Friday, February 29, 2008


Time of rising and setting of the moon is important, if there is a need to work at night it would be nice to know if there will be moonlight, when it will be light and how long. Times of moonrise and moonset are listed in the Nautical Almanac. These times can be computed from the Nautical Almanac for any point on the earth. The listed times in the Almanac, however, are LMT of moonrise and moonset at the Greenwich meridian.

Finding Time of Moonrise and Moonset
Finding the time of moonrise and moonset is similar to finding the time of sunrise and sunset with one important difference. Since these moon phenomena occur later from one day to the next and at variable rates of change, which are rather large (on the average about 51 minutes a day), there could be a considerable error from using time corrected only for latitude and zone time. The arguments for determining the time of moonrise and moonset are the observer's longitude and the differences in times on the two Greenwich dates (tabulated latitudes) that straddle the local date. For ordinary purposes of navigation, however, you would be sufficiently accurate to interpolate between consecutive moonrise or moonset at the Greenwich meridian. Since apparent motion of the moon is westward, relative to an observer on the earth.

Interpolation in west longitude is between the phenomenon on the given date and the following one:
In east longitude it is between the phenomenon on the given date and the
preceding one.

For the givin date, enter the daily-page table for latitude, and extract the LMT for the tabulated latitude next smaller than the observer's latitude, (unless this is an exact tabulated value). Apply a correction from Table I of the Nautical Almanac "Tables for Interpolating Sunrise, Moonrise, etc." to interpolate for latitude, determining the sign of correction by inspection. Repeat this procedure for the date following the given date, if in west longitude, or for the day preceding, if east longitude. Using the daily difference between the times for the nearest tabular latitude, and the longitude, enter Table II ofthe Almanac "Tables for Interpolating Sunrise, Sunset, etc." and take out the correction. Apply this correction to the LMT of moonrise or moonset at the Greenwich meridian on the given date to find the LMT at the position of the observer. The sign to be given the correction is such as to make the corrected time fall between the times for the two dates between which interpolation is being made. This is nearly always positive (+) in west longitude and negative (-) in east longitude. Convert the corrected LMT to ZT.

Thursday, February 28, 2008




When towing more than one barge astern, it is referred to as tandem towing. In a pure sense, tandem means one behind the other. Within the tandem rig are three other methods called the Honolulu rig, Christmas tree rig, and Modified Christmas Tree rig.

In this method, the tug is connected to the first tow. The first tow connects to the second, and so on if additional units are towed
. The intermediate hawser, connecting the first tow to the second, must be streamed and allowed a proper catenary depth. The surging action must be eliminated between tug and first tow and between first tow and second tow.
In this method, the first tow is connected to the main tow wire. The second tow is connected, with an auxiliary tow wire, to the bitts on deck.
The Honolulu rig allows independent connection of the two tows. Disconnecting and control are readily workable.

In this method, all of the barges tow from a single towing hawser
. This is done by means of pendants shackled to flounders (sometimes called bale or fishplates) inserted in the towing hawser.

In the modified Christmas Tree rig, all of the tows are towed from a common flounder, but the last barge will tow as a separate unit

Note: Christmas Tree rigs are preferred for multiple tows. They are stronger and any one unit can be taken from the tow at anytime without disrupting the whole tow. The assistance of another tug is usually required to break up the Christmas Tree rig before entering port.

Tuesday, February 26, 2008


Determine the course to steer at a given speed to make good a desired course with this information: ship’s speed 12 knots, the desired course 095° , the current’s set 170° , and the drift 2.5 knots.

Solution: From point A draw course line AB extending in the direction of 095° (indefinite length).
From point A draw in the current line AC for the set 170° and drift 2.5 knots. Using C as a center, take the dividers, swing an arc of radius (ship’s speed 12 knots) CD, intersecting the line AB at D. Measure the direction of line CD (083.5° ). This is the course to steer. Measure the length of the line AD, 12.4 knots is the speed made good.


Determine what course and speed you must use in order to make a desired course and a desired speed good with this information: desired course 265° , desired speed to be made good 15 knots, current set of 185° , and a drift of 3 knots.

Solution: From A draw line AB in the direction to be made good (265° ) and for a length equal to the speed to be made good (15 knots).

From A draw AC, the set and drift of the current, 185° and 3 knots.

Draw a line from C to B. The direction of this line is 276° ; this is the course to be steered. The length of the line equals the speed required (14.8 knots).

These current vectors can be made to any convenient scale and at any convenient place such as the center of the compass rose, unused area of the plotting sheet, a separate sheet of paper, or directly on the plot.

These current vectors can be made to any convenient scale and at any convenient place such as the center of the compass rose, unused area of the plotting sheet, a separate sheet of paper, or directly on the plot.

Leeway is the leeward motion of a vessel due to wind. It may be expressed as distance, speed, or angular difference between the course steered and the course made good through the water. The amount of leeway depends upon the speed and relative direction of the wind, type of vessel, exposed freeboard, trim, state of the sea, and depth of water. Leeway is most conveniently applied by adding its effect to that of the current and other elements introducing geographical error in the dead reckoning.


SOG is the ship’s actual speed with respect to the earth along the COG. In current sailing, SMG (not SOG) is used.

