By Greg Bull – GBI Technical Advisor
Those new to the process of fairing a boat’s hull or deck are quick to mix up a batch of fairing compound, WEST SYSTEM® Epoxy with a low-density filler, and apply it to the surface, so they can start sanding right away. My experience in boat repair and construction has taught me the importance of making a fairing plan and selecting the correct materials before any epoxy is mixed.
An epoxy fairing compound should be of a consistency that can be troweled onto a surface without sagging. Add 407 Low Density or 410 Microlight filler to mixed epoxy, checking the consistency as you stir in the filler to determine if the mixture has the correct viscosity for your application.
While fairing the bottom of your boat may seem beyond your reach, it is a project that novices and experienced boaters alike can accomplish with a few simple tools and a love of a little manual labor. Most seasoned sailors would agree that a clean bottom leads to faster sailing. Sometimes it may be necessary to do more than scrub away the algae and zebra mussels, though. In the case of Adagio, 44 years of sailing was starting to ripple the bottom of the boat. Simply put, it was time to fair the bottom. Continue reading
All of the boat builders that I know have little sanding tricks that make a job go faster or do it better. Fairing a 40′ custom-built hull is an arduous task that is often accomplished with two-man teams and fairing boards. We do 90% of the work with a grinding device. Almost everyone in the business will agree that a grinder will remove a substantial amount of material quickly. The trick is controlling that removal. Continue reading
Jan Gougeon’s newest boat, currently called Project X (later christened STRINGS —Ed), is in the home stretch to completion, and Jan is addressing the fine tweaks of coaming and fairing by using a special fairing technique. Continue reading
Above: Surface prep testing using ASTM D3359. This calls for a single-edged razor blade to score a pattern through the coating. Applying a strip of masking tape diagonally across the pattern, then pulling it slowly back over itself will reveal the relative degree of adhesion to the substrate or primer.
Before you begin a project, it is a good idea to consider all of your options. Information about products or methods you may want to use is often available on product labels, from manufacturers, or your own experience. However, many times the information you need to make good choices is just not available. Then your best option is to test. In our most recent sailboat renovation, we had to figure out what to test for and how to do it. Continue reading
Above: For wet sanding epoxy, a typical grit sequence for smoothing an already flat surface would be 80 or 100 grit, then 150 or 180 grit, and finally 220 grit.
Wet sanding with waterproof sandpaper is often the best approach to sanding cured epoxy. Wet sanding epoxy emoves any amine blush while you sand, reduces clogging of the sandpaper, and reduces dust and exposure to partially cured epoxy. It lets your sandpaper go farther and provides a visual clue that everything is properly sanded. However, when working with bare wood or wood that cannot get wet, you will need to dry sand. Continue reading
I recently ran out of sandpaper for my 5″ diameter random orbital sander, and needed only a few more sanding disks to finish the project. While my sander is equipped for the hook-and-loop style sanding disks, I had only PSA (pressure sensitive adhesive) style sanding disks. These did not stick well to the pad on the sander, and within a minute or two they would fly off, leaving me frustrated. I finished my project by gluing the PSA disks to worn out hook-and-loop disks with contact cement. This actually worked quite well. Continue reading
Dragging your catamaran over sandy beaches can abrade away material on the bottom of the hull, thereby flattening the sectional shape. Usually this area will extend 4 or 5 feet each way of the hull’s mid-section. You need to fix it so it doesn’t wear through, and to maintain optimum design performance. Continue reading
My son Matt and I recently built a small stitch-and-glue boat. While fairing the bottom we discovered that hacksaw blades can be modified and used for fairing.
The buildup of fiberglass tape along the chine and keel had caused a low spot in the hull all along the edge of the fiberglass buildup. Filling the low spot with low-density filler was easy, but sanding the cured epoxy with sanding boards was slow work. Experimenting with a new hacksaw blade, we found it easily cut through the low-density filler and occasional high spots in the fiberglass. Continue reading