Into the Wind
by Jeff Williams
http://skycraft.net

Ropes and Stuff

I couldn't help but watch the fellow in the hardware store trying to make a decision on what rope to buy to anchor his motorboat with. The young store clerk didn't have much advice for him; he could only tell him the difference in price between the different types of rope. Reluctantly, he chose the cheaper type.

I'm all for saving money. After all, the wind is free and everything else should be too. Unfortunately, the law of 'you get what you pay for' prevails. Good rope doesn't cost that much, and properly selected, works much better than the cheapest alternative.

During the age of sail, ropes were made of natural fibres like hemp or sisal. The strands of fibre were twisted into a yarn. Typically, three yarns would be twisted together in the opposite direction to form a rope. Today, ropes are still constructed this way, using nylon, dacron or polypropylene. Three-strand rope is easy to splice into a loop, and has some stretch, which is useful in some applications. Surprisingly, hemp has very similar stretch and strength characteristics to dacron. Unfortunately, it weakens quickly from weathering and rot.

Double braid rope has become the more common choice of rope. Like the name suggests, it consists of a braided inner core, and a braided outer 'jacket'. The strength of the rope is divided between the two braids. This rope can also be spliced, and holds knots well. It is used almost exclusively on sailboat's rigging because it runs smoothly through pulleys and works well in the different types of cleats. Rope that you use for tying up the boat should have some stretch in it so that shock loads on the mooring cleats are dampened. Here, nylon is the best choice. It is strong, has some stretch, is resistant to the weather, and can even be bought in custom colours to match your boat. For a little extra money, you can buy them prepackaged with a loop spliced into one end for looping through a cleat. Either double braid or three strand rope works well, with the three strand having a little more stretch.

The most common rope for the rigging on a sailboat is made of dacron. It is prestretched as it is braided so that it won't stretch while you're sailing, Double braid dacron is available in a huge selection of colours and patterns, so that you can colour code the control lines on your boat. (It's much easier to ask a new crewmember to pull on the red rope, rather than saying, 'tension the vang’.) Incidentally, if your spring-loaded cam cleats no longer seem to be holding the rope under tension, try some new rope first. This will often solve the problem, and cost much less than new cleats. Polypropylene is the material to use if you need the rope to float. The three strand yellow stuff from the hardware store is made of polypropylene. It is also ugly and doesn't hold a knot. This stuff comes in different grades, including a single braid construction that has a soft feel like nylon or dacron. I use it for some of the rigging on my own dinghy because it doesn't soak up water in the bottom of the bilge. If you’ve ever had a wet dacron mainsheet that wouldn’t feed out the blocks quickly enough in a gust, you can see the value in using this rope. Polypropylene is more vulnerable to the sun's UV rays than nylon or dacron. Try to store this type of rope out of the sun.

Finally, there's rope for high-tension applications where minimum stretch is required, such as halyards for raising the sails. Stainless steel wire can be used to replace rope, but it's important to use the right type of wire. For halyards, where the wire must go over a pulley, a flexible wire is required. This is accomplished by using cable made up of fine wires. A common choice is 7 x 19 cable, which is made up of 7 strands with 19 wires in each strand. The stays and shrouds that hold up the mast don't have to be flexible, so they are made of 1 x 19 cable, which is one strand made up of 19 thicker wires. Although it's not usually seen around here, synthetics such as kevlar, spectra, and carbon fibre can be used to replace dacron and stainless steel. These materials are usually used only on racing boats where minimum stretch and reducing weight are more important than the higher cost.

Using the right type and size of rope for the job will probably cost a little more, but you will be repaid with rigging that works better and lasts longer.

Jeff Williams
http://skycraft.net