In navigation, "current" is to include all factors that introduce geographical error in dead reckoning. When a fix is obtained, one assumes that the current has set from the DR position at the same time as the fix and the drift equals the distance in miles between these two positions divided by the hours since the last fix. This is true, regardless of the number of changes of course and speed since the last fix.

If set and drift can be estimated, a better position is obtained by applying the correction to the DR position. This is referred to as an estimated position. If a current is setting in the same direction as the course of the ship or its reciprocal, the course made good is the same, only the speed changes. If course and set are in the same direction, the speeds are added. If in opposite directions, the smaller speed is subtracted from the larger.

For ships crossing a current, three current vector diagrams can be made to give the information needed to determine speed and courses to be steered. These diagrams can be made on scrap paper or an area on the plotting sheet.

Find course and speed made good through a current with ship’s speed 10 knots, course 080° , current set 140° , and drift 2 knots.

Solution: From point A draw the line AB. This represents the course and speed (080° at 10 knots) in length.

From B draw in BC, the set and drift of the current, 140° at 2 knots. The direction and length of AC are the estimated course made good (089° ) and speed made good (11.2 knots ).

For this types of problems I like to use a Radar Transfer Plotting Sheet # 5089 or you can use a Maneuvering Board Sheet # 5090.


The following are some terms used when using dead reckoning:

Heading - The horizontal direction in which the ship points or heads at any given second, expressed in angular units clockwise from 000° through 360° . The heading of the ship is also called ship’s head. The heading is always changing as the ship swings or yaws across the course line due to the seas or steering error.

Course - As applied to marine navigation, the direction in which a vessel is to be steered or is being steered, and the direction of travel through the water. The course is measured from 000° clockwise from the reference direction to 360° . Course may be designated as true, magnetic, compass, or as determined by the reference direction.

DR Track Line - In marine navigation, the graphic representation of a ship’s course normally used in the construction of a dead reckoning plot.

Speed - The ordered rate of travel of a ship through the water is normally expressed in knots. In some areas where distances are in statute miles, such as on the Great Lakes, speed units will be "miles per hour." Speed is used in with time to establish a distance run on each of the consecutive segments of a DR plot.

Fix - A position established at a specific time to a high degree of accuracy. It may be determined by any of a number of methods. A running fix is a position of lesser accuracy, based in part on present information and in part on information transferred from a prior time.

DR Position - A position determined by plotting a vector or series of consecutive vectors using only the true course and distance determined by speed through the water, without considering current

Estimated Position - The more probable position of a ship, determined from incomplete data or data of questionable accuracy. In practical use, it is often the DR position modified by the best additional information available.

Dead Reckoning Plot - called DR plot. In marine navigation it is the graphical representation on the nautical chart of the line or series of lines, which are the vectors of the ordered true courses and distance run on these courses at the ordered speeds while proceeding from a fixed point. The DR plot originates at a fix or running fix, it is labeled as to courses, speeds, and times of various dead reckoning positions, usually at hourly intervals or at times of change of course or speed. A DR plot represents courses and speeds that have been used. A similar plot may be made in advance for courses and speeds that are expected to be used.

Estimated Time of Departure - The estimate of the time of departure from a specified location according to a scheduled move to a new location.

Monday, February 25, 2008





Friday, February 22, 2008






Tuesday, February 19, 2008





Sunday, February 17, 2008








When you are weighing anchor, the same gear must be available on the forecastle as for anchoring. In addition, there is a grapnel (a small four-armed anchor) used to retrieve the anchor buoy. A hose is rigged to wash mud from the anchor and the chain. The windlass is energized and tested, and then the wildcat is engaged. The brake is then released and the wildcat is tested. The
brake is set, and all stoppers but one are cast off. When ready, the report “READY TO HEAVE IN” is made to the bridge.

On the command “HEAVE AROUND,” the brake is taken off and the chain is heaved in enough to take the strain off the stopper. The stopper is then cast off and heaving is resumed. Reports are made to the bridge periodically on the direction the chain is tending, the amount of chain remaining out, and the degree of strain on the chain. If the command were “HEAVE AROUND TO SHORT STAY” the chain would be heaved in just short of breaking out the anchor (pulling the anchor loose from the bottom). When the chain is at short stay, it is reported to the bridge. On the command “HEAVE
AROUND AND UP,” start heaving. When the flukes have broken out, and the crown still rests on the bottom, the report “ANCHOR IS UP AND DOWN” is made.

When the anchor is free of the bottom, it is “AWEIGH”. At this time the anchor ball are hauled down and the ship is now underway. When the anchor comes into view and its condition can be noted, the report “ANCHOR IN SIGHT, CLEAR (or FOUL) ANCHOR” is made. The anchor is reported as housed when the shank is in the hawsepipe and the flukes are against the ship's side. The
anchor buoy is recovered as soon as possible, and a report is made to the bridge when the anchor buoy is on board. The anchor again is made ready for letting go and kept that way until the anchor detail is told to secure it after the ship is outside the harbor or channel.

To secure the anchor for sea, set the brake, then pass the stoppers and even them. Take the brake off, then slacken the chain between the wildcat and the stopper. The brake is set and the wildcat is disengaged. To prevent water from entering the chain locker, secure buckler plates over the chain pipes for those ships with open decks.

