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Bedding hardware on a boat is one of the most important things.Heavy hardware which is under cycling loads, such as cleats, has to be bedded regularly. To make the task easier, one makes use of sealants. Most often you want a tough and strong sealant to join two surfaces such as a through-hull and the hull or a cleat and the foredeck, on a boat. The sealant should have reasonable elasticity so that it can stretch in case of load if the hardware shifts, it does not get detached the breaks the seal. There are six major classes of sealants used on a boat. These are listed below: 1. Polyurethane-based Sealants: They are ideally adhesives with properties of a sealant. They offer very strong and permanent adhesion strength, thus allowing them to be used both under and above the waterline.Commonly found sealants in marine chandleries, 3M 5200, is typically for all targets and used as a permanent adhesive but should not be used on boats for the most part. As 3M 5200 has a very high bonding strength, it can often harm the gel-coat when you try to take out hardware bedded with it. 2. Polysulfide-based sealants: If you are looking for general purpose sealants for marine use, poly sulfide sealants are the best. They are more elastic and flexible and not as hostilely adhesive as polyurethane-based sealants. Like the polyurethane sealants, they can be used both below and above the waterline and are superior to polyurethane-based sealants for hardware that has to be re-bedded more often.These sealants are best for bedding wooden items, like rub-rails and cockpit coamings, since it glues nicely to teak. 3. Silicone-based sealants: These aren’t adhesive basically. They’re really washer materials, and require a minimum thickness and be kept under firmness to work efficiently. Silicone-based sealants can be used only abovethewaterline applications.Dow 795 is often recommended for bedding ports since it is a structural adhesive. 4. Butyl tape: It is one of the most multipurpose sealants one can use on a boat. It has the highest elasticity out of any of the sealants, but, it has the poorest adhesion and tensile strength. One major advantage of butyl tape is the working life. This makes it perfect for bedding things like genoa fair lead tracks and traveller. The lower physical strength of butyl tape is not a problem generally as many fasteners are used on these tracks. 5. 3M 4000 UV: Well suited for plastics,3M 4000 UV is a polyether based sealant.It should not be used below the waterline. It gets cured up completely in 24 hours and is tack free in less than half-an-hour. 6. BoatLife’s Life Seal: This is a fusion of silicone and polyurethane sealant. Thus it is not as durable as polyurethane, but is a better bonding agent for bedding compound than a pure silicone material. However, it has many of the adulteration problems that are present in silicone based sealant. Find high quality rubber products at KV Enterprises, the distributor of natural rubber beadings, epdm & glass rubber beadings, adhesive& silicone sealant for automotive industry at Coimbatore, India.
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