Airboaters have a unique problem. They need their boats to go fast and easy on water, marsh plants, roots, and dry land. That means their airboat hulls needs to be both very slick in water, but also very slick and durable on land. Asking a boat hull to endure the punishment of scraping along sandy beaches, endless sawgrass marshes, and grass fields and THEN slip efficiently through the water, day after day, weekend after weekend, is asking a lot. If you’re not runnin’ with polymer on your airboat, chances are you’ve got some sort of friction-reducing slick bottom paint on your hull. I am going to describe how these slippery coatings work, as well as how best to utilize them.
There are a variety of liquid hull coatings on the market. Ideally the best liquid hull coating would be one that is tough, slick, and long lasting. I talked to Glenn Fichter of Southern Enterprises, one of the premiere custom airboat builders working today, and asked him “What properties would the ideal liquid hull coating need to have for you and your customers?” His answer was simply “Needs to be slick, and adhere well to the bottom.” Let’s focus on adhesion first.
Two-part epoxy systems are known for their toughness, due to a high cross-linked density and excellent adhesion to a variety of substrates. As a result, the best liquid hull coatings are based on a two part epoxy system. The high cross-linked density factor makes the coating itself resistant to scrapes, gouges, and abrasion, while the adhesion factor prevents the coating from coming off, or “delaminating”, from the substrate to which it is applied.
Most of the epoxy systems used in airboating use either a primer followed by a friction-reducing topcoat, or skip the primer layer altogether and just build up multiple layers of friction-reducing topcoat. The advantage to putting down a primer layer first, before the topcoat layer, is that the primer is designed to grip the substrate tenaciously while providing the optimum surface for a topcoat to be applied. If the primer layer is allowed to cure properly, before the addition of the topcoat, the primer layer will provide an added layer of durability and protection to the overall coating system.
One of the most crucial elements to getting a hard, durable coating is allowing each layer of coating to properly cure. Notice I said cure, not dry. Dry means you can touch it with your finger, and then pull your finger away and there will be no coating on it. Cure means drying for enough time to allow the exothermic, or “heat producing” chemical reaction to take place, as well as allowing all the liquid components within the epoxy to evaporate. Only when that chemical reaction is finished, and the liquid component is driven off, can the coating be considered fully cured. Many manufacturers state that there is a window of time when the first primer layer is still “tacky” when you can add a topcoat. This may be true, but in most cases you are sacrificing a potentially long functional coating life for a quicker turnaround. Remember, the ideal liquid hull coating is one that is slippery, durable, and long-lasting. I know you want to get your boat back on the water where it belongs, but if you allow each layer of coating to fully cure, you will have better adhesion, and a stronger and more durable coating.
Now for the fun stuff – the fast and slippery topcoat that allows airboats to go faster, use less fuel and slip over hard surfaces and water plants. Silicone has great lubricating and slip-producing properties. Silicone-based friction reducing coatings come in two distinct styles, “migratory” and “non-migratory”. In the more common migratory silicone epoxies, the silicone exists only in a thin layer on the surface of the coating. In other words, during the curing phase, the silicone migrates or “blooms” to the surface of the coating, where it lays on the surface of the coating, exposing its slippery properties to reduce friction. It works for a short time, until the silicone is all gone. Once the silicone is gone, so is the slippery nature of the coating. The loss of the silicone layer also compromises the cross-linked density, which drastically reduces the durability of the coating. Therefore, with a migratory silicone coating, the more you use your boat, the faster your coating disappears.
On the other hand, in a non-migratory silicone epoxy, the silicone molecules do not just sit on the surface of the epoxy. Rather, the slippery silicone molecules are embedded equally throughout the matrix of coating. The non-migratory silicone is much less common, probably because the chemistry is more advanced and is difficult to produce. That is unfortunate because non-migratory silicone is much more effective. Even if the coating gets scratched or abraded, its slippery properties do not diminish because the silicone exists equally throughout the entire thickness of the coating. As long as there is coating on the hull, you still have a slippery surface working for you.
In talking with airboaters, it seems that a general lack of durability is the major complaint with liquid hull coatings. Freshly applied coatings are super-slick at first, but then quickly lose their slippery properties with use. In general, to avoid poor performance, apply a high quality primer that has been enhanced with silicone, allow it to fully cure, and then apply a high quality topcoat that has non-migratory silicone embedded throughout the matrix of the epoxy. If you’re not sure, just call your liquid hull coating manufacturer and get the facts.
When properly applied, liquid hull coatings help prevent corrosion, offer abrasion resistance, and greatly decrease the amount of friction in both water and on land. Friction reduction greatly improves the speed, fuel efficiency, and functional life of your airboat. Dollar for dollar, a high quality hull coating is the least expensive way to improve the overall performance of your airboat.
Wearlon® technology addresses both durability and slickness by embedding non-migratory silicone throughout the matrix of both the primer and the topcoat layer. This dual layer system provides you with a slick bottom that lasts longer and outperforms other coatings.