Stowing Chain
As the chain comes aboard, it passes along the deck, on metal flash plates, around the wildcat, and down into the chain locker. The chain goes into a locker. The bitter end is secured to a pad eye (ring) on the bulkhead of the chain locker. When working small chain, at least two Seaman should guard against any possible pileup in the chain locker. The chain can be kept from piling up by pushing any accumulation over with a length of 2 by 4 lumber.

A stockless type anchor is housed in the hawsepipe and it is secured by passing the stoppers. The anchor must be drawn taut in the hawsepipe by the outboard stopper to prevent the flukes from banging the sides. Stoppers are attached to the chain by straddling a link with the tongue and strong back of the pelican hook. The bail is then closed on the pelican hook. The toggle that keeps the pelican hook closed must then be inserted in the tongue of the pelican hook and the lanyard secured around the bail to prevent the
toggle pin from coming out. The turn buckles must be adjusted so each stopper will take an equal strain.

Friday, February 15, 2008


When anchoring and weighing anchor, The exact procedure may vary for making the anchor ready for letting go, but the following should be done. The windlass is tested, the anchor in the hawse is freed, the anchor is walked out if anchoring is in deep water or if the bottom is rocky, the brake is set and the wildcat is disengaged. All but one stopper is taken off and the anchor buoy line is shackled to the chafing chain or pendant. The chain locker is checked for loose gear that may become wedged in the chain pipes or come flying

out. An order then is given to stand clear of the chain. For obvious reasons. At the command “STAND BY” the brake is released and two Seamen-one with a sledgehammer or maul-take stations at the stopper outboard side of the chain.

When the command “LET GO” is given, one Seaman pulls the pin from the stopper tongue.The Seaman with the maul knocks the bail off the tongue of the pelican hook and steps clear. As soon as the Seaman is clear, the brake is fully released. If for some reason the stopper does not fall clear, the chain can still be controlled by the brake.The Seaman tending the anchor buoy tosses it over the side. On the bridge, the anchor ball is hoisted. The anchor buoy indicates the actual position of the anchor to which it is attached by floating above it. If an anchor buoy floats on the surface, it is said to be “watching.” An anchor buoy may fail to watch because its line is too short or the line is fouled in the chain. Before anchoring, the line attaching the buoy to the anchor should be adjusted to a length that is a couple of fathoms greater than the depth of the water at anchorage. This extra length allows for slight fouling, tide variations, or the sinking of the anchor in mud, which might cause the actual depth to be greater than that shown on the navigational chart being used.

The anchor buoy and line must be laid up along, and outboard of, the lifelines. It should be put overboard, well clear of the ship the instant the anchor is let go. An anchor buoy is a time-saver in locating an anchor lost in weighing or one that is slipped in an emergency. Slipping an anchor happens when unexpected circumstances do not permit time to weigh anchor. As soon as the anchor hits bottom the brake is set so the chain will not pile on it. As the ship gains sternway, the brake is released to lay the chain out evenly on the bottom and to control any running movement of the chain. As each chain marking passes the wildcat, the report “(Number) FATHOM ON DECK’ is made to the bridge.

The direction the chain is tending is indicated by pointing the arm and/or reporting “CHAIN TENDING (number) O'CLOCK.”
If the chain tends around the stem, the situation is reported to the bridge. The chain must be allowed to run freely or the sharp bend around the stem may damage a link. Detachable links are particularly susceptible to damage.

Maritime Warning System ( NAVTEX )

NAVTEX is a maritime radio warning system consisting of a series of coast stations transmitting radio teletype (CCIR Recommendation 476 standard narrow band direct printing, sometimes called Sitor or ARQ/FEC) safety messages on the international stan­dard medium frequency 518 kHz. Coast stations trans­mit during preset time slots so as to minimize interference with one another. Routine messages are normally broadcast four to six times daily. Urgent mes­sages are broadcast upon receipt, provided that an another station is not transmitting. Since the broadcast uses the medium frequency band, a typical station ser­vice radius ranges from 100-500 NM day and night. In­terference from or receipt of stations farther away occasionally occurs at night.

Each NAVTEX message broadcast contains a four-character header describing identification of sta­tion (first character), message content (second charac­ter), and message serial number (third and fourth characters). This header allows the microprocessor in the shipborne receiver to screen messages, selecting only those stations relevant to the user, messages of subject categories needed by the user, and messages not previously received by the user. Selected messages are printed on a roll of paper as received, to be read by the mariner at his convenience. Unwanted messages are suppressed. Suppression of unwanted messages is more and more important to the mariner as the num­ber of messages, including rebroadcasts, increases yearly. With NAVTEX, a mariner will no longer have to listen to, or sift through, a large number of irrelevant data to obtain the information necessary for safe navigation.

