Can I Port a Single Line From a Family Plan

Heavy traffic, extra Wait out posted, hours of darkness. Suddenly the GPS is gone !!! Ever experienced this ?

Believe me when it happens, you start doubting each and every equipment. Even the ones which may exist working fine at that moment.

Is the gyro giving correct heading ?  Is the echo sounder showing correct depth ? You will dubiousness everything !!! That's non good.

You will loose the sense of direction. And you lot would have tiny amount of time to regain the sense and human activity in a way that is right.

The entire navigation depends upon knowing the position of the ship. This is i of the nigh important task of a navigator.

But when I say position, I practice not only mean GPS position. There are many other ways of plotting the send's position. And as with the situation of GPS failing, we must exist set up to switch to other methods of position fixing.

Before nosotros proceed with discussing these methods, I must discuss a term which is so much a part of passage planning. The term is "position Fixing Interval".

Position Fixing Interval

"Position fixing interval" is the maximum interval betwixt 2 position fixes. So if in a detail section of the passage, we have agreed to the PFI of 01 hour, we must plot the transport's position at least every hour.

But how do we decide the position fixing interval ?

For that just call up why do we need to plot the position ? We plot position to be sure that we are on our track and not drifting towards a danger.

With that logic in mind, allow u.s.a. take an example.

I plot a position at 0800 Hrs. The agreed position fixing interval is 30 minutes. Now simply after 0800 Hrs, the vessel starts to draft straight towards a danger.

I will only come to know about that at 0830 Hrs when I plot the side by side position of the ship. If at 0830 Hrs, vessel is at the danger so the PFI was set too loftier.Considering before we could know that we are running into danger, we already were at the danger.

So even if vessel deviates from its course, the interval between 2 consecutive position fixes should exist such that allows time to accept the course corrective activeness.

Method of position Fixes

In that location are many methods by which nosotros can become a ready of the ship's position. Some of which are

• Celestial prepare by using sextant
• Visual ready
• Radar Fix
• GPS
• Repeat sounder
• Parallel Indexing

Primary method of position fixing

1 of the element of passage planning is to identify the primary and secondary method of position fixing at each leg of the passage.

At that place should always exist at to the lowest degree ii method of position fixing.

Now at open sea, the primary method is GPS and secondary method would be "angelic prepare".

If at that place is a radar conspicuous object, the primary method of position fixing becomes the "radar fix". Secondary in this case would be GPS.

Now if that object is also visible, primary method becomes the "Visual fix". In this case secondary method will be "Radar fix".

The idea is that Visual fix gets the highest priority followed by radar fix. And radar set up gets the priority over GPS.

On tankers the vetting inspectors expects that if available visual and/or radar fixes must exist plotted at least for the PFI.

For example let u.s.a. say that the set PFI is ten Minutes and the agreed position fixing method is Radar and Visual fix. Let us say we plot position at

• 0900 Hrs: Radar or Visual Fix
• 0910: Position past GPS
• 0920: Radar or Visual Fix

This is considered to be wrong and would draw a vetting observation as the radar/visual position is plotted subsequently 20 minutes where every bit PFI is 10 Minutes.

Celestial Gear up using sextant

This method is not so popular during littoral navigation because of few reasons.

One considering this method requires some time to know the position because of calculations involved.

Second because in that location are chances of user induced error (similar fault in taking the sight). That may non be so nice when send is navigating in the proximity of dangers during coastal navigation.

But there is a gross misconception virtually this method amongst many seafarers. Misconception is that position by angelic observations are non accurate.

Instead, if nosotros can have our easily fix perfectly to have accurate sextant altitude, the position obtained past this method are quite accurate.

There are few disadvantages with this method.

Even though this method exercise non rely on electronic equipments and satellites just it need nature in our favour.

Nosotros demand clear sky and articulate horizon so that we can measure out the altitude of the celestial body.

Even when the sky is clear, information technology is difficult to measure the sextant altitude when send is rolling.

"How to use sextant to get the transport'south position" is as well large a topic to fit in this postal service and I will write on that in item on some other day.

