SEAMANSHIP
CH. 9 ANCHORING
The study references for this chapter are again found in
Chapman’s Piloting, Seamanship and Small Boat
Handling, along with this Power Point Presentation and
the USCG Auxiliary Student study guide and practice
questions.
ANCHORING QUESTIONS TO
CONSIDER
1. The process of anchoring is mostly a combination of “a
SEAMAN’S EYE and common sense”.
2. What do you want the anchor to do?
3. How big an anchor do you need?
4. Where will you be anchoring?
5. Where will you keep it on the boat?
6. Who will handle the anchor
WHAT DO YOU WANT THE
ANCHOR TO DO?
1. You want the anchor to HOLD THE BOAT WHERE YOU PUT
IT.
2. That implies that the anchor must STAY where you PUT it.
3. It must be light enough to comfortably handle and yet heavy
enough to dig in and hold the bottom.
4. It must be designed for the bottom types you will encounter the
most.
5. It must hold in all kinds of weather, seas and current.
HOW BIG AN ANCHOR DO YOU
NEED?
1. A mistaken concept is that the effectiveness of anchor depends
upon the weight, for it’s holding power. For most Auxiliary
vessels ( 16-26 ft.) a utility – type 12-18 lb. type is satisfactory.
Deeper draft vessels may need a little more.
2. The anchor’s holding power depends on the design.
3. There are anchors designed for every type of bottom known. Try
to choose the anchor for your vessel’s weight, handling
characteristics, use and area of operation bottom type.
4. They are made from aluminum, steel, cast iron and bronze,
depending on the desired use.
DESIGN
1. The primary motivation for the design of an anchor, is it’s
HOLDING POWER.
2. Most of the characteristics of the anchor reflect it’s ability to
“DIG IN” and continue to hold, without turning over, flipping, or
simply breaking loose.
3. Additional considerations are its ability NOT to foul on anything
it may encounter.
4. Finally, the ease of maintenance feature must be considered.
WHERE WILL YOU BE
ANCHORING
1. Bottom type is probably the greatest item of consideration for the
TYPE of anchor you will need. Consult your navigation chart in
your operating area. It’s printed right on it.
2. Lightweight anchors such as the Danforth-type by Danforth or
Fortress, the Plow, the Delta, the Bruce, the Max, the Kedge, the
Navy-type and the Grapnels, Folding – types, and the Northill
and Mushroom – type are either general – purpose or designed
for a limited range of specific uses.
3. Bottom - types such as hard, rocky, gravel, sand, mud, grass or
coral are often found in combination and must be taken into
consideration for true successful anchoring.
STORING THE ANCHOR
1. It and all other accompanying gear such as the rode, should be
stored in a location “FOR IMMEDIATE USE” mode.
2. It should remain free of all entanglements or any fouling
apparatus.
3. There should be ample room for the rode to run free.
WHO WILL HANDLE THE
ANCHOR?
1. Do not buy an anchor that cannot be comfortably
handled by your crew. It will not be a satisfying
experience.
2. Consideration should be given to the physical
capabilities of the crew including their eyesight, hearing
capabilities, their limitations, training and knowledge of
the functions and importance of ANCHORING.
ANCHOR TYPES
MORE ANCHOR TYPES
& NOMENCLATURE
Flukes
Shank
Bill or Pea
Arm or Tripping Palm
Crown
Ring or Jew’s Harp
YACHTSMAN’S ANCHOR
1. Almost a generic name for a number of different styles, all
lightweight and designed for average holding power. Easy to
handle and reliable.
2. The stock enables the anchor to remain orientated so as to
maintain its maximum holding power, as long as this is not
“broken” by the incorrect tension on the rode raising the shank
to too high an angle.
3. Somewhat antiquated in design now but still an efficient anchor.
SAMPLE ANCHOR TYPES
**** Most anchors do rather poorly in GRASS.****
1. FORTRESS anchors can be assembled in two ways to enable
them to increase their efficiency. They have great holding
power and are of lightweight aluminum.
2. The DANFORTH itself is the popular choice. Made from
aluminum or steel. Great holding power. Excellent balance.
3. The PLOW ( or CQR): Excellent on wide range of bottom
conditions.
4. The BRUCE anchor: Developed for offshore oil rigs it has
been scaled down for small boats.
SPECIALIZED TYPES
1. The KEDGE
2. NAVY – TYPE
3. GRAPNELS
4. FOLDING TYPES
5. THE NORTHILL
6. MUSHROOM TYPE
THE KEDGE, NAVY AND
GRAPNELS
KEDGE – types: The Hereshoff, Fisherman and the Yachtsman. All
Excellent on heavy grass or weed bottoms. Also commonly used to
“kedge” a grounded boat off the bar.
