or two on the rudder. I found one or two on the bow. Apart from that, the aft side of the keel had a row of barnacles. There was now some slime on this hull, and I was not sure whether to wipe it off or leave it. I decided leave it on for the moment.
Barnacles on both hulls were removed.
Third check: February 17th, 2017
Barbuda — a lovely place to check and clean the hulls! I took some photos this time too, using a tiny wide-angle camera. My crew, Lexi, looked for the first time and said, “The port side is much better than the starboard.”
As I have found in all my antifouling tests to date, the worst places are the insides of the hulls, under the hulls and the rudder area. The copper-based paint on the starboard hull was still performing well on the outside of the hull, but the inside had barnacles nearly all over, and even if the density was not very high, there were hundreds. There were fewer toward the bow but there were barnacles under the bow. The highest density was under the hull at the stern and down the rudder. The keel had also gained a liberal dose of barnacles all over the inside, with fewer on the outside.
In general, the Seajet 038 Taisho paint on the port hull was impressively clean again. There were barnacles, but only a few dozen. These were concentrated in the stern under the hulls, and some on the rudder. There were also a few under the hulls in the bow, plus a rather curious little green weed growth that came off with very gentle wiping. But for the most part the rest of the hull was barnacle and weed free. There was a slime over much of it, some with a few patches of very light white weed (this was common on both sides) that came off with a gentle wipe, but after trying to remove a patch I decided that I would lose too much paint so I left it alone. We could not but help notice that after removing the barnacles, a lovely baby octopus had decided to join us on this hull.
Fourth check: March 24th, 2017
For the first time, there was not much difference between the paints. We must have been in cleaner water with fewer barnacles. There was some weed.
On the starboard hull (copper-based paint) there were maybe a dozen barnacles on the rudder and the stern up to the keel on the inside, and the same number on the outside. There were very few barnacles on the hull above the keel on the inside, and perhaps half a dozen barnacles on the hull above the keel on the outside. We saw about two dozen barnacles distributed on both sides of the bow section.
There was some weed spread about in various places on the hull, particularly around the rudder and under the stern. Green weed came off quite easily; red weed was harder and took more scrubbing.
On the port hull (Seajet 038 Taisho) there were maybe a dozen barnacles on the rudder and the stern up to the keel inside, and very few barnacles on the rudder and the stern up to the keel outside. No barnacles were found on hull above the keel on either side of this hull. On the bow on the inside there were about three or four dozen barnacles, but very few on the bow outside.
There were some patches of light-green weed in various places over the hull; the heavier bits could be removed very easily with a gentle touch. But paint was also removed, so very little wiping was done.
Fifth check: April 26th, 2017
This time, for the first time, both paints were looking scuzzy, though the scuzz was mainly slime and weed rather than hard growth. The copper-based paint had both a light white weed, which came off pretty easily, and a red weed that was hard to remove. The Seajet 039 Taisho had plenty of white weed, but happily no red weed. Weed seems to favor sun, so most of the growth was on the outer sides of the hulls. There were not many barnacles, but there were a few more on the copper-based paint side.
On the starboard hull (copper-based paint) the rudder was at least 50 percent covered, both inside and outside, with red weed plus a few barnacles. The aft part of the hull had a lot of weed, including the red weed and maybe a dozen barnacles. The weed continued towards the bow, but there was less of it, and there were a few dozen barnacles, mainly small. The outside of had a lot of weed, including patches of red weed, but only a few barnacles. Most of the weed was removed, but it was almost impossible to remove all, especially the red.
On the port hull (Seajet 038 Taisho) most of the inside of the rudder was clean, though there was a little white weed; on the outside, the bottom part had white weed. Three barnacles were found on the front on the rudder, and two on the stern of the boat. Most of the hull was clean on the upper part, getting white weed farther down, which was quite long in patches, especially on the outer side of the hull. Apart from the barnacles mentioned there were maybe two more up in the bow; otherwise there was no hard growth. Most of the weed was removed and it came off quite easily.
Haulout: May 31st, 2017
Over years of testing paints, I have found that barnacle loads vary hugely depending on where you anchor, and that all antifouling grows barnacles when pushed. I’ve also learned that I had better move my mooring in Grenada because it is in Barnacle Central; the water there often looked very soupy. Ti Kanot hung on my Prickly Bay mooring again for a couple of weeks before going to Trinidad to haul, which I figured would be a good test. As it turned out, it was maybe too good.
My first impression on hauling out was that both sides were pretty much covered in barnacles, nearly all of them tiny barnacles packed together. However, closer inspection, part by part, revealed there was a significant difference; the copper-based paint was pretty much covered in barnacles everywhere. It looked like less than 20 percent of the surface was free of barnacles. The Seajet 038 Taisho had much larger areas free of barnacles, with maybe about 60 to 70 percent of the surface area remaining clean.
In this test the eco-friendly Seajet 038 Taisho significantly outperformed the more traditional copper-based paint. Econea is particularly good at dealing with marine critters: barnacles, corals, hydroids and the like.
In this test Seajet 038 Taisho proved more resistant to growing barnacles from the beginning. I had dozens, hundreds, and even thousands on the copper-based paint and very few on the Seajet 038. But sometimes, when we were in relatively barnacle-free water, very few barnacles attached to either hull. Barnacle growth is very much a matter of location, and both paints did grow many barnacles in the last month of the test, but the Seajet 038 Taisho had far fewer than the copper-based paint.
Regarding weed, the copper-based paint grew weed, not only the white weed, which comes off easily, but also a red weed which was hard to scrub off. After a few months the Taisho grew only some white weed, which was easy to remove.
Such proven good performance is a breakthrough and a major achievement for an eco-friendly paint. It gives boatowners a way to keep our boats clean in a more environmentally friendly way (I could not find too much on the environmental effects of zinc pyrithione in the a marine environment, but from what I did read it did not seem to be a big issue) — good news when choosing paint for next season.
This may well be the future of antifouling.
Copper: A Little is Good, a Lot is Not
Copper is a naturally occurring essential micronutrient required for normal growth in both plants and animals. As such, we all have mechanisms to deal with normal copper levels in their environment.
However, as we can see from its popularity as an antifouling agent, exposure to elevated levels of copper is highly toxic to aquatic organisms, and antifouling paint can be a cause of concentrated levels of dissolved copper in waters around marinas, boatyards and anchorages.
Fish and crustaceans are ten to 100 times more sensitive to the toxic effects of excess copper than are mammals. The effects of copper on aquatic organisms can be directly or indirectly lethal. Gills become frayed and lose their ability to regulate transport of salts such as sodium chloride and potassium chloride into and out of fish. These salts are important for the normal functioning of the cardiovascular and nervous systems. When the salt balance is disrupted between the body of a copper-exposed fish and the surrounding water the death of the fish can result. High levels of copper also adversely affect the sense of smell in fish, which rely on their sense of smell to find food, avoid predators and migrate.
Because copper is an algaecide it is not surprising that it causes decreased algal growth when there is enough of it in the water. Because algae are at the base of food chains, the amount of algal biomass present in an aquatic ecosystem will affect the amount of food available for aquatic animals including shellfish, fish and aquatic mammals.
Too much of a good thing can be bad.
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