| Vol 1 - Issue 5 | January 1997 |
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Knowing the Ropes What's the difference? By Mark Michealsen |
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One of the items that needs to be replaced regularly on your boat are the
lines (ropes) which control the equipment. When replacing your ropes you
need to know
a couple of things before spending your hard earned money.
#1 You get what you pay for. We have 1/4" line for $.19 per foot! It's cheap, literally. Don't get me wrong, it does the job, but is like the "standard sailboat line" you will buy at any marine harware store. #2 Decide what kind of sailing you do and how often you sail. If you only cruise the boat then you can buy intermediate priced line that is very comfortable on your hands in a variety of colors which is easier on your crew for identification purposes. We suggest "spun dacron" called Samson trophy braid. For years it has been called "the fuzzy stuff" for its soft cover. No one makes it the same way Samson does and the price is quite reasonable. Trophy braid will do the job for just about every control line and sheet on the boat for the cruiser. #3 Every spot on the boat requires a different type of line for the sailor interested in performance or durability. Several factors should be considered. #4 Do you want it to be light or durable? You can not have both!. If someone tells you otherwise, they are wrong. High performance control lines and equipment. Basic rules- The smaller the diameter of line (same core and case) the lighter it is. Strength/construction. The strongest material in linear test is "technora". This is similar to kevlar but is not brittle. Technora is 1.4X the strength of kevlar at 68% the specific gravity. Anyone interested in performance no longer uses kevlar on anything. Every single America's Cup boat currently competing virtually uses Technora on every line. Spectra (a trade name for dyneema) is a very light and very strong core material for the high performance boat. Spectra has infinite stretch (creep) but is not very elastic relative to its diameter. A line which claims to be "spectra cored" should be checked for its spectra/poly blend ratio. All that means is how much spectra is in the core versus polypro or dacron. A 75% ration should be the minimum. Most spectra control lines use a polyester or dacron case to give longevity to the line. This also means it soaks up water like a sponge! You should look for a polypropalene case. Several manufacturers offer this combination: Yale, Samson, and Marlow are the only manufacturers in the US tooffer this combination of strength and light weight. Blending spectra and technora: in a phrase, BAD IDEA! Why? The spectra material creeps eternally (until it breaks) leaving the technora to bare 100% of the load. If the line were pure technora or pure spectra all of the fibers would "creep" at the same pace leaving all of the diameter to handle the load. It has been tried and proven to be the least logical way to build a rope. #1 Does it need to be strong? Maybe not! The main halyard and jib halyard on most catamarans do not bare the load. The halyard is "locked" by the use of a hook or wire. This does not mean you should buy cheap rope to use on the halyard. It means you should buy "PRESTRETCH". If you have ever tried to pull up a sticky halyard with stretchy rope you know how hard it is on your hands! "Marlow pre-stretch" is the best line out there and comes in five different colors. The same characteristics are important for trampoline lacing. It does not need to be super strong, but it should be pre-stretched to save you the effort of retightening the tramp every other week. Marlow prestretch has a very tough and tightly bound case on it to stop premature wear on the line. Cheap line with a loose case will fall apart quickly on you. If the line is soft and supple, it's the wrong line... #2 Know the facts about your load requirements before you go to buy your line. The improper use or undersizing of lines on your boat can spell disaster! Your trapeze line keep you and your crew attatched to the boat. Buy pre-stretch! Kevlar is brittle and snaps when pulled over small pulleys. Use spectra or technora in the appropriate sizes. Your jib halyard may bare 100% of the mainsheet load if you run a race boat with an internal halyard. This can translate to 1200lbs of static load and impulse loads to 2000lbs! #3 Ask a knowledgable person to assist you in selcting the right line for your needs. The first question to ask is "Do you sail catamarans". If the answer is NO, keep looking for a knowledgable salesperson. Remember, you get what you pay for... Mark Michealsen sailcenter@aol.com Back to Features |