Vessels regulated by the Safety of Life at Sea (SOLAS) Convention, as amended in 1988 (cargo vessels over 300 tons and passenger vessels, on interna­tional voyages), and operating in areas where NAVTEX service is available, have been required to carry NAVTEX receivers since 1993. The USCG voice broadcasts (Ch. 22A), of more inshore and harbor information, will remain un­affected by NAVTEX. Mariners not able to man a radio on a 24-hour basis in order to hear critical warning messages, commercial fishermen should also find a advantage in owning a NAVTEX receiver. NAVTEX coverage is reasonably continuous to 200nm off the U.S East, Gulf, and West Coast, Puerto Rico, Southwest Alaska, Hawaii, and 300 - 400 nm off Guam.

Thursday, February 14, 2008


Anchor chains are marked as follows:
The detachable links are painted red, white, or blue,

Red for 15 fathoms

White for 30 fathoms

Blue for 45 fathoms

Red for 60 fathoms

White for 75 fathoms and so on.
At the 15-fathom mark, one link on each side of the detachable link is painted white and one turn of wire is wrapped securely around each stud. At the 30-fathom mark, two links on each side of the detachable link are painted white, and two turns of wire are wrapped around the studs of the second links from the detachable link. At 45 fathoms, three links on each side of the detachable link are painted white, and three turns of wire are wrapped around the studs of the last white links. At 60 fathoms, four, white links are on each side, and four turns of wire are wrapped around the last white studs. (And so on for each shot.)
Each link of the entire next to last shot is painted yellow, the last shot is entirely red. These last two shots give warning of the approach of the bitter end ofthe cable.


Ground tackle is all equipment used in anchoringand mooring with anchors and buoy mooring with chain and appendages. The following are defined as groundtackle: Anchors, Anchor chain, wire rope, synthetic line, or combinations of these materials, when used with anchors. Appendages consisting of connecting shackles or links, detachable links, pear-shaped links, end links, bending shackles, mooring shackles, mooring swivels, detachable-link tool sets, clear hawse pendants, dip ropes, chain stoppers, wrenches for chain stoppers, outboard swivel shots, chain cable jacks, mooring hooks, chain hooks, anchor bars, and anchor buoys.

Ground tackle is one of the most vital parts of a ship's equipment. The vessel's safety frequently depends upon the proper use of this gear. The anchor windlass, equipped with capstan head or gypsy heads, is a part of the ship's ability to handle its ground tackle and use the capstan or gypsy heads in mooring and warping operations.


All anchors are designed to take hold as quickly as possible after they hit bottom. They take hold in one of two ways: either by hooking into the ground with one or both of their sharp flukes or by burying themselves completely. When an anchor is let go in fairly deep water, it strikes the bottom crown first


From this position, any drag on the chain causes the flukes, if properly set, to dig into the bottom. As the drag continues, the fluke is forced further into the bottom. If the proper scope of chain is used, the heavier the drag, the deeper the fluke will dig in, developing the full holding power of the anchor.


Chain, wire rope cables, or cable composed of both chain and wire rope for use with ships' anchors is a part of the ship's ground tackle. Ground tackle

is the term applied to all equipment used in anchoring. It includes the anchors, their chain or cables,

connecting fittings, and all associated equipment used in anchoring, mooring with anchors, buoy mooring, being towed, or securing or letting go anchors in or from their hawsepipes.

Wednesday, February 13, 2008


When splicing wire, always insert the marlinespike against the lay of the wire, and make sure not to shove it through the core. The core must be on the left-hand side of the spike.

Making the first tuck of strands one, two, and three. In the liverpool splice, the first strand goes under three strands, the second strand goes in the same opening but only under two strands, and the third strand goes in the same opening but only under one strand. All of the strands go in at the same point, but come out at different places. At this time, run the spike behind the three strands under which the first three are tucked, but above the first three tucked strands. Holding the marlinespike at a 90-degree angle to the standing part, turn the spike counterclockwise about one fourth of a turn and insert the core through the standing part. This is called "dipping the core." Make sure that the core is inserted under the marlinespike. Pull the core down and run it down into the splice.

Tucking strands four, five, and six. Remember that the core was last between strands three and four and that the strands are numbered clockwise. To tuck strand four, put the marlinespike under the strand to the left of where one, two, and three were tucked through the standing part. Turn the marlinespike counterclockwise around the standing part and tuck the strand. Pull it tight and run it down with the spike. Tuck strand four around the same strand four times. Lock each tuck in place by holding the strand down and running the spike up. Push the marlinespike under the next higher strand on the standing part and tuck strand five around it four times, using the same procedure as with strand four. Then tuck strand six four times. This completes strands four, five, and six.

Running the core up. Burying the core in the center of the splice in the standing part is called "running the core up." Part of the core is run up and the excess is cut off. This is done before each of the first strands is tucked three more times. Run the spike under the same three strands under which number one strand was passed. With the spike in your left hand and the core in your right hand, move the spike to the left and down, and pull up the core with your right hand to tighten it. Then move the spike back to the right. Next run up the core into the center of the splice and cut off the excess.

Tucking strands one, two, and three. To finish the splice, tuck number three, two, and one. Each is tucked three times in a row, ending up with an overall total of four tucks for each. To avoid kinking the strands on the last tucks, insert the spike and run it up the wire. Follow the spike up with the strand, shove it under the spike, and pull taut. Keeping a strain on the strand, work the spike and strand back around and down together. Hold the strand there and work the spike back up the wire. Follow up with the strand and take the last tuck. Work the strand back down and hold it there. Before pulling out the spike, run it back up until the strands of the standing wire bind the working strand in place. Make the second and third tucks with the remaining strands in the same way.