Position by GPS fixes

Practice I demand to say anything about GPS fixes ? Even the supernumaries on board know how to plot GPS position.

This is most over relied method of position fixing. Over relied for a expert reason. It is Crisp accurate (nigh of the fourth dimension) and quick fix.

On Mod ECDIS, navigators do not demand to exercise anything in plotting the GPS positions. These are plotted automatically at the ready interval.

Some ECDIS can even tape the ship'due south position when it senses alter in whatever parameters like change in course.

For the passage planning we must ensure that PFI is set in the ECDIS, so that GPS positions are marked and recorded automatically in the ECDIS.

To set the PFI in furuno ECDIS, go to DISP -> Fix -> then choose Symbol DISP.

Now become to Tracking. The Position fixing interval can exist prepare under Labels. Once fix, the GPS position will be recorded at the mentioned interval.

GPS fixes are accurate, no doubt about that. The only issue with GPS fixes is the Self-approbation and over-reliance. Over-reliance to the extent that we may find ourself unconfortable if the GPS fails.

Radar Fixes

Position by radar gives quite authentic results and must be used whenever we have radar conspicuous objects.

The advantage with radar fixes is that information technology just needs one object to get the ship's position. We tin get the range and bearing of this object and plot the aforementioned on the chart.

For example let usa say nosotros get the begetting of this lite every bit 050 degrees and range as 4.four NM.

We will draw a line of 050 degrees to this lite. We will so mensurate four.four NM on the compass and cut the bearing line with this distance.

In the aforementioned way, if y'all accept ii objects, you can plot the radar fix by number of combinations of position lines like

• bearings of these two objects
• begetting of one object and range of other object
• range of both objects

Equally more than and more ships are moving to the paperless navigation, we must know how to fix the transport'south position by radar on ECDIS.

So let us ready the ship'south position on Furuno ECDIS.

Allow united states of america say for this island, we get a bearing of 010 Degrees and distance 2.5NM from the radar.

On Furuno ECDIS go to Record -> This volition open a position event window. Choose LOP and then choose True-bearing + Distance option.

At present click on the point of the island for which the bearing and distance were taken from the radar.

At present enter the begetting and distance in the position event window and and so click "Add".

This volition requite you your position.

Now if you wish to record this position in the memory of ECDIS, click "Tape" in the position outcome window. The position will be plotted on ECDIS and recorded in the memory.

If nosotros have two bearings (or two range) of two objects, the process of plotting radar fix on ECDIS is aforementioned equally to a higher place. Just instead of "bearing + Distance", choose "bearing" (or distance) option.

Visual Fixes

Visual fixes are least practiced position fixing method inspite of being authentic. All information technology requires is a visual target and compass for taking its bearing.

Position past Visual bearing of ii objects

If we have ii objects that are visible from the send, the bearing of these 2 can become united states of america the ship'southward position.

For a meliorate accuracy of position by two bearings, the two bearings should neither be too narrow nor too wide. Separation angle close to 45 degrees being the ideal one.

To plot the position by visual bearings of 2 objects, take the bearings of both the objects simultaneously.

At present draw the begetting of these objects on the charts. The point where these two bearings (position lines) intersect will exist the ship's position.

How to do this on ECDIS ?

The procedure is same what we did for plotting radar gear up on ECDIS.

Position by Running Fix

Even when there is only one object visible for visual bearing, we can still go the position. The method is called "running set".

In this method, we take the beginning bearing of this object before when it is forward of our beam. Let united states say we see a light Fl 5s 20m 16M. At 2000 Hrs nosotros have its bearing and information technology comes out to be 020 degrees.

Plot it on the chart. This is the first position line at 2000 Hrs.

Take the second bearing of same object when it is abaft the axle. Say this time we take the bearing at 2020 and the bearing is 300 Degrees.

Plot it on chart. This is the position line at 2020 Hrs.

Now we have two position lines only both are at different times. We need to bring either of these position lines to the same fourth dimension as the other one.

How exercise we do that ?

We know our grade made proficient and speed, plot the this on the chart. Now on this course line cut the distance covered in 20 minutes which is the interval between 2 position lines. Let us name this point as point A.

