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.
How many types of deck fittings are their?
Bitts, cleats and chocks
Keel? tow types of keels?
- Backbone of the boat.
2. bar keel, flat keel
Keel parts?
frames-Frames are attached to the keel, which extend athwartships (from side to side).
stems- The stem is an extension of the forward end of the keel.
sternpost- sternpost is a vertical extension of the aft end of the keel.
three types of rudders?
- Balanced: blade about half forward and half aft of the rudder post,
- Semi-balanced: more than half of the blade aft of the rudder post,
- Unbalanced: blade entirely aft of the rudder post.
what is pitch?
Pitch is the distance a propeller advances in one revolution with no slip
2 types of frames?
longitudinal- fore and aft
transverse- side to side
Grapnel hook with line is how long?
100’
What is stability?
Stability is defined as the ability of a vessel to return to an upright position after being heeled over.
Center of
Gravity?
The center of gravity is the point at which the weight of the boat acts vertically downwards.
Buoyancy
The buoyancy is the upward force of water displaced by the hull?
Center of
Buoyancy
The center of buoyancy is the center of gravity of displaced water.
Equilibrium
When a boat is at rest, the center of buoyancy acting upwards/vertically is
below the center of gravity acting downwards. It is at this point that a boat is
considered to be in equilibrium.
Rolling
When a boat rolls, the force of the center of gravity will move in the same direction as the roll.
Heel and List
Heel- is temporary lean
List- is permanent lean
Righting moment
A righting moment is the force causing a vessel to react against a roll and return to an even keel.
Static force
Static forces are caused by placement of weight within the hull.
Dynamic force
Dynamic forces are caused by actions outside the hull such as wind and waves.
Free surface effect
Compartments in a vessel may contain liquids as a matter of design or as a result of damage. If a compartment is only partly filled, the liquid can flow
from side to side as the vessel rolls or pitches.
Free communications with the sea
Damage to the hull of a vessel can create free communication with the sea, which is the unobstructed movement of seawater into and out of the vessel.
effects of downflooding
Downflooding is the entry of water into the hull, resulting in progressive flooding and loss of stability.
A lightning “bolt” usually strikes the highest object on the boat, generally the mast or radio antenna.
Full grounding harness is used for protection
How can you tell the distance from thunderstorm?
it takes about five seconds for the sound of thunder to travel each mile.
What are the four types of waves?
refraction
reflection
interference
shoaling water
Types of breakers
Plunging
spilling
surging
line #1 and #4
are used to keep the vessel secured to the dock
2 and #3
from surging fwd and aft
2 springs the stern out
3 springs the bow out
Line #5
foul weather, breast lines (#5) may be used to provide additional holding strength.
pivot point of a boat is approximately
one-third of the way aft of the bow when the boat is underway at standard speed.
When mooring with an off-dock wind, the approach should be made at a
sharp angle - 45° or more.
The coxswain should put the bow at?
a shallow angle (20° to 30°) to the prevailing force and use propulsion and helm to keep from getting set backward,
Pivot point?
The higher the forward speed, the farther the
pivot point moves forward.
what is the breaking strength of Square knot?
46%
what is the BS of a round turn and timber hitch?
30-35% for both
What is a Flare?
Flare is the outward turn of the hull as the sides of the hull come up from the waterline.
Tumble Home?
Tumble home is the reverse of flare and is the shape of the hull as it moves out going from the gunwale to the
waterline
Camber?
A deck usually curves athwartships, making it higher at the centerline than at the gunwales so the water flows off the deck.
Sheer?
Sheer is the curvature of the main deck from the stem to the stern.
The turn of the boat’s hull below the waterline is called the ?
Chine
A propeller consists of blades and a hub. The area of the blade down at the hub is called xx and its outer edge is called the xx
the root
tip
For quick-acting watertight doors, the wheels or handles are turned in the
correct direction xxx
(counterclockwise).
An advisory in coastal waters for winds from approximately 18 to 33
KT inclusive
small craft advisory
A warning of sustained winds in the range 34 to 47 KT, two red pennants
or white over red
gale force
The most troublesome type of fog to mariners is advection fog.
Advection means horizontal movement. This type of fog occurs when warm, moist air
moves over colder land or water surfaces
A knockdown is
when a boat has rolled in one direction xx or greater but does not completely roll over (360º)
90º
A rollover occurs when a boat rolls in one direction and rights itself by completing a xxx revolution.
360º
Tide is the vertical rise and fall of the ocean water level caused by the gravitational attraction of the xxxx
sun and moon.
Side force?
Propeller rotates stbd the stern moves stbd and vice versa with port.