Rope Work #1

By James L. Matews
Master, H.B.M.S. Richmond

General Introduction;

A. Rope work is essential in any aspect of work at sea. This is a given,
as well as being useful in many other pursuits as well. A thorough
understanding of rope work will be required by all hands of the H.B.M.S.
Richmond including the Marine Detachment. This Lesson Plan, Rope Work
#1, is therefore intended to apply to all hands aboard Richmond as well
as the whole Company of Royal Marines assigned. NOTE: Rope other than period correct types are covered herein due to the Ship's Company being aboard host vessels having modern rope types present, even though the vessel may be a replica of our period . Knowledge of these types are important as we may have to interact with them, however, all rope and lines belonging to the Ship's Company will be period correct consisting of either Manila or Sisal of natural fibers.

B. Common sense is often a poor substitute for real knowledge, and
therefore "common sense" can be dangerous in the respect that you do not
understand the basic uses and kinds of rope.

1. --A heavy rope may be rotten at the core;

2. --A thin nylon rope may cut your hands if used improperly;

3. --Manila is the standard for fine rope, but if it is mistreated, it
is subject to rot;

4. --Sisal is cheaper, but very coarse;

5. --Nylon is a rope that stretches under tension, and may react like a
rubber band;

6. --Dacron will not stretch; is that better or worse than nylon?

7. --Binder Twine is designed for and should only be used for binding or
marking. Putting a strain on such is dangerous.

C. Rope Materials, Types, Breaking Strengths, Weakening Points and
Maintenance:

1. Materials:

a. --Rope is made of Manila, Sisal, or synthetic fibers (Nylon and
Dacron).

b. --Other materials may also be used such as cotton and other
vegetable yarns in the making of clothesline, sash cord, mason's line,
and the like. They are widely available but inferior,

c. --Manila is the standard against which all other rope is
measured. If the synthetics overcome Manila's breaking point and
rotting, there are also shortcomings and peculiarities (stretching,
hardening, special splicing procedures, etc.).

2. Types:

a. --Laid Rope; Natural and Synthetic Fibers are often twisted into
yarns, the yarns into strands, and then the strands twisted into ropes
in such a way that the twists are equalized so that the rope is stable
but flexible. This is called "laying." This construction permits using
the shorter lengths of natural fibers to make uniformly strong rope, but
it works well with synthetics as well. Such rope come from twine size
up to ship's hawser size. Sizes are given in diameters or
circumferences according to the custom in certain usages.

b. --Woven Rope; Synthetic fibers are often woven or braided into
line or rope in smaller diameters.

c. --Sash cord or Clothesline; is woven of cotton and glazed with
starch or other filler. It is unreliable for marine usage.

d. --Binder Twine; This material is usually made of inferior
materials, and is unreliable and dangerous for marine usage. Use of
this twine should be avoided, except for the wrapping of small packages.

3. Maintenance:

A good rope is a major investment worth good maintenance practices:

a. --Keep it clean and dry, free of mud and grease;

b. --Replace worn spots by splicing;

c. --Uncoil and coil rope properly, and maintain it free of kinks;

d. --Prevent it's untwisting or "frazzling" with a whipping;

e. --"Red Tag" all rope unsafe for normal use or loading.

4. Breaking Strengths:

The strength of rope in a any given situation can be complicated, so
some consideration must be given to it to avoid injury to yourself or to
others:

a. --Approximate Breaking Strength (Lbs Dead WT.)

Dia.     Sisal       Manila       Poly*    Dacron     Nylon
(In.)

1/4"      480          600        1050       1600       1800

3/8"    1080        1350        2200       3300       4000

1/2"    2120        2650        3800       5500       7100

3/4"    4320        5400        8100     11000     14200

1"       7200        9000      14000     18500     24600


*Polypropylene

Remember the following items with the above data:

b. --Safe Working Load-- one-fourth of the breaking strength (new
rope-with average rope of medium usage it is best to consider 1/6 of
breaking strength as safe working load);

c. --Jerking or dropping the load doubles the strain on the rope in
use;

d. --Any knots / splices used to lengthen the rope reduces the
ropes strength; the following examples apply;

e. --Knots put the rope in shear---that's how knots work---and
that shear tends to beak or weaken rope fibers;

(1) --"overhand knot" reduces a rope to 45% of normal;

(2) --"bowline or square knot" reduces a rope to 50% of
normal;

(3) --"sheet bend or bowline on a bight" reduces a rope to 60%
of normal;

(4) --"splicing" cuts the rope's strength by only 5 to 10%.

(5) --So, using the above data rather than use 1/4 ' manila
to lower a 125 lb. boy over a cliff edge, it might be a better idea to
use 3/8" rope of the same material, even if the rope was new.

To complete this lesson, and experience the quiz feature, click here to take the quiz.

References:

--"Field book", Boy Scouts of America, 1973;

--Percy W. Blandford, "Practical Knots and Rope work", Tab Books Inc.,
Blue Ridge Summit, PA, 1980;

--Clifford W. Ashley, "The Ashley Book of Knots", Doubleday, New York,
1944.

Mr. James L. Mathews, a fully qualified Sailing Master,  holds a Bachelor of Arts degree in Social Studies with Honours, a Major in North-American History and Minors in English and Geography. He also holds a Master of Arts degree in Education and Reading with Distinction. Mr. Mathews is honoured to be included on the roster of the Phi Kappa Phi Honor Society of the University of San Diego. Further, he holds Teaching Credentials in California for K-12 in History and English.

Copyright © 2000, James L. Mathews. All rights reserved, worldwide.
No permission or license is granted for commercial use of this material.