View non-flash version
Understanding Rope (continued) Rope, in use, must be tied, fas- tened or spliced in some manner, and in every case the knot, splice or bend then becomes the weakest place in the rope—the point where the breaking/tensile strength is at its lowest. Therefore, if the "test" used does not employ a "weak point," i.e.—jointure, knot or splice, the published result is not a true example of how the rope will per- form in service. Listed below are some of the more common variables, as well as men- tion of factors that may cause wide variation in test results. 1. A manufacturer may conduct numerous tests, but publish only the test that shows the highest strength. Reputable companies will conduct multiple tests, and their advertised strength will be an aver- age of the highest and lowest break or tensile strength. 2. Some manufacturers, in an ef- fort to straddle issues of strength, will distort data with a variance to the published strength, i.e.—+ /- 5 percent or +/-10 percent. 3. Another variable the consumer must be aware of is the actual point testing from which a determination is made as to rope failure, i.e—the point where the rope breaks in two, or one-strand breaks. The company with high integrity will established rope failure at the point where one strand breaks, which is also the point that the rope ceases to be a safe, usable tool. It is possible to continue test procedure with two remaining strands intact to obtain higher readings. 4. Factors such as conditioning of rope before testing, i.e.—tempera- ture and humidity control, whether the rope is wet, or dry, are variables that can influence test results. 5. The consumer should always be aware that all nylons, polyesters and polypropylenes are not the same. One major synthetic fiber producer markets over 40 grades of nylon and 75 grades of polyester. The qualities or raw material vary from manufac- turer to manufacturer, application to application. 6. A sixth variable is rope con- struction. Normal stated figures are on regular or standard construction. Ropes with a loose twist or softer construction will be lighter and stronger than ropes with harder twists, but will not wear as well and resist abrasion as well. When in doubt as to the construction quali- ties of the rope he is buying, the consumer should determine the ex- act requirements needed for the rope he will use and then make sure that the manufacturers published specifications meet that need. 7. A final variable is that the buyer should understand that a manufacturer published breaking strengths/tensile strengths are based on new rope specimens only. Once a rope is used those strengths are not reliable. Working loads are stated, in a majority of cases as a percentage of breaking/tensile strength, i.e.—5 to 1 or 20 percent, 10 to 1 or 10 per- cent. More and more often in to- day's markets, the manufacturer will not publish working load figures and percentages unless he knows and understands the exact require- ments of the job to be done. With- out all the facts, working load esti- mates are often an exercise in futili- ty. In closing, I would like to caution the buyer and user of ropes to know his supplier, or his supplier's source. I'm proud to be able to state that my company, Columbian Rope Compa- ny, had never resorted to distorted or questionable specifications. I be- lieve the same can be said about the majority of U.S. rope manufactur- ers, large and small. But let the buyer beware, there are manufacturers who do not test their ropes, and simply use competi- tors data for their own purposes. It boils down to one simple fact. When purchasing rope, a reputation for quality, a history of product integri- ty and a record of standing behind its products and the dealers who sell them are the buyer's main safeguard against false statistics and shoddy merchandise. COLUMBIAN ROPE COMPANY P.O. Box 270 Guntown, MS 38849 Phone: 601-348-2241 in MS 800-821-4391 Other Circle 101 on Reader Service Card The M.S. Europa, seen here on the Weser River in West Germany, is the first passenger vessel to be propelled by Schottel Pump-Jets. Schottel Pump-Jets Allow Passenger Boat To Operate Even In Shallow Water Because low water levels fre- quently cause major problems for vessels navigating on inland water- ways, the West German firm of Schottel developed a new propul- sion concept, the Schottel Pump- Jet, which provides propulsion pow- er even in shallow waters. After extensive tests had been conducted on the Rhine with a simi- lar passenger vessel, two Schottel Pump-Jets, type SPJ 55, were in- stalled on the passenger vessel M.S. Europa, built by Lux-Werft ship- yard in West Germany. The Pump-Jet is integrated into the bottom of the vessel and con- sists of a semi-axial centrifugal SEALED BID SALE! OFFSHORE PARTY BOAT The RANGER V offshore party boat is equipped with twin screws, diesel power, flush deck, modified "V" bottom and all welded aluminum throughout. Dimensions are 117.6' long by 25' wide by 6.9' deep. Detroit Mdl. 16-V-149 engines rated at 2,200 HP with estimated speed of 18 knots. STEEL DIESEL PUSHBOAT The CAPTAIN JOHN H. PALMER steel diesel pushboat equipped with twin screws, diesel power, flush decks, 3-tier deck- house, split level pilothouse. Dimensions are 102' long by 35' wide by 9' deep. GM Mdl. 12-645E2 engines rated at 1,500 BHP. Vessels are located in Sabine Pass area, Texas. Inspections will be conducted by appointment only throughout January, 1989. Secured Party reserves the right to accept or reject bids and to waive informalities. To be sold "AS IS" and "WITH ALL FAULTS." Sealed Bids will be received up to 1:00 p.m. on Feb. 2, 1989, at which time they will be opened. Contact PMI for Information/Bid Package at (713) 691-4401 PLANT & MACHINERY INC. 7 AUCTIONEERS • LIQUIDATORS APPRAISERS REAL ESTATE BROKERS R O. Box 24010 • Houston, TX 77229 FAX (713) 672-7905 • TELEX #775572 (PMI HOU) ENGINEERING SENIOR PORT ENGINEER MARITRANS OPERATING PARTNERS LP. has an immediate employment opportunity for a "hands- on" Port Engineer with at least 8 years marine engineering experience. Dedicated to the application of innovative technology and sound engineering practices, MARITRANS is the nation's leading in- dependent marine transporter of petroleum products. We offer challenge and responsibility to a results-oriented, self-starting professional. Our Port Engineers serve a key role in directing assigned maintenance and repair projects, managing vessel engineering and maintenance personnel, and applying ABS and USCG regulations. This position reports to the M&R Manager at our Eastern Fleet Center in Philadelphia, PA. Up to 50% travel is required. The ideal candidate should be a licensed engineer with a BS Degree in Marine Engineering or equivalent experience in: Tug & Barge Industry Hull & Machinery Maintenance & Repair Diverse Fleet & Equipment Management By Objectives Budgeting & Expense Control Computer Applications We are proud to offer our employees a competitive total cash compensation package along with an employee benefits program that is among the best in the industry. Relocation assistance is negotiable. Please send us your resume and salary history if you'd like to confidentially explore this opportuni- ty. Qualified candidates will be contacted immediately. Senior Port Engineer MARITRANS GP INC. Three Parkway, 14th Floor, Philadelphia, PA 19102 N\ MARITRANS Equal Opportunity Employer M/F/H/V MARITRANS maintains a policy of zero tolerance of the possession or use of alcohol and/or illicit drugs aboard its vessels. 54 Circle 180 on Reader Service Card Maritime Reporter/Engineering News
