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: The sister beams reinforce the failing ceiling beam to easily carry the load, with capacity to scare. Rebar is embedded into the bottom surface of the sister beams where the tensile load is at its maximum. (Figure 6)
While working in my shop/converted (never to be seen by a car) garage, I noticed that the double 2×8 beam supporting my ceiling joists was sagging about 2 to 3 inches in the middle. The builder of this forty-year-old garage didn’t use full-length 2×8’s to span the 19′ width, but four 2 x 8’s nailed together with staggered butt joints. Over the years, gravity took its toll. The nail holes elongated, the butt joints opened up, and the beam sagged ominously. Continue reading →
Gelcoat blisters can be a serious problem if left unattended. At some point, your hull may need extensive repair, including gelcoat removal and epoxy barrier coats as described in Gelcoat Blisters: Diagnosis, Repair & Prevention. However, if you have isolated blisters and a manageable number to repair individually, we often recommend that you patch individual blisters and continue to use the boat until you determine the cause and extent of the problem.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 →
On a break from the Maine Boatbuilders Show in March, we visited Hodgdon Yachts, Inc. and found significant progress on their latest build, a 155′ Bruce King designed wood/epoxy ketch, named Scheherazade. This is Hodgdon Yachts’ largest wood/epoxy vessel to date. The project is roughly 60% larger than Antonisa, the 124′ sailing yacht they launched last year. Continue reading →
We recently did adhesion testing to Corian and Wilsonart surfaces with WEST SYSTEM 105 Resin and 206 Hardener at the request of a composite panel manufacturer. Corian and Wilsonart are mineral filled acrylic panels that look like granite and are often used as countertop material in kitchens and offices. Cabinetmakers and contractors typically use the panels in ½” thickness for residential applications. They are quite heavy, though not nearly as heavy as actual granite. Continue reading →
There are those who still question the longevity of an epoxy composite structure. They state that the technology is still too new to know how it will hold up long-term. Some have said that epoxy composites fail in the tropic heat; other critics have warned of the hazards of wood and freshwater. However, I’ve recently visited several boats that are living testimony to the long-term reliability of epoxy composites. Of course, careful construction and good Continue reading →
Now in their 25th year, Carrying Place, Canoe & Boatworks Limited is still producing high quality canoes, kits, plans and accessories for the discriminating paddle sport enthusiast. All of their plans have been designed or lofted by Joe Ziemba, and each design is enhanced through a special computer program. Continue reading →
Clark Eid, a research investigator for Bristol-Myers Squibb in Connecticut, has a daughter named Amanda who suffers from Rett Syndrome. Rett Syndrome strikes about one in 10,000 children, and resources for research are limited in the United States. So Clark built a kayak named Double Helix and organized Continue reading →
Paul Schreiter of Appleton, Wisconsin found the plans for this vintage speedboat in an old library book. The design is a 1936 inboard racer but powered by a 120 hp Mercruiser. Paul says, “I will go as fast as you want.” Continue reading →