Completing a splice. Remove the wire from the vise, use a hammer to pound the splice into shape, and cut off the ends of the tucking strands close to the splice.

Tuesday, February 12, 2008



Monday, February 11, 2008



Sunday, February 10, 2008


Standard Shot
The lengths of chain that are connected to make up the ship's anchor chain are called shots and are made up with an odd number of links. A standard shot is 15 fathoms (90 feet) long. At the time of its manufacture, each shot of the chain usually has a serial number stamped, cut, or cast on the inner side of the end links of each shot. If an end link is lost or removed from a
shot, this identification should be cut or stamped on the inside of the new end link of the altered shot.
Detachable Links
Shots of anchor chain are joined by a detachable link, The detachable link consists of a C-shaped link with two coupling plates that form one side and stud of the link taper pin holds the parts together and is locked in place at the large end by a lead plug. Detachable link parts are not interchangeable, so matching numbers are stamped on the C-link and on each coupling plate to ensure its identification and proper assembly. You will save time and trouble trying to match these parts if you disassemble only one link at a time and clean, slush, and reassemble it before disassembling another.
When you re-assemble a detachable link, make sure the taper pin is seated securely. This is done by driving it in with a punch and a hammer before inserting the lead plug over the large end of the pin. Detachable link toolbox sets contain tools, including spare taper pins and lead plugs, for assembling and disassembling links and detachable end links.


Helicopter evacuation of personnel
Helicopter evacuation, usually performed by the Coast Guard, is a hazardous operation to the patient and to the flight crew, and should only be attempted in event of very serious illness or injury. Provide the doc­tor on shore with all the information you can concern­ing the patient, so that an intelligent evaluation can be made concerning the need for evacuation. Most rescue helicopters can proceed less than 150 miles offshore (a few new helicopters can travel 250 to 300 miles out to sea), dependent on weather conditions and other vari­ables. If an evacuation is necessary, the vessel must be prepared to proceed within range of the helicopter, and should be familiar with the preparations which are necessary prior to and after its arrival. Give the accurate position, time, speed, course, weather conditions, sea conditions, wind direction and velocity, type of vessel, give complete medical information including whether or not the patient is ambulatory. If you are beyond helicoper range give your diversion intentions so that a rendezvous point may be selected.

Preparations prior to arrival of helicopter
Select and clear the most suitable hoist area, preferably aft on the vessel with a minimum of 50 feet 15.2 meters radius of clear deck. This must include the securing of loose gear, awnings. and antenna wires. Trice up running rigging and booms. If hoist is aft, lower the flag staff. If the hoist is to take place at night, light the pickup areas as well as possible. Be sure you do not shine any lights on the helicopter, so that the pilot is not blinded. If there are any obstructions in the vicinity, put a light on them so the pilot will be aware of their positions. Be sure to advise the helicoper of the pickup area on the ship before the helicopter arrives, so that the pilot may make his approach to aft, amidships, or forward, as required. There will be a high noise level under the helicopter, so voice communications on deck are almost impossible. Arrange a set of hand signals among the crew who will assist.

Hoist operations
If possible have the patient moved to a position as close to the hoist area as his condition will permit, time is important. Normally if a litter is required, it will be necessary to move the patient to the special litter which will be lowered by the helicopter. Be prepared to do this as quickly as possible. Be sure the patient is strapped in, face up, and with a life jacket on (if his condition will permit). Be sure that the patient is tagged to indicate what medication, if any, was administered to him and when it was administered. Have the patients medical record and papers in an envelope or package ready for transfer with the patient. If the patients condition permits be sure they are wearing a life jacket. Change the vessel's course to permit the vessel to ride as easily as possible with the wind on the bow, preferably on the port bow. Try to choose a course to keep the stack gases clear of the hoist area. Once established, maintain course and speed. Reduce speed to ease the ships motion, but maintain steerageway. If you do not have radio contact with the helicopter, when you are ready for the hoist, signal the helicopter in with a "come on" with your hand, or at night by flashlight signals. Let the basket or stretcher touch the deck before handling to avoid static shock. Do not secure the cable or trail line to the vessel or attempt to move the stretcher without unhooking.

Saturday, February 9, 2008


Finding your Location

Step 1
You can express your position by Latitude and Longitude

Step 2
Mapmakers or geographers use an imaginary grid to locate a place on a map. This grid is made up of intersecting lines of latitude and longitude.

Step 3
Lines of latitude run east and west around the globe. The latitude is measured in degrees north and south from the Equator.
Lines of longitude that run north and south from North pole to the South pole are measured in degrees east and west from the Prime Meridian.

Step 4
Prime Meridian runs through Greenwich, England. It is the planet’s Home Base.

Step 5
You can find the longitude of your location with an accurate sense of time. Before you can do any longitude calculations, you must convert your local zone time, as shown on your watch, to GMT (Greenwich Mean Time, the clock time back at Greenwich).

