Boat Wood Finishing
Refinishing your boat's wood will not only help it look better, but will help protect it from the harsh effects of the sun and salt water.
Wood on a boat is pleasing to the eye and touch, but requires some kind of finish to stand up in the marine environment. The sun will bleach it and turn it grey, and moisture in the wood will allow mildew spots to grow in the grain of the wood. To protect the wood on your boat, oil, polyurethane varnish, Cetol, or wood finishing wax can be used.
Which wood finishing product is right for teak, mahogany, or other wood on your boat? The answer depends in the end on what you like and how much work you want to do.
If you are working with new wood, all that is usually required is a light sanding and removal of sanding dust before a finish can be applied. If the wood is weathered, you will have some work to do to restore it prior to finishing. Scrubbing with a brush or abrasive pad using wood cleaners or diluted bleach will remove mildew stains and grime from the grain of the wood. A pressure washer will also work, but will remove soft fibers, raising the grain of the wood over time. Once the wood is cleaned, sand with 120 or 150 grit sandpaper to expose fresh wood. You can remove sanding dust with a vacuum cleaner or with compressed air or a tack cloth.
Oil is the traditional way to protect wood on a boat, and it makes a nice finish. It is also pretty easy to get a nice looking oil finish: just sand the wood until you are satisfied with the uniform appearance of the surface, vacuum it or use compressed air or a tack cloth to remove the sanding dust, and wipe on the oil. In the tropics, this needs to be done at least a couple of times a year.
Some oils contain wax, which makes for a smoother initial appearance and somewhat longer life. The drawback I have found is that the wax tends to trap dirt in the grain of the wood, but it also offers some waterproofing protection. I have used Watco, Amazon, West Marine brand, Daly's SeaFin, Tung oil, Linseed oil, and a few others. It takes more coats to get a good finish with some of those, but the finish also tends to last longer.
To get a real mirror finish with oil requires a lot of work. As a teenager, I worked one summer at a custom cabinetry shop, and we built an architect's desk from red oak. When it was complete, we sanded it down with 220 then 400 then 600 grit sandpaper, and then I came in every morning for 3 weeks and rubbed it down with extra fine steel wool and oil. It looked magnificent at the end, and I decided to never attempt that again!
Varnish is my favorite finish for teak or mahogany on a boat. Nothing looks nicer than well varnished wood, and it's easy to clean to boot! Achieving that finish requires multiple coats of varnish, and recoating periodically to preserve the UV protection. When possible, varnished wood should be protected from continuous exposure to the sun by canvas covers. It will last much longer and require less frequent application of new coats. When shopping for varnish and comparing brands, look for high UV resistance. If you want extra hardness for resistance to abrasion and wear, for example on stairs, cabin soles, or coamings, it can be worthwhile to get one of the two part varnishes. The best varnish products cost more money initially, but look better for longer, saving time and money in the end.
The more wood your boat has, the more important it is to keep up with maintanence on it so that it doesn't get out of hand.
Sikkens Cetol wood finish has always had superior resistance to weathering, but the original product made wood look like it had been painted with a thin coat of orange paint. The new Cetol Light and Cetol Natural Teak products produce a nice finish which is almost as clear as varnish, but withstands the tropical weather much better.
Paste type wax products such as Briwax, which is a blend of beeswax and carnauba wax, work well to seal and preserve wood. Watco makes a liquid solvent based wax which wipes on easily. Any kind of wax requires buffing to properly distribute and melt in the wax.
My take, in brief
Oil is the easiest finish to apply, but requires more frequent reapplication. Varnish looks the best, but protection from sunlight is very important to avoid the major job of stripping off cracked and yellowed varnish. Cetol has come a long way in appearance, and I would now use it on one of my boats. Wax is for furniture, not boats.