Boat Coating Solutions

Peeling Back The Layers Of Boat Coatings

There's usually guesswork involved, mingled with the frustration of having to choose one of the available options. At Let’s Clean, we talk to customers daily about boat restoration for removing anti-fouling paints from the bottoms of boats. Many times we are asked, "will your product Blue Bear 670AF (SOY• Strip) damage the gel coat of the hull", and the short answer is, no, not if used properly. But in an effort to help ease any frustrations with the restoration process, this article will explore some information about gel coats, other coatings on boats, and some other factors that affect restoration.

Fiberglass boats are usually made in a mould, in most cases with the fiberglass mixed with polyester resin. During this process, the coloured gel coat is applied. The gel coat can be a two part epoxy, but generally, today it is a polyester resin, the same resin used to make the hull, basically just without the fiberglass mixed in. It has colouration added to give the boat its colour. These gel coats are incredibly durable, and they serve the purpose to protect the original fiberglass hull from water damage, fresh and saltwater organisms' adherence and growth, and UV damage. Many newer boats only have this gel coat layer as the final coating, and it is buffed to give the boat a very nice glossy lustre. If you have seen a speedboat on the water that looks nice and glossy, you are looking at the gel coat polished.

Virtually all new and old boats have a gel coat. It is at this point that decisions can be made for additional coatings that can be applied based on what and how the boat will be used. We've put together a decision chart based on considerable research from manufacturers, articles, and forums with posts from users and boaters themselves.

Fiberglass HullClick here to view larger version

How you will use your boat, and how often it is in the water, will determine whether and which of these additional coatings can or must be applied to your boat. We will explain the workings of each additional coating and when you might want to apply them.

After the gel coat, the next coating that could be applied would be a barrier coat. Barrier coats are not applied to a new boat during or immediately after the manufacturing process. They are only decided on for use after a restoration of the bottom of a boat. The primary purpose of a barrier coat is to add additional water barrier protection to the gel coating and fiberglass hull.

Over time, the
 gel coat and fiberglass hull will absorb water. This absorption can create cracks and water blisters in the coating, and in the worst cases in the hull itself, if not properly maintained. The barrier coat is applied 3-4 times to help further protect a previously damaged gel coat or fiberglass hull. Barrier coats are two part epoxy based systems and are sometimes used as a primer coating (a single layer) for any boat restoration job, regardless of the integrity of the gel coat or fiberglass hull.

Photo shows blistering and cracking of the gel coat and outer layers of paint.Photo shows blistering and cracking of the gel coat and outer layers of paint.


Whether you are putting your boat in the fresh water or in sea water, next you will have to decide if the boat will require a coating of anti-fouling paint. The purpose of the anti-fouling paint is to help keep the marine animal and plant life from attaching itself to the bottom of the boat. When marine life attaches itself, it can slow the boat down considerably, add additional weight and ultimately even damage the boat. Plus it can just be a real bear of a job to clean these organisms off the boat. An anti-fouling paint is a single component coating (a single component, so no mixing by the user). It has metals (currently copper) and biocides added, and these are what discourage marine life.

Photo shows the colouration of the original gel coat and the barrier coat applied over the gel coat

Photo shows the colouration of the original gel coat and the barrier coat applied over the gel coat.


Over time, additional layers of anti-fouling paints can be added to the boat, usually each year, like putting new shingles on your roof over the existing shingles. This allows a boat owner to clean the boat surface and if in good condition, just add a new anti-fouling layer to keep the marine life at bay. Sometimes boat owners can get away with 3-6 layers total. But at some point, the additional coatings will add too much weight to the boat and must be removed in order to start with a fresh single layer.


Lastly, before the application of the barrier coat or before the anti-fouling paint, primers can be applied to help the bonding process of the primary coatings. Great care must be taken when preparing, mixing and applying gel coats, barrier coats, and anti-fouling paints, and when not done properly they can break down faster than expected, causing unforeseen problems. These primer coats can help in the process when restorers want to take extra precautions doing their own restorations.


As you can see, there are many coatings that can be applied, depending on how you use your boat. And when it comes time to do your restoration job, keep in mind that Let’s Clean Blue Bear 670AF (Soy-Strip) is a great product for removing anti-fouling paints and even barrier coats.


When used properly, Blue Bear 670AF (Soy-Strip) is designed to remove multiple layers of anti-fouling paint and possibly barrier coatings if needed, but not damage or remove the gel coat. As described above, a gel coat is an incredibly tough poly resin, the barrier coat is a semi-tough two part epoxy and the antifouling paint is a simple single component coating. So as the Blue Bear 670AF (Soy-Strip) begins to remove the coatings, it can easily remove the anti-fouling paints. In most cases, this takes between 4 to 10 hours. Then, if needed and not rinsed off, it begins to work on the barrier coat. Under the barrier coat is, of course, the gel coat, which is very tough. It would take a very long time, generally 18 hours or more, for Blue Bear 670AF (Soy-Strip) to even begin to affect a gel coat. That is far too long to leave Blue Bear 670AF (Soy-Strip) on.

It is no secret that doing restoration work on the bottom of a boat is very hard work, and it is easy and tempting to take short cuts to hurry the process. Taking the time to get correct information, and to use the right products and application methods, can save you a lot of heartache and worry, plus keep you and your boat sailing happily in the water!

Common layers of coatings for older and some newer boats

Common layers of coatings for older and some newer boats.