Step 6
The local zone time is the local clock time which is the mean solar time of central meridian of your local time zone.
In several places in the world, hundreds of different times were adopted, each one corresponding to its own meridian. To simplify this situation, the Earth surface was divided into 24 time zones, each one delimited by two meridian forming a hour angle of 1 hour at the poles. The mean solar time of the central meridian of each time zone was assigned by convention to all places belonging to the time zone.

Three Basic Ideas to find Longitude

Step 7
Basic Idea1: The first of these ideas is the relationship between time and the rotation of the Earth. It takes an average time of 24 hours for the Earth to rotate 360 degrees. If you divide the number degrees in a circle by the number of hours in a day, we find that the Earth turns 15 degrees each hour.
360° / 24 hours = 15° per hour
We can take this a step further and state that the Earth turns one degree in four minutes.
1 hour = 60 minutes / 15° = 4 minutes per degree.

Step 8
Basic Idea 2: The second idea is that we have to be careful about the difference between the events and time. Events like sunrise in the east always happen before the same event in the west. But time as shown on eastern clocks is later than on western clocks at the same instant. We can summarize this concept:
Local time earlier, position is westward.
Local time later, position is eastward.

Step 9
Basic Idea 3: The third and last idea needed for longitude is the applying of Equation of Time.
Whenever I've mentioned clock time, I've called it average time. Clock time and Sun time are different by as much as 16.5 minutes. The important thing is that if you're going to compare Sun time to the chronometer's clock time, you have to change the chronometer's clock time to Sun time so that you're comparing like terms. And that's what the Equation of Time does. You can find the Equation of Time from the Nautical Almanac.
By applying the Equation of Time to the chronometer's clock time, we convert Greenwich Mean Time (GMT:Clock time.) to Greenwich Apparent Time (GAT:Sun time). GAT is simply the Sun time back at Greenwich, England.

Step 10
Now we can observe Local Apparent Noon and do our simple subtraction of GAT to find our longitude.
It is noon at the very instant that the sun were right over your head.
Local Apparent Noon is simply noon for your exact location, and sets your watch to 12:00 based on Sun Time. The time of Local Apparent Noon, recorded as 12:00 local time, is compared to the time back in Greenwich.

Friday, February 8, 2008




Here are some search patterns that you could use if a vessel or aircraft went down.

In any situation, think about this while doing a search

(1) what are you looking for? ship - Liferaft - man in the water.

With all of the above you must then take the following into consideration.

(a) The weather
(b) The strength of the tide
(c) The wave height
(d) The temperature of the water

with the above information and regarding the following, then think about this

Sea is like a mirror, then the searches can be pretty wide
Storms, large waves and strong tides, then the searches must be very tight

There are various searches that can be carried out, the following searches are recognised in the IMASAR Manual.

Expanded Square Search

Downwind for 1 miles, alter to starboard 90 degrees, go down this course for 1 mile,
Alter 90 degrees to starboard and go down this course for 2 miles
Alter 90 degrees to starboard and go down this course for 2 miles
Keep adding 1 mile ever time you alter to starboard

These distances are just for examples

Sector Search Pattern

Go Downwind for 1 mile,
alter 120 degrees to starboard, this course for 1 mile
Alter to starboard 120 degrees and go on this course for 2 miles going through datum
Alter to starboard 120 degrees for 1 mile
Alter to starboard 120 degrees for 2 miles going through datum
Alter to starboard 120 degrees for 1 mile
Alter 120 degrees to starboard for 1 mile back to datum

then go down the Blue track as follows
Alter 30 degrees to starboard for 1 mile
then go to the above and do the same again
then go down the Black tracks as follows
Alter 30 degrees to starboard for 1 mile
then go down the above and do the same again

These distances are just for examples

Parallel Search Pattern

With this search it can be done with 1 or more vessels
The main vessels starting the search are the two back arrows next to datum (Black square)
They will go up past datum and after a certain distance will turn away from each other at 90 degrees
then at very short distances on this track will turn and go parallel to each other on reciptical courses
they will do this until told to stop

Other vessels (Red arrows) will take the next berth alongside the main 2 search vessels and also turn away from each other

Williamson Turn

For this demonstation, assume your going Due North

Turn towards the side that the man fell overboard, (in this case he's fell over the starboard side)

Alter till you see 060 degrees on your compass

Alter hard to port till you see 200 degrees on your compass

Square up your helm to amidships, this will take you down on a reciptical course

Wednesday, February 6, 2008


For tugs working inside harbors and for towing short distances or in confined areas where constant control is required, towing alongside or the hip tow is the preferred method. A hip tow can be made up on either the port or starboard side of the tug. There are various ways of making up a hip tow, here are some standard things to keep in mind.

Making Up a Hip Tow
Three lines should be used, the spring line, the bowline, and the stern line. For large or heavy tows, you may want to double up on the towlines and also use a bow breast line. Before the tug goes out to make up for a hip tow, the towing lines must be inspected and made ready. Inspect the lines for signs of chafing and the eyes and the eye splices for fraying or breaks. Check the towlines for wear and breaks. If you find a line damaged or one that you have doubts about, point it out to the operator. When selecting the lines to be laid out, the usual procedure is that the best line is used for the spring line. This serves as the towline and takes the greatest strain. The second best line is used for the bowline, and the third best line is used for the stern line. The lines are then faked down (they are laid out so that they are free of kinks and obstructions). They can then be paid out rapidly when they are needed.
The tug secures to one side of the tow with her own stern abaft of the stern of the tow. This will increase the effect of the tug’s screw and rudder. The side chosen depends on how much the tug must maneuver with the tow.