NAVY – types: Not the best for small boats. They must weigh far too
much before their holding power becomes efficient. Used on big
ships because they are flukeless so as to be retrieved into hawse
pipes.
GRAPNELS: Not recommended for small boats. Good in rocks.
Must use a tripping line to free them otherwise, you are permanently
attached to the bottom!
ADDITIONAL TYPES
1. FOLDING TYPES: Some sacrifice to holding power
and strength. Good on rocks and also on grass and
weeds when properly rigged. Not too good in soft sand
or mud.
2. The NORTHILL: Excellent for stowage. Made from
stainless steel. Again, it is a foldable similar to the
grapnel in appearance.
3. MUSHROOM – type: The smaller weights are very
popular for very small boats, dinghy's, canoes, etc. . The
larger sizes are popular for permanent moorings,
holding huge vessels in the thousands of tons.
TWISTED THREE STRAND
NYLON
1. All of the gear, collectively, between the anchor and the boat, is
called the “ANCHOR RODE”, whether it is of chain, synthetic
fiber or a combination of both.
2. The most widely used material for the anchor line is threestrand twisted or double braided nylon. Chain makes a good
rode but the weight is generally prohibitive.
3. DOUBLE-BRAIDED NYLON is elastic. The stretch qualities
(15%-25%) make it ideal for stress loads in heavy seas while at
anchor. Stow it out of the direct sunlight!
BRAIDED SYNTHETIC LINE
1. DOUBLE BRAIDED NYLON: Gives exceptional stability
without the twisting characteristic of the twisted variety. No
kinks. Can be easily faired through fittings and into storage. You
need to “fake” it down to prevent a “set”.
2. It is less subject to chafing, but is slightly less elastic ( only about
14 %, compared to twisted nylon ).
CHAIN
1. CHAIN is for vessels which would require too large a diameter of
nylon for an efficient anchor line. It can be used, however, as a
personal choice.
2. In heavy coral or rock areas, chain is ideal and in some cases,
indispensable to reduce or eliminate excessively heavy chafing.
3. BBB, PROOF COIL and HIGH TEST CHAIN( the best ): The
three kinds of chain most commonly used as anchor chain.
4. CHAIN must be matched to the “wildcat” used to hoist and
lower it.
5.
IDEAL COMBINATION: Nylon ,with 6-8 ft. or longer length of
chain. Chain helps to keep angle of stock very low to bottom for
max dig power of flukes.
ANCHORLINE HARDWARE
EYESPLICE – THIMBLE - SHACKLE
PREFERRED METHOD to bend the anchor line to the anchor is to
thread a shackle through the eye of the shaft; and secure the
shackle bolt through the end link of chain.
On the other end of the chain, another shackle but this time,
secure the shackle pin through a THIMBLE , which has been
worked into an EYESPLICE in the end of the anchor line, to
prevent chafing. Safety wire the shackle pins to prevent them
from turning out.
OTHER FASTENINGS: The bowline or the anchor bend or any
other acceptable knot may be used but care should be taken to
use one which can be broken down easily.
CLEATS, SAMPSON POSTS,
BITTS, CHOCKS, ETC.
ALL FITTINGS: Should be through-bolted and backed up with steel
plates, to reduce the possibility of a strain on the anchor line which
has been secured to this hardware, pulling the bolts back through
the deck or anchoring surface.
REMEMBER: It is the objective of the anchoring maneuver, to keep
the boat’s position stationary. If the fittings pull out and the anchor
runs free or drags as a result, the failure of the fitting may
jeopardize the vessel’s safety.
SCOPE
DEFINITION: The length of the anchor rode in relation to the
height of the bow above the bottom of the water body ( R÷ Bh )
where R = Rode length and Bh = Bow Height of the bow above
the water.
Interpretation and application: The length of the rode.
1. You know you should have a minimum scope of 5 : 1 but should
have 7 : 1 in fair weather. You have 80 ft. of rode out in 10 ft. of
water which gives you a scope of 8:1 (80 ÷ 10).
2. However, if your bow is 3 ft. above the water your actual scope is
only (80 ÷ 13 = approximately a little more than 6!
3. *** The SCOPE is a MAJOR FACTOR that determines whether
you will DRAG or HOLD!!***
ANCHORING – FAVORABLE
CONDITIONS
MARKING A LINE FOR SCOPE
1. One of the marks of a professional seaman are the little plastic
tabs with depth numbers on them, which have been inserted
between the strands of anchor and towing lines, especially but
also for any other line where LENGTH is a key factor.
