Annual Inspection and Servicing a Mast
Mast maintenance begins every time you return to port. Washing down your mast after each outing will help prevent corrosion before it starts. Thoroughly rinsing the lower sections of the mast and boom from your salty adventures will save you headaches down the road. Be careful not to use harsh or abrasive cleaners or scrubbers.
While cleaning the spars, keep an eye out for signs of rust or wear on your hardware, corrosion on your spar, and chafing on your lines. Pay particular attention to areas where stainless screws insert into an aluminum mast as they are the most common points of corrosion and the earlier you catch it the easier it will be to maintain. Corrosion manifests itself as bubbles or blisters under paint; and darker, chalky areas on bare anodized aluminum. Pitting is a sure sign that corrosion is taking place and repairs are needed.
It is a good idea to go up the mast annually for a thorough inspection; some prefer every six months depending on your sailing environment and style. Look for signs of corrosion, small cracks, paint chipping, or any sings of damage to the mast, boom or spreaders. Inspect everywhere that hardware is attached to the mast. Remove the spreader boots to thoroughly inspect the spreader tips. Inspect the condition of the spreader bases, tangs, sheaves, cotter pins, and look for signs of chafing. It’s a good idea to test your electronics before going up the mast as well so you can replace any bulbs that are out or that pesky missing Windex tab. Rusted screws should be replaced. Paying attention to the little details is what this inspection is all about.
Preventing corrosion largely begins with the installation process and if you are the second or third owner of your boat you are most likely inheriting something someone else installed and maintained – or didn’t maintain. With your annual inspection you will be able to catch small issues before they become big projects.
Corrosion on a spar is primarily a result of dissimilar metals being in contact. To combat this, whenever installing hardware on a spar use Delrin washers to isolate the hardware from the mast. Delrin is preferable over nylon and polypropylene due to its UV resistance. Apply Lanocote or Teff Gel to the hardware and fasteners. Lanocote or Teff Gel should be used on any parts that you would like to take apart one day as it will create a barrier between the aluminum of the mast and stainless screws used for installation, preventing dissimilar metal corrosion.
Inevitably you will find some areas showing signs of corrosion and this is where the fun starts.
Anodizing aluminum results in an incredibly hard, corrosion-resistant surface. If your mast is a natural silver aluminum color, it is probably anodized. Unfortunately, once the anodized coating is compromised, corrosion will take place. There are various clear-coat kits on the market to protect a repaired area on an anodized mast, but the clear coating does not last as long as a high-quality paint finish, and the repair is often visible. For these reasons, painting of the affected area is recommended. Sometimes the spot repair can be hidden using a paint stripe or design.
If your mast is painted already, then the repair is easier to hide. In either case, the corrosion must be removed, filled, and the affected area must be etched, primed, and protected.
Begin the repair by removing the hardware at the site of corrosion. Sand the affected area in circular motions to remove the corrosion and smooth out the surface. Use a brass wire brush to thoroughly clean any pitted areas. You want clean, bright aluminum, not dark or dull. Corrosion commonly appears as a white dusty powder, and you want to make sure you have removed it all.
Apply an acid etching solution and rinse with fresh water, following the instructions of the etching kit which is usually a 2-step process. A popular choice is Alodine Alumaprep, also used in the aviation community. There are other products on the market as well. Use a 2-part structural epoxy filler to fill any dimples and voids. Smooth out the surface and use a fairing filler if needed.
Prime and paint the area using a high-quality 2-component linear polyurethane paint, such as Awl-Grip, following the paint manufacturer’s instructions and recommendations for painting bare aluminum.
After completing the painting process, you’ll have to re-tap the screw holes and re-install the hardware. Remember to use Delrin washers and Lanacote or Teff Gel. You can spot repair any corrosion as it surfaces to prevent further corrosion, but it is hard to make the repairs invisible. For excessive or wide-spread corrosion, removing the mast from the boat might be needed.
Stay tuned and we will discuss the process of un-stepping, repairing and re-stepping a mast.