Varnish is the clear finish that is used as a finish on boats and other wooden crafts. It is a hard film or coating that protects the wood that is underneath from being scratched or damaged. Varnish is usually a mixture of three components, which are resin, drying oil and thinner. These finishes typically have a gloss or shine to the finished wood. You can get varnish in a matte, flat or semi-gloss finish as well, but these finishes are not as popular.
Varnish naturally is transparent or has very limited color to it. If you want a darker look than what is presently there, add a color stain prior to applying the varnish. There are a few manufacturers that do combine their stains and varnishes into one product, but it is recommended that you do these steps separately.
Marine varnish has a different function than other types of varnish. A marine varnish has to be extremely flexible. It needs to bend and move with the movement of the boat wood. Boats and ships have stretching factors and there is also a compression factor. Marine varnish needs to be able to move with the wood without losing its bond or hold on the wood. Some Manufacturers use extra oil in the production of their marine varnishes. This means that the varnish is more pliable and will flex more than your standard marine varnishes.
If you were to use a regular wood varnish, it would crack and flake off each time the boat went through its swelling and shrinking process. Once that happens, it leaves the exposed wood wide open to be damages by the water and other natural elements. Regular varnishes are not intended to take on the difficult task of sealing things like a boat or ship.
There are several brands of marine varnish available on the market, but you should do extensive research on each one before deciding on a single brand. Read the product information and the customer reviews to get an overall idea if that is the choice for you. The last thing you want is for something as important as your boat to be damaged, due to a poor choice of marine varnish.