At present transfer your first position line to the betoken A. The betoken where it cuts the 2nd position line is the ship's position at 2020 Hrs. This is because at present both the position lines are at same time.

To get the position at 2000 Hrs, depict your form made practiced from the 2020 Hrs position. The betoken where it cuts the outset position line volition be the send's position at 2000 Hrs.

How to get running fix plotted on ECDIS ? Let united states plot this on furuno ECDIS.

We take the kickoff bearing of the fixed object and we plot first position line on ECDIS. To practise that from the left menu options become to Record -> Event log -> Posn issue.

This will show a pop upwardly chosen position issue.

Mark the first position line of the stock-still object that you accept taken the visual bearing from and click "add" to add the position line.

Now when you have the second bearing of the same object, mark the 2d begetting on the ECDIS in the same way. Brand sure the pick "transfer off" is slected while marking both the bearing.

Then we have the two position lines but both are at different times. Nosotros need to transfer the 1st position to the present time to get a fix past "running fix" method.

To practise that, choose the position line number 1 from the position outcome popular upwardly (under LOP observations).

And then change the option to "Transfer to latest".

Once nosotros cull "transfer to latest" option for position line # 1, this position line will exist transferred to the latest fourth dimension. You will besides see TPL marked on this position line which denotes "transferred position line".

The position where information technology cuts the second position line is the ship'southward position.

The position where it cuts the 2d position line is the transport'due south position. To record this position in the history data of ECDIS, just click on "tape" selection in the "position event" pop up. This will mark the ship's position on the ECDIS and save it in the history data.

Position by Repeat Sounder

I am sure not many discuss this as the position fixing method. Rightly so. We accept and so many resources and we do non need to rely on echo sounder for position fixing.

Simply as I said, when the GPS fails we start doubting everything and each equipment. More methods of reassuring u.s.a. about position tin can be handy.

Echo sounder cannot be used equally a position fixing tool only it can be used to confirm the known position of the send.

Have a look at this photo. This could be i of the identify where we can ascertain our position by echo sounder.

If nosotros meet depth of around forty meters on echo sounder and at the same time nosotros take bearing of the edge of the island that is visible to us. We draw position line from this isle.

Every bit in that location is only one point on this position line where the depth is expected to exist effectually xl meters, this volition be our estimated position.

As I said this is not the position fixing method. But we tin can utilize this as a confirmation tool for the position we become from other methods.

Parallel Indexing

Nosotros earlier discussed that the interval between 2 position fixes should be such that betwixt whatsoever two fixes, the vessel must be safe.

But this would hateful that during arrival into a port, we need to plot our position every 60 seconds.

Many, including some third party inspectors may insist on this just this is crazy. Imagine plotting the radar fixes every two minutes.

Sometimes even the chart would not be of such big scale that can distinguish the two positions plotted at two minutes interval.

I feel PFI of less than v minutes is not practical. Then how exercise nosotros ensure transport does not come across danger if PFI need to be less than five minutes and we plot the position every 5 minutes ?

The respond is by "parallel indexing".

We place a stock-still object and draw a line parallel to our class. We and then monitor the echo of this object on the radar.

If the repeat stays on the line drawn parallel to the class, we are on our course. If the echo deviates from the line, we are off rail and we must alter the course to bring the vessel on track.

This is a method which ensures continuous monitoring of the send'southward position.

In the situations where PFI comes out to be less than 5 minutes, we can gear up the PFI as 5 minutes and then monitor the ship's position past parallel indexing and plotting the position every 5 minutes.

Parallel indexing is a fantastic tool for monitoring the ship's position. For this reason, it must be used wherever a radar conspicuous object or landmark is available.

Determination

In that location is one basic requirement that a navigating officer on watch need to fulfil. At all times he must know

• Where we are, and
• Where they (other targets) are

Sadly most of the groundings happens considering we either practice not know one of these or both. If we know all the methods of plotting and then confirming our position, we will never miss out where we are.

With now more and more ships going paperless, we must also transform ourself to be able to use these methods on ECDIS.

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Source: https://www.myseatime.com/blog/detail/position-fixing-the-most-important-element-of-passage-planning

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