BC Seamanship HB Flashcards
Line used on vessels is classified in two different ways:
- Material used,
2. Size
Lines are categorized as natural fiber or synthetic fiber
4 types of natural-Natural fiber line is made from organic material, specifically, plant fiber = Manilla-abaca strongest, sisal-agave plant 80% of manila strenth, cotton
synthetic-Synthetic fiber line is made of inorganic (man-made) materials. =
Nylon-uv light=good- wet strength=85-90% excellent
polyester-uv light=excellent-“” =verygood 100%
polypro- fair- “” -25 % lighter than nylon verygood 100%
polyethylen- fair- “” 105% fair
How is size measured?
by its circumference or distance around the line.
1 Small stuff – Up to 1.5” in circumference,
2 Line – 1.5” to 5” in circumference
3 Hawser – Everything over 5” in circumference
Lines are measured by ?
Wire is measured by calipers and?
Line = circumferance Wire= diameter
Right lay =
Left lay =
right =Z
Left=S
following describes line types:
Plain-laid-Made of three strands,
Cable-laid-
Plaited- Made of eight strands, four right-twisted and four left
twisted.
braided-Usually made from three strands (sometimes four)
braided together.
double-braided-Made of two hollow-braided ropes, one inside the other.
This line is manufactured only from synthetics, and about 50% of the strength is in the core.
natural fiber line does not recover after
being stretched (elasticity).
when polypropylene is exposed to continuous sunlight.
It can, in fact, lose
up to 40% of its strength over three months of exposure.
Cellulose, the main component in natural fibers will deteriorate with age,
getting more brittle and turning yellow or brownish. When bent over bitts or cleats, the
fibers easily rupture and break.
Damage to internal natural fibers occurs when a line under a strain
exceeds 75% of its breaking strength.
A cockle (or hockle) is actually a kink in an inner yarn that forces the yarns to the surface. A cockle can reduce line strength?
by as much as a third.
If the circumference is reduced by? Also during bending the line strength may decrease up to ?
five percent or more, the line should be replaced.
5 times its strength
Rust stains, extending into the cross-section of natural fiber and nylon fiber yarns can lower line strength
as much as 40%.
It is recommended that three-strand synthetic lines be
faked down on deck and allowed to relax for
twenty-four hours.
Lengths less than 50 feet will relax in one hour when laid out straight.
Nylon is not subject to mildew, and it may and should be scrubbed if it becomes slippery because of oil or grease. Spots may be removed by cleaning with?
a 10% solution of mild detergent/degreaser and
water,
Three-strand synthetic line is often coiled?
clockwise to reduce a natural tendency to tighten up. It can be coiled in figure eights to avoid kinks when paying out.
weakest point in a line is the ?
The eye of the line should be ? times the diameter of the line?
- knot or splice
2. six times
a Knot can reduce the breaking strength of a line by? A splice can reduce up to ?
as much as 50 to 60 percent.
splice, however, is stronger than a knot and can reduce strength by as much as 10-20%
bowline is a versatile knot and can be used anytime a temporary eye is needed in the end of a line.
What is the breaking strength of a bowline?
Two bowlines?
- It also works for tying two lines securely
together, though there are better knots for this. - 37%
- 43% 2 bowlines
half hitches?
Hitches are used for temporarily securing a line to objects such as a ring or
eye.
Rolling hitch?
A rolling hitch is used to attach one line to another, where the second line is
under a strain and cannot be bent
Clove hitch?
A clove hitch is preferred for securing a heaving line to a towline.
Slip Clove hitch?
slip clove hitch should be used in lieu of a clove hitch when a quick release is required.
Single becket bend? what is the BS lost?
- Single becket bends are used to join line of the same size or nearly the same size.
- BS lost is 41%
Double becket bend? what is the BS lost?
- works for joining lines of unequal size.
- BS lost is 41%
crown knot may be used to
prevent an unwhipped line from unlaying.
Splicing natual fiber line and synthetic how many tucks?
A back splice is commonly used to finish off the end of a line and?
Natural= 3
synthetic=4
It can be used on the ends of fender lines.
what is seizing a line? what is round seizing?
- is when an eye must be made in a bight of a line where the line cannot be spliced. Marlin line is the most common used line for this method.
Round seizing is the most common used and most practical method of seizing.
Temporary whipping and permanent whipping? Tools are sail twine, palm & needle
Cut a piece of sail twine or small stuff, in length about ten times the circumference of the line being seized.
Permanent = whipping line to allow for 15 to 20 wraps
Markings for splicing line:
R = Length of fid, or 2 wire fids, from the bitter end
X = Desired loop size (where core will come out)
Mark 1 = Where core comes out of X
Mark 2 = Distance of the short section of the fid from mark 1.
Mark 3 = Length of fid plus one short length of fid from Mark 2.
T = 8 strands towards the bitter end from R.
Z = One-half fid from X towards slip knot.
Slip Knot = 5 fid lengths towards standing line.