2. Plastic CABLE MARKERS are inexpensive, permanent, easy to
apply and take the guesswork out of length requirements
altogether.
3. They also display a distinctive character attribute of the owner; a
desire to “do it right”.
PERMANENT MOORING
SELECTING THE ANCHORAGE
1. ALWAYS USE YOUR CHART to pick your anchorage. It’s your
“road map” to the area, in detail.
2. Try to pick a bottom that has little or no mud, loose sand or
heavy grass, for better holding characteristics for the anchor.
3. Try to anchor with your bow into wind. This will help to keep
your sleeping area free of insects living on the surrounding land
mass. It also will help in getting underway as you are already
heading out and you do not have to turn around!
4. Try to pick an orientation which will give you as much lee as
possible, in case of inclement weather.
APPROACHING THE
ANCHORAGE
1. Keep in mind, if you use only one anchor, you are free to rotate
360 degrees on your anchor during the night or day, possibly
over dangerous rocks below or into other anchored boats in the
anchorage. Keep this in mind in choosing the spot and when
approaching.
2. Use your GPS or suitable range marks you have chosen, to
navigate to the desired spot to drop the anchor.
3. Visualize other vessels already anchored and how they might
swing or set up in any current or wind, before your final selection
of a good spot.
LETTING GO THE ANCHOR
THINGS TO CONSIDER
1. BOAT’S MOTION
2. LOWERING THE ANCHOR
3. SETTING THE ANCHOR
4. DRAGGING ANCHOR
5. DECK FASTENERS
LETTING GO THE ANCHOR
1. As a good sailor, your anchor and all the necessary gear is
“ready”.That means it is properly and adequately attached with
secure fittings, backed, and the deck is cleared for working.
2. STOP ALL HEADWAY. Reverse you engine at idle speed. Just as
you begin noticeable sternway, lower the anchor slowly but
positively until it hits the bottom on the crown.
3. The goal is to PREVENT fouling.
SETTING THE ANCHOR
1.
An anchor MUST be SET to yield it’s FULL HOLDING POWER.
2.
This is somewhat “trial and error” because every boat is different.
3.
Pay out the rode until you get to your pre-selected marker. Take a turn or two
around a cleat. Check things out to see if it is holding.
4.
Keep doing this until you are satisfied it is holding.
5.
When you are satisfied, stop the rode with whatever system you have.
6.
Pick out at least two ranges, one on each side at about 45 degree angles to each
other and make a note. Your “anchor watch” can detect drift by these
sightings later and take corrective action..
WHEN THE ANCHOR DRAGS
1. Check the bearings of the two ranges you chose when you came
into the anchorage.
2. Be prepared to get underway immediately and to fend off, if
necessary.
3. If there is no immediate danger of collision and you have
enough room, let out additional scope and test for holding each
time.
4. On the engine, bring the bow back into the wind to ease the
strain on the rode.
5. If it is reasonable, raise the anchor to clear any fouling that
might have taken place.
INCREASING THE HOLDING
POWER
1.
SENTINEL: A weighted device you can slide down the rode, with an attached
“tether line” to control how far down on the rode you want it.
2.
This device sets a “sag” in the rode which reduces the angle between the rode
and the bottom, making the anchor flukes dig in better; making it more
difficult to pull out thus increasing it’s holding power.
3.
A length of heavy anchor chain will work good also to achieve the same result.
4.
An anchor buoy set midway between the bow and the anchor will also help to
relieve the strain on the anchor in heavy seas, and reduce the threat of pulling
the anchor out.
5.
You can combine the buoy, chain and sentinel if necessary.
CLEARING A FOULED ANCHOR
1. Best method is to rig the anchor with a BUOYED TRIP LINE,
secured to a ring on the crown and attached to a cleat on the
boat, BEFORE YOU LOWER IT. Retrieving this line will
break the anchor lose and you can pull it in backwards, further
helping to wash grass or mud from it, or breaking it out from
rocks.
2. Try running a heavy length of chain down the rode, with a line
attached to it. From another boat or dinghy, from 180 degrees
to your rode, pull your anchor loose.
3. If the anchor is deep in heavy clay, wait until low water;
shorten up on the rose as tight as you can get it and wait for
rising water to do the job.
GETTING UNDERWAY
1. ALWAYS have your mainsail up and set or your engine on and in
gear, for positive control, before breaking the loose from the
bottom.
2. Setting in a current, near shore, grass and other like debris will
entangle in the anchor rode.
3. Whipping the line up and down in a snapping motion will help
clear most all of it.
4. Do not store the anchor line with any of this debris as it will
hasten it’s breakdown and carries this moisture down below
decks where it is most undesirable.
