Like the character Jaws in the old James Bond movie, rope clutches grab hold with a ferocious bite. This month we take another look at these toothy devices and how changes in materials and design are reshaping the art of clamping down. Since our last test (see Practical Sailor March 2009 online), several manufacturers have improved their existing designs to grip better than ever. Others have unveiled completely new approaches.
Rope clutches are a great innovation that can help sailors better control the lines that lead aft to the cockpit and those that cluster around the mast base. But as with many good things, there is the risk of over-doing the benefit.
Splicing is king in any discussion of line termination. By carefully tucking cover and core back into the line, or weaving strands in laid line, and using patterns that have been perfected over time, we can create virtually full-strength terminations that will last the life of the line without maintenance.
All lines were broken once to determine approximate breaking strength without a stitched eye. A simple chain fall and load cell provided a means of pulling test samples up to 5,000-pound loads. The samples were then sewn or knotted into dog bones 6 to 8 inches long with an eye on each end, and the load was again applied until failure. This allowed the testers to compare breaking strengths with and without a stitched eye or knot. The test was broken into two parts, laboratory and field testing.
We principally looked at three means of seizing an eye without splicing-basting, round-stitching, and seizing-used alone and in combination. Round stitching is described in the accompanying main article. Here are some of the other stitching patterns we tested.
A mainsail halyard shackle needs to be as reliable as an on/off switch on a table saw. Its a one-act pony thats counted on to perform perfectly each and every time. These essential shackles fly under the radar and have become so much a part of every sailors routine that they are simply taken for granted. They terminate mainsail, mizzen, and foresail halyards aboard sailboats ranging from dinghies to mega yachts. We become so familiar with the hardware, that idiosyncrasies like a slightly bent clevis pins, damaged threads, or a misshapen stamped fork opening are tolerated.
Brass is a pretty poor marine metal. An amalgam of copper and the much less costly and corrosion-prone zinc, brass reign afloat, at least in load bearing hardware, was short lived. But when copper is alloyed with less corrosion-prone metals, the result can be quite different. And although brass and bronze sound confusingly similar, their attributes tell very different stories.
Snap shackles have become as familiar to sailors as pots and pans are to a harried chef. From dinghies to mega yachts, the function of these ubiquitous bits of hardware remains consistent. Each affords a quick and reliable means of making that all-important halyard-to-sail junction. The absolute minimalist might say that a bowline can do the same, afterall, isn't it the favored means of attaching sheets to the clew of a sail? The knots-for-snap shackles debate loses out, however, when it comes to hasty halyard swaps, not to mention the release of a loaded spinnaker guy. And even if youre not quite ready to label these shackles as essential hardware, they certainly do make life on the foredeck a whole lot easier.
For this evaluation, each shackle was visually inspected, component parts were measured, and stainless-steel alloys were noted. During this initial inspection, we tested how easy each snap shackle could be closed with one hand; we also repeatedly measured how easily the un-clipping process could be executed using a simple tension spring-test on the piston-pin versions and by using a height scale on the Tylaska push-to-release latching model. We recognize the importance of pin security under load and felt that the reluctance of a shackle pin to be easily pulled under load was, in many cases, an attribute.
When it comes to stainless steel, nothing seems more baffling than the latest array of alloys that have migrated into the marine market. Not so long ago, stainless steel was referred to as 302, 304, and 316. These differing grades of stainless varied according to chrome and nickel content and the corrosion resistance they afforded.