If all turns are to be made with the tug’s screw going ahead, she will be more favorably placed on the outboard side of the tow, the side away from the direction toward which the most turns are to be made.

If a sharp and difficult turn is to be made under headway, the tug should be on the side toward which the turn is to be made. Here she is placed for backing to assist the turn, because as she slows, the tow’s bow will turn toward the side the tug is on.

If a turn is to be made under no headway, the tug is more efficient on the starboard side of the tow. When the tug backs to turn, the port send (side force) of her screw will combine with the drag of the tow to produce a turning effect greater than that which could be obtained with the tug on the port side.

The best position for a long back in a straight line is to have the tug on the port side. Then the drag of the tow tends to offset the port send of the backing screw.
The towing line or spring line, usually a 6-inch (or larger) hawser, is led from the forward towing bitts on the tow side of the tug to the aft set of bitts on the tow. This line is secured first. Then the tug eases ahead with her bow turned in to take out all of the slack.

Next the bowline or backing line is paid out over the outboard side of the bow stem or king post and lead to a bitt on the forward end of the tow. Once the bowline is secured on the tow, all the slack is taken in and the bowline secured. This will bring the tug into proper position, slightly bow-in to the tow. When backing down, the bowline becomes the towline.

The stern line or turning line is lead from the tug’s stern to the outboard side of the tow’s stern. The purpose of this line is to keep the tug’s stern from drifting out. The three lines, when properly secured and made taut, will make the tug and tow work as one unit.

Note: If for some reason the stern line cannot be fair led and secured to the outboard side of the tow, it is then secured to the inboard bitt on the stern of the tow.

A fourth line (optional), the bow breast line, can also be used for greater control when making up to a heavy tow. Check all the lines to ensure that they are as taut as possible. Perform this by easing the tug forward, then aft, to see that all the towlines are secure. The tug and the tow should be made up as a single unit.


1. When securing these towlines, remember, NEVER secure the line so that it cannot be thrown off quickly and easily.

2. The tug and tow seldom pitch in the same manner. When both start pitching the lines take a heavy strain and may part. When equipped with a rudder the tow assists in steering. Size and loading of the tow may obstruct the view of the tug’s operator. In that case, a lookout is stationed aboard the top who keeps the operator informed of activity and hazards in the blind area.



The use of tugs and their connection to the tows can vary. The following are some basic types:

Single tug, single unit tow.
Single tug, multiple unit tow.
Multiple tug, single unit tow.

This consists of a tug and tow. Several methods are used in connecting the tug and tow. The single leg and bridle or stern tow is used for long distance towing in open waters. The alongside or hip tow is used where maximum control and maneuverability are required.

The single leg and bridle is made when the towing ship passes the towline, which is shackled to a flounder plate at the apex of the bridle. Each leg of the bridle consists of chain or wire rope passed through the bow chocks and secured on the tow’s deck to padeyes or bitts.

Towing alongside (hip tow) is most often used in congested waters. Towing alongside offers excellent control, it is not recommended for the open ocean. For alongside towing, the tug generally secures to one side of the tow with her own stern abaft of the stern of the tow to increase the effect of her screw and rudder. The side chosen depends on how much the towing ship must maneuver with the tow.

This consists of one tug and several tows. The connection and makeup of the tows can vary. The following are the three used for towing astern:

Christmas Tree rig (for long distance in open ocean towing).
Honolulu rig (for short distance towing).
Tandem rig (for congested waters where control is required).

It may be desirable to use more than one tug for only one tow. Greater power, increased towing speed, and better control may be obtained in a multiple tug tow. This type tow is generally used in towing large ships, deep-draft, large-displacement dry docks, or deep-draft barges.


Local apparent noon (LAN) is a sight taken on the Sun at the instant it transits an observers meridian. At that time, the Sun is at its highest altitude. The purpose of observing the Sun at LAN is that it allows you to establish your latitude.

The purpose of determining watch time of LAN is merely to enable you to arrive on the bridge within a few minutes of the time you should take your sight. Since zone time of LAN is based on your dead reckoning (DR) longitude, the exact moment it transits over your meridian will seldom be precisely calculated, but you should be able to figure it very closely.

The Greenwich Mean Time of meridian passage, or GMT Mer. Pass, is found on the lower right daily pages of "The Nautical Almanac" just below the sunset table. This is also the time that the sun will be over any standard meridian, no matter what zone you maybe in. Below is an excerpt from the Nautical Almanac that shows you how this information appears. Be sure that you use the page for the appropriate date. 12 Febuary, 1981. All the Coast Guard test question’s are based on using the 1981 Nautical Almanac.

Excerpt from Nautical Almanac time of meridian passage for Febuary 12, 1981
Eqn. of Time Pass.
00h 12h
12 1417 1417 1214
13 1417 1416 1214
14 1415 1414 1214

To compute the time of the 1st Estimate of LAN, I use a step by step process using the form shown below.

