Theres little debate over the adhesive quality and toughness of epoxy resin-just look at where its being used. We hear about its presence in crucial structures such as aircraft wings, race car bodies and high-end custom racing yachts. But it takes a little familiarity with engineering lingo to help us understand why epoxy trumps its ester relatives.
In addition to all of that lovely salt, seawater is very hard, nearly saturated with calcium. All it needs is something to react with (uric acid in the head) or localized overheating (engine) to create concrete-like incrustations. Sometimes mechanical removal is possible; a favorite cruiser ritual involves hauling out the sanitation hoses and beating them on concrete to remove internal scale build-up. Heat exchangers can be reamed out with a rod, but most engine and plumbing systems are inaccessible without considerable disassembly.
Although through-bolts may be the gold standard for strength and security, sometimes drilling a hole isn't practical, or exposes foam or balsa core to water intrusion. Mounting a sump-pump to the side of the hull, attaching electrical components when the other side is either inaccessible or exposed, mounting an air conditioner on the bridge deck of a catamaran, or adding solar panels to a hard top are just a few examples of situations where a surface mounting is needed.
For maximum maneuverability, the control lines-one port, one starboard-should attach at the widest part of the boat. This maximizes leverage and places the effort close to the center pivot point. On a catamaran, closer to the transom works because of the wide beam, but for monohulls, attaching near the pivot point at the keel will be more responsive. For maximum responsiveness, the drogue should be as close to the transom as practical-this results in more responsive steering and minimal drag. We found the best compromise to be around 65-80 percent of the way aft, where there is still enough beam, but less risk of the control lines fouling.
Every fall, as the hauled-out boats are sardined into boatyards, a walking tour reveals the casualties from the underwater war. Saildrives are deeply pitted and shedding paint. Bottom paint is burned near seacocks. Folding props no longer fold. Most often, these losses are blamed on the zinc anodes-or lack of them.
The anodes were cleaned, weighed, and installed on 2-foot lengths of 3/4-inch, copper pipe (type M), which were also weighed. We hung the samples between slips in the mid-Chesapeake Bay near Rockhold Creek for one year, cleaning quarterly to mimic light use. At the end of the test period, the samples were cleaned with a plastic scraper and scrub brush, and their interiors were scrubbed with a snugly fitted multi-knotted rope. Testers gave them a light acid cleaning to loosen barnacle residue and scrubbed them again before weighing them. We also measured potential driving force and current for each anode before and after exposure. Salinity at the test site varied from brackish to seawater salty. We will be testing in full-strength salt water for a followup article.
Many years ago, one of our editors had an old wooden boat with lovely wooden handrails just inside the companionway that his sailing partner decided could use new varnish. The original coat, which was peeling around the base and worn where hands had gripped it, was sanded smooth and meticulously coated with varnish. Subsequent coats were applied according to the process that had served well for years-varnish, scuff, wipe, varnish, scuff, wipe . . . repeat.
We recently launched a new evaluation of marine adhesives and sealants. There is no single caulk that works in all of these cases, so its impossible to declare a single Best Choice adhesive, but we decided to at least put some numbers on paper to guide you in your choices.
Our test focused primarily on the small-wire connections tensile strength, with and without solder, but we also looked at their durability under tough environmental conditions. We tested the pull-out strength without solder and the pull-out strength of soldered connections at 400 degrees by heating the connections in an oven to simulate overheating conditions. We tested fatigue by spinning a 6-inch length of splice wire at 650 RPM in a simple device that we called the wire-fatigue whirligig. Finally, testers soaked all samples for four months in salt water to accelerate corrosion, and then, we repeated the fatigue test.
For many seasonal sailors, the winterizing routine is already well underway. But there are more than a few diehard sailors in the mid-Atlantic regions, on the West Coast, and even in New England, who plan to spend all or part of the snowy season afloat. Some, we daresay, look forward to the quiet of winter. If youre toying with the idea of keeping your boat in the water during the winter, heres a short rundown on some of the more important steps to take.