5. KEEP THE ANCHOR OFF OF THE HULL!
USING TWO ANCHORS
1. Use of two anchors, a “working” anchor and a “storm” anchor,
will help to correct for deficiencies with only one anchor, when in
heavy weather. The STORM anchor can be run out and set
without moving the working anchor at all.
2. A careful watch must be kept on the lines to see that they do not
become fouled and pull each other loose from the bottom. Cleat
each rode separately to different sides of the boat.
3. Deep draft sailboats will lie head into the wind naturally. Power
boats and small skiffs tend to put their sterns into the wind, if left
alone. It may become necessary to use two anchors with these
vessels to keep them out of trouble.
USING TWO ANCHORS CONT’d
5. Allow for clearing the swing with other obstructions.
4. When anchoring in a tidal or current way, where you know
either will change 180 degrees during the anchorage, set two
anchors at 180 degrees to each other, with the bow at the
midpoint of the two rodes.
6. Two anchors are a must if you wish to orientate your boat in a
fixed position.
7. Never dock on the weather side. Considerable damage is
possible.
8. Stand off and set two anchors on the outside, to hold you off
the weather side of the pier, if practical.
RAFTING TO ONE ANCHOR
1. Do not raft to a single anchor in other then very light current or
calm wind conditions. Otherwise, one or more of the other boats
will cause the single anchor to break loose and ALL will drift.
2. Instead of rafting to the other boat’s anchor, raft to other boat
with your regular docking lines. They are easier and quicker to
break away with.
3. For SAILBOATS, make certain all rigging, especially aloft, stays
clear when rafting.
4. DO NOT leave boats rafted for the night. Each boat should seek
their own anchorage for the night.
ANCHORING AT NIGHT
1. To check for drift at night, you can set your leadline with a little
slack. If it becomes taut, you have drifted and your anchor is
dragging.
2. Don’t forget to pick it up when leaving in the morning!
3. Don’t forget your “ANCHOR LIGHT” to meet your boat’s
requirements of the Rules.
4. In addition, during the day, if you are required to meet the rule,
your SINGLE BLACK BALL dayshape should be flying from
your crow’s nest.
ULTRAVIOLET
1. At the cost of lines today, you will not need too many reminders
of this, but; DO NOT LEAVE YOUR LINES, ANY OF THEM,
EXPOSED TO THE SUN’S ULTRAVIOLET RADIATION ANY
LONGER THAN ABSOLUTELY NECESSARY.
2. If the line must be left on deck, shade it.
3. Dry them, if practical, and store them in a cool, dry place,
preferably your rope locker.
4. Remember: FLEMISH it. FAKE it or COIL it. DO NOT
CHORD IT ( gather it into a lump and throw it in a box!)!
REVIEW QUESTIONS NO. 1
1. The most widely used material for the anchor
line is_________
a. polypropylene
b. polystyrene
c. nylon
d. rayon
REVIEW QUESTIONS NO. 2
2. All gear, taken collectively, that lies between the
boat and it’s anchor is called the _________.
a. line
b. mooring
c. rode
d. cast
REVIEW QUESTIONS N O. 3
3. The lightweight type anchor is excellent on
______ and sand bottoms.
a. rock
b.hard
c. gravel
d. mud
REVIEW QUESTIONS NO. 4
4. Chain is designated by the __________ of the
material in the links.
a. length
b. weight
c. metal
d. diameter
REVIEW QUESTIONS NO. 5
5. The ideal rode for most average conditions is a
combination of _________ and a short length, less than 1
fathom of chain.
a. cable
b. nylon
c. rayon
d. polypropylene
REVIEW QUESTIONS NO. 6
6. When anchoring under favorable weather and sea
conditions and using nylon line, a scope of ________ might
be considered a minimum.
a. 5 : 3
b. 4 : 8
c. 5 : 1
d. 5 : 1
REVIEW QUESTIONS NO. 7
7. When anchoring, the anchor should _____ be
lowered when the boat has any way on.
a. always
b. never
c. probably
d. must
REVIEW QUESTIONS NO. 8
8. If an anchor drags, the first step in trying to get
it to hold is to_______.
a. pay out more scope
b. take in scope
c. change anchor size
d. try another spot
REVIEW QUESTIONS NO. 9
9. When chocks, cleats and other fittings are used
on deck, they must be _________ and reinforced
with a strong backing plate.
a. heavily screwed
b. through-bolted
c. screwed
d. stopped
REVIEW QUESTIONS NO. 10
10. The type of anchor traditionally used for
permanent moorings is the _______.
a. pan
b. mushroom
c. folding
d. navy
END CHAPTER 9