Problem 1 : On 12 Febuary 1981, your 0930 zone time DR position is LAT. 25° 20.0 N, LONG. 30° 40.0 W. Your vessel is on course 135° T at a speed of 11.2 knots. What is the zone time of local apparent noon (LAN) ?

A. 1210

B. 1215

C. 1220

D. 1224

DATE 12 Feb. 1981
MER. PASS. 1214
DR. LONG. 30° 08.0 W
d Long.(arc) 0° 08.8
d Long. (time) + 0m 32s
ZT LAN ( 1st Est. 12h 14m 32s = 1215

Step 1: Enter the appropriate date.

Step 2: Go to The "Nautical Almanac" and extract the time of meridian passage for 12 Febuary 1981.

Step 3: (a) Set up universal plotting sheet.

(b) Plot 0930 DR position and DR ahead to 1214.


- 0930

3h 44m at 11.2 knot = 41.8 miles

Step 4: Enter your DR longitude for the time of meridian passage you extracted from the almanac (1214).

Step 5: Enter the nearest standard meridian.

Step 6: Calculate the difference in arc between the standard meridian and your DR longitude.

Step 7: Convert the arc in into time using the "Conversion of Arc to Time" from the Nautical Almanac.

Step 8: Now apply the time correction to the time of meridian passage from the almanac. Because you are west of our standard meridian, you must add the difference. By applying this correction you will have the time of LAN at the meridian for your DR position. This is called the first estimate of LAN.

Note: if you clocks are set to daylight savings time (DST), add one hour to your zone time or use the standard meridian that your clocks are set to.

Sunday, February 3, 2008


A temporary eye may be put in wire by using wire rope clips. A wire rope clip consists of two parts, the U-bolt and the roddle, the part into which the U-bolt is inserted. You should always put the U-bolt over the bitter end and the roddle on the standing part. This protects the live or stress-bearing end of the rope against crushing. The roddle protects the rope and, should always be placed against the live end.
To get maximum strength from the temporary eye splice, use the correct size and number of wire clips, and the correct spacing between them. Size is stamped on the roddle between the two holes. Use the following formula to determine the number of clips: 3 x diameter of wire rope + 1 = number of clips. For example, the number of clips needed for l-inch wire rope is: 3 x 1 + 1 = 4. To determine the correct space between clips, multiply the diameter of the rope by six. For example, the space between clips to be put on 1-inch rope is: 6 x 1 = 6 inches. Measure the space from the center of one clip to the center of the next one. If the calculation for either the number or the space results in a fraction, round off to the next higher whole number.

(Molly Hogan) Splice. Sometimes you have to put a splice in fast, you can do this with the Molly Hogan splice. This splice can be quickly made, but it is limited to about 70 percent of the strength of the wire rope. It should not be used to lift heavy loads. This splice can be used only when working with preformed wire rope. To make a hasty eye splice, personnel should follow these steps:
(1) Using a marlinespike, screwdriver, or, if necessary, a nail, separate the wire rope into two three-strand sections. These sections should be unlaid four times the diameter of the desired eye. If you want a l-foot diameter eye, unlay the sections back 4 feet.
(2) Use the two sections to form a loop of the desired diameter for the eye.
(3) Lay the strands back around each other to form the eye.
(4) After the strands have been laid back around each other and the eye has been formed, seize the wire to complete the splice.

Saturday, February 2, 2008


Splicing is a method of permanently joining the ends of two lines or of bending a line back on itself to form a permanent loop or an eye. If two lines are to be spliced, strands on an end of each line are unlaid and interwoven with those of the standing part of the line. Small stuff can be spliced without a fid, which is a tapering length of hard wood used in splicing larger lines. A knife is used to cut off the ends of the strands.
Short Splice - The short splice is as strong as the rope of which it is made. The short splice increases the diameter of the rope and can be used only where this increase in diameter will not affect operation. The splice is used to repair damaged ropes or where two ropes of the same size are to be joined together permanently. Damaged parts of the rope are cut out and the good sections are spliced. These are the steps
(1) Untwist one end of each line five complete turns. Whip or tape each strand. Bring these strands tightly together so that each strand of one line alternates with a strand of the other line. Put a temporary whipping or tape on the lines where they join to keep them from coming apart. Do this procedure with small lines until you can hold them together while you tuck. 2) Starting with either line, tuck a round of strands in the other line. Then, using the strands of the other line, tuck a round in the first line. Make sure to tuck in one direction, the reverse and tuck in the other direction. When making a round of tucks, regardless of the direction, face where the lines are butted so you will always tuck from right to left. Pull each strand as to tighten the center of the splice.
(3) Tuck two more rounds in each direction. After tucking in one direction and reversing and tucking in the other direction, pull the strands as required to strengthen the center of the splice. When finished with three rounds of tucks in each direction, cut off any excess length on the strands.
NOTE: To have a smoother splice, cut off one-third of the circumference of each strand before making the second round of tucks and another third before the third round.
(4) When the splice is completed, cut off the excess strands as before. Lay the splice on the deck and roll it with your foot or hands to smooth out and tighten the splice.