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Types of marine sealants and their application

When we put some equipment on the yacht, it is naturally a desire that their connection be waterproof. For many centuries seamen used pine tar for these purposes, but with all its indisputable waterproof qualities, it has one drawback - it gets dirty very much. Therefore, at some point of the last century, for "yachting" purposes tar was replaced with more civilized compounds based on petroleum products. Of this number, perhaps, the most popular was the dolphinite (Dolfinite). It looked and looked like coconut oil in its properties. By the way, it can be found now and its use is appropriate where there is no need for adhesion.

The main problem of compositions based on petroleum products is that they have the property of drying out and eventually lose their properties over time. Therefore now they were replaced by polymers - chemical compounds, which lack such a lack. The modern sealant, being properly applied and mechanically intact, retains its water resistance for the entire life of the yacht.

So why do leaks occur? The main cause is mechanical damage, which is manifested by tearing off the sealant from the substrate under load due to insufficient stiffness or poor contact. Reinstalling in such cases helps for a short time and to find a way out in this situation I suggest you read the tips at the end of the article.

A huge selection of sealants, available today for sale, causes nostalgia for those times when the only option for "marine" sealant was tar. But do not get upset - the choice of the desired sealant is much easier than it may seem. Manufacturing and adhesive tube filling companies such as cedesa.co.uk ship adhesive globally. The fact is that the "marine" sealants are divided into three groups. And you just need to understand which of them is most suitable for a particular task, and which one is not suitable at all and on this the entire choice can be considered finished.

Polysulphide. You can and should put anything on them. Polysulfide sealant is an artificial rubber with excellent adhesive properties. They are, perhaps, the most versatile of the "marine" sealants. With load and temperature deformations, they allow moving adjacent elements, while not breaking down and retaining adhesion to both surfaces. They even have an adhesion to the oily surface of the teak and do not break down when aggressive liquids take care of the teak, being the best choice for laying the teak bars. They are perfectly suited for sealing gaps in the rack casing, since after polymerization they can be sanded and dyed. That mastic black that looks between the plank teak deck - definitely is a polysulfide sealant.

You should be warned - polysulphides can not be used to install plastic elements such as hatches, portholes or deck equipment. These sealants contain a solvent from which acrylic, polycarbonate, ABS and PVC - plastics become fragile and crack. This can be done only if you are absolutely sure that this element is based on epoxy, nylon or dolines. All below the waterline fittings also fall into this group and if you have any doubts, it is better to choose a different type of sealant.

Polyurethane. Note that polyurethanes relate to glues rather than sealants. What is put on them, it will be difficult to further separate without damage, so we do not recommend putting anything on them that might require disassembly in the future. They have excellent properties for connections such as body-keel and hull-deck and good for fitting end-to-end fittings or private laths. You should not, however, put on the polyurethane sealant teak bars, as the means for tic care destroy it. As in the case of polysulphide, acrylics, polycarbonates, ABS and PVC should not be applied to polyurethane sealants.

Silicone. When you choose a silicone as a sealant to create a gasket, then you have guessed its purpose. Silicone will be the best option for joints that are subject to periodic disassembly. Its high insulation properties are useful for the installation of elements from dissimilar metals, for example, stainless coils on an aluminum mast. And most importantly - this is the only "marine" sealant, which you can safely put plastics. For all this, silicone can not be used below the waterline. And since the watertightness of the connection with silicone depends to a large extent on the degree of its compression with fasteners, it is not suitable for installing practical items on the deck of a sandwich (three-layer) structure.