Sanding Antifouling – a Poisonous Matter

“If it can kill marine organisms, it can kill you too.”
“Sanding antifouling? – NEVER!”
“I sanded off my antifouling. It took weeks and would never do it again.”
“Try chemical paint removers!”

Osmosis blister on the hull of a Kelly Peterson 44 bluewater cruiser.

These are just a few of the many statements I was confronted with when researching how we should remove our antifouling. But what is the right way?

We’ve been at Cabrales Boatyard for some time now and have settled in. It’s great to be here. The days are filled with small tasks and pass by in a flash. Slowly but surely we are entering refit mode. We set schedules and make lists of what needs to be done practically every day. This is how we want to avoid getting into a vacation deadlock and forgetting things. The goal of everyone on the boatyard is clear – back into the water as quickly as possible!

Sanding the antifouling and the topsides

The first big item we want to take care of is the painting of Milagros‘ hull. The paintjob is extremely old. We want to remove the old antifouling from the underwater and sand the topsides (the hull above the waterline). As you can read in Carmen and Iñaki’s blog posts, the sun burns mercilessly from the sky in the Mexican summer. What can be a horror for us humans is perfect for drying out the fiberglass of ship hulls. This is important for new paintjobs, as the hull should have as little moisture as possible for new paint. So we decided to tackle the hull as the first major project, starting with the underwater hull. An important question is: How do we want to remove the antifouling? This project has its pitfalls.

Sanding antifouling is necessary on this underwater sailboat hull
Our hull needs to dry out

Antifouling is toxic!

The composition of antifouling paints contains biocides to prevent marine organisms from growing on the ship’s hull. If you have too much growth (fouling) on ​​your boat, this can have a noticeable effect on its performance. In the case of large container ships, for example, this is reflected directly in the fuel consumption. That in turn costs the shipping companies dear money. The effects of the biocides and the chemicals in the antifouling paints should not be underestimated in environmental terms and are toxic for the human body.

A big container ship making its way on the pacific side of the Baja california peninsula.
For those big guys having a clean underwater hull is key.

Removing antifouling – the boat itself does that too

The antifouling on our boat’s hull is a self-polishing one. This means that the antifouling paint is removed by the water while moving through it and, so to speak, renews itself and releases the biocides constantly. The protection against fouling remains active until the Antifouling layer is gone and needs to be renewed. Removing antifouling made easy. Millions of boats happily distribute biocides every day in the world’s oceans. Sailors are great environmentalists – yeah right. Companies like Coppercoat try to counteract this. In general, a lot of research is being done on how to prevent fouling on ships in a more environmentally friendly way. As with everything concerning our environment, the rethinking happens a little as about 20 years too late.

How to remove antifouling?

The antifouling phenomenon is not good for the environment and equally not good for humans if they want to remove the antifouling. Therfore, great caution is required. Antifouling dust should not be inhaled under any circumstances. I did some research beforehand about the different ways how to remove antifouling, which would be:

  • Sanding the antifouling (wet or dry)
  • Stripping with chemical paint removers
  • Dry scraping
  • Sandblasting

While the first three options are relatively cheap, hazardous to health and extremely labor-intensive, the latter is quick, more harmless, but expensive. Hence the question, which type do we use? We did a little research at the Cabrales Boatyard and practically all parties opted for sandblasting. Nevertheless, I wanted to try sanding the Antifouling. Anyone who knows me sees – why easy when you can also go the difficult path.

Damaged underwater paint paint before boat refit, time for sanding antifouling
Time to get rid of that old goo!

These Swiss are crazy!

I decided on dry sanding because I wasn’t sure whether our Bosch ROS56VC would survive any large use as a wet sander. Now David went completely mad! He‘ll poison himself, many will say. I’ve read a lot of horror stories (research on the Internet, that is for ya). However, since I’ve worked as a painter for many years, I know what I’m getting into with antifouling. I’ve already removed a lot of poisonous paintwork in days and weeks of sanding. I therefore know how to protect myself so that I don’t have to die a miserable death right at the beginning of our big refit.

My precautionary measures

After we picked up our giant amount of sanding discs in the Ferreteria de Puerto Peñasco, we could start. Firstly, I chose clothes that were and will only be used for sanding antifouling. They don’t come aboard the boat and are only worn in fresh air. Those are then covered by a full-body overall with a hood, gloves, a fine dust filter mask and airtight glasses (which were probably intended as heavy-weather glasses by the previous owner of Milagros). Sanding antifouling is harmful to health and therefore self-protection is of the greatest importance.

My technical equipment for sanding antifouling

Our Bosch ROS56VC sander is connected to an industrial vacuum cleaner in order to prevent the spread of antifouling dust. This not only as protection for me, but also for all other living beings in the boatyard. After work, I immediately shower and all the material and equipment I use is cleaned every evening. The antifouling dust in the vacuum cleaner I collect in an airtight bag for disposal. At least that was the plan.

Sanding antifouling the Mexican way

If you use the right equipment altogether, antifouling dust coming from sanding antifouling is minimal. Fortunately we‘re at a boatyard in Mexico and can more or less do what we want. I wanted to know from Marc and Laura on their steel sailboat “Liquid” what to do with my biocidal leftovers. “Collect them and throw them in the trash! It’s Mexico.” Other countries, other manners. In Europe or the USA we would have had to build a plastic tent around our ship and the dust from the antifouling would have had to be disposed of as environmentally sensitive waste. Of course, we haven’t just looked at pollution, death and ruin, but have also enjoyed ourselves.

Sunset on the Cabrales boatyard in Rocky Point, Puerto Peñasco.
You have to take time to enjoy, too!

Pampering ourselves the Mexican way

We live like maggots in a piece of bacon here in Mexico. Sanding antifouling isn’t everything, we also had to enjoy life. Anyone who reads the blog regularly knows what we are talking about. Apart from sanding and working on other little projects, we also worked on our taco creations throughout the week. Sometimes we did vegetarian ones, sometimes Tacos with minced meat, sometimes we covered them with thick pieces of beef. We also indulged in one or two street food excursions and were never disappointed. We even went to a restaurant on our first anniversary!

Tiramisu love
Mmmyyyy preciiiouuuusssssss!

One step forward in our coffee game

After Captain Max from Ensenada read that we were still looking for a good French press, he immediately got us one and shipped it to us. Thank you Captain Max! What followed was an odyssey through the port area of Puerto Peñasco in search of good, high-quality ground coffee. Not even the “Kaffeehaus” had coffee to sell. Somebody understand that. Also 2-3 other shops in the area around the boatyard simply didn’t have any coffee. So we cycled once around the harbor basin and back again. Fortunately, Google Maps guided us to the “Old Port Coffee Roasters” in the completely deserted tourist zone of Puerto Peñasco. There we finally struck gold and the French Press could be inaugurated with dignity.

We dive into the hull of Milagros

Strengthened by the coffee, I returned to the easy-to-sand areas such as the keel or our rudder. I left every part of the hull that included sanding antifouling overhead aside at first. First we wanted to see what our hull looks like below its old layers of paint. Good news from this front, the fiberglass is in top condition. However, there were many small osmosis bubbles, which we were already aware of. I made good progress with my sanding project and had fun exploring the hull with my Bosch ROS56VC. I even discovered an old repair on the keel. Must have been a collision. However, this has been well repaired and is therefore no cause for concern.

Those who refuse to follow…

Then it went to overhead sanding. And the fun stopped immediately. Within a very short time I was physically and mentally exhausted. The sander got heavier and heavier, the arms weaker and weaker, and so did the mind. From one moment to the next, I made progress only half as quickly than before, because I couldn’t keep up the necessary pressure on the machine. If I tried anyway, my face was way too close to the machine. A security risk. For my face and also for my airways.

I give up!

After less than half a day, the case was clear. Under no circumstances would I be sanding antifouling overhead for days – maybe even weeks. Everyone else was right anyway. You really don’t have to do that to yourself. Annoyed, I reported my decision to Pati. She replied with a mug of coffee and something to eat. She’s the best at calming my nerves. But what now?

Sanding the hull of a Kelly Peterson 44 bluewater cruiser sailboat.
As far as I got. I’ve worked in an office for too long.

The last will be the first

Of course, we wouldn’t allow ourselves to be scared off by this first small setback. It was clear from the start that sanding antifouling would not be a piece of cake. Now it was time to find a solution to our problem. And the solution came faster than expected and will be quite interesting.

If we have not yet died from sanding, you are very welcome to support our work on the blog with a monthly contribution of your choice on Patreon! Thank you very much!


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