Radar Plotting: Complete The Plot

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---------ABOUT THE VIDEO---------
This video was originally uploaded to our other channel, Casual Navigation, back in 2018.
In this video I show you how to complete a radar plot to find the CPA, TCPA, Course, Speed and Aspect of a target vessel.
Learning how to complete a manual radar plot is an essential part of any maritime training, whether you are learning to navigate a supertanker or a sailing yacht. Knowing how the electronic equipment performs its calculations is vital so that you can understand its limitations.
---------DISCLAIMER---------
Although we take all reasonable care to ensure the accuracy and reliability of the information provided in the content on this channel, the content is provided “as is”. We do not make any warranties about the accuracy, content, completeness, legality or reliability of the information contained within this channel.
The information contained within our videos is not professional or legal advice and should not be considered as such. If you need professional or legal advice, you should consult a suitably qualified professional.
Any action you take as a result of watching this video is strictly at your own risk.

[@irshaadkhan6378]

Exactly 1 year ago passed my electronic navigation system exams all because of watching your videos. Thank you so much for this!

[@BeginnerCyclistNetwork]

Right, this is probably the 10th video I've watched on this this evening. This is the only one that made sense to me. Thanks.

[@marinefaqts]

This was so helpful. Request making a video for True motion plotting. Think it's a wee more complicated than Relative

[@theirishanime007]

Thanks bro! Really helped me understand!

[@ronanboyle1338]

Great material and easily understood in all your videos

[@Wil_Sailor]

Thanks it helps me a lot for doing my activities during this Online class❤️

[@paterson00]

This was a very interesting video. My first foray into radar plotting. Thanks for creating. I expected you to stop once you completed the ColRegs so I'm pleased you've more to share. Passed my Coxswain last Friday!!!

[@CasualNavigationAcademy]

Congratulations Paul! That's fantastic news. I have a few radar plotting ones, then will be onto my celestial navigation videos. After that I'll be making new ones when I can. I am excited for this channel as I can just put up all my maritime animations without worrying about the youtube algorithm any more

[@paterson00]

That's great to hear as your format is great. Very easy to follow and breaks things down nicely. I'll continue training for more qualifications and know that I'll use your videos to help so thanks again. I'll be chasing sailing qualifications next. RYA competent crew first then day skipper so i can go and charter a sailboat for family holidays

[@kenlee-97]

​@@paterson00oh-oh... Just kidding...

[@OranTeach]

Cheers mate ❤️ Really good explanation

[@margaritakoufou4816]

Thank you!

[@elenapeconcillo6950]

NICE VIDEO!! NICE CONTENT!!!

[@CasualNavigationAcademy]

Thanks Elena. Glad you liked it

[@sudman21]

Thanks a lot

[@srinivasrao9702]

ThNk you sir

[@blahblah55555666666]

fantastic

[@jamesjunior5560]

Radar Plot Easy to Understand Summary by M Doyle. 1. The range rings have got to be represented as a ruler on the side of the plotting sheet divided into units - the best one is if the radar has been set to miles with an overall range of 6 miles - each ring is a mile, and we draw that as a ruler against the side. The inner unit miles can be divided into parts - but those parts are not miles just units of each mile. So, the ruler is a side representation of the range rings - that’s all - just for measuring plots and distances more easily. 2. Drawing in your own vector from the centre of the range rings - your distance travelled and direction - is next. 3. Marking in on paper the actual plots of the incoming vessel/s that you are viewing on your screen. The above are the first three steps. In the first instance, we only know the range and bearing of the target vessel. We know it is six miles away as it appears at the outer edge of our range rings - and we can see on the compass the direction it is from us - its bearing. To immediately find the CPA - we joined a line straight through the middle of three plots - where it passed us at the closet point is the ‘CPA’. If that line goes straight through us, then we call it zero. Now we move on to TCPA - to “find out how long until that collision’ calculating time to go until the collision - remaining distance (to you) x overall minutes of plot/s taken (e.g., 12 minutes) divided by distance of target vessel so far travelled (ratio). So, we first work out how far it has travelled in the 12 minutes that we have been plotting it. By figuring that out we can work out the time it will take to complete the journey to us. So, we grab the distance travelled (using the ruler) - then grab the distance to go (using the ruler) - it is not the total of the range rings as we are moving relative to it - these two figures are our ‘ratio’ - we know the math now - distance to go (between us and incoming vessel) x total minutes of the plots, divided by distance travelled so far (of incoming vessel). We get the number of minutes left to the CPA which is our TCPA. So, we can now write this by the side on the plotting sheet: CPA TCPA Then we move on to discover the target vessel’s: Course Speed He labels the incoming vessel first plot position as O (first position) and A (Final or Actual position). The moves are as follows: 1. Drawing the Vector of your own vessel as a line extending away from target vessel’s first position (O). Using your known heading. North makes it very easy. You draw the line away from the target vessel the length of your vector (your calculated distance based on speed over the plot time elapsed - as per 2 above). 2. Labelling the top and bottom of that vector ‘Way of Own Vessel’ vector as W and O (the O is for original) - has already been labelled. (W) at bottom) 3. A will be added for final plot position if not already labelled. (Actual) 4. Joining the W (bottom of your vector) to the (A) to provide another vector. (Way of another) 5. Sliding that vector (WA) back to the centre and extending it out to the edge (of the compass rose) to get a course of target vessel. (I call it - ‘the back slide’) 6. Calculating the speed in knots per hour (of incoming vessel) by measuring the distance of the vector W A and multiplying the minutes travelled (overall plot time e.g., 12 minutes) and the distance (by the same amounts) to get an hourly read off. e.g., 1.1 in 12 mins becomes 5.5 in 60 - speed = 5,5 Knots. See how 1.1 and 12 have been multiplied by 5 - that is what I mean when I say ‘multiplied equally’). 1. Bearing - their bearing is their compass direction from us - not their course. Obviously, if their closet point of approach is zero, they will not bear away from us at the CPA - but if their CPA is say ‘1 mile’ - they will bear away from us in one direction or the other. Looking at this in a more detailed plot later. 1. Aspect - Move the target vessel’s vector (WOA) onto their ‘A’ Actual position. It was their vector bearing minus our reciprocal that equalled the Aspect- labelled as red if port side. The Aspect is just, as best I can make out, a measurement of degrees that we are angled off the target vessel. It really should be obvious whether we are on the port or starboard side, but it is by how many degrees that we are looking for accuracy. So, we deduct our bearing from the vessel from their heading. Not well explained or easy to understand - needs greater clarity but makes sense at the end of the video when the real-life ships are presented under the plots.

[@godmakesmeafilipino5280]

What is the new course of red vessel when it changed its course and how it computed?? thanks.

[@Saga47swanSailing]

Hi , great video - aspect ..... red 78 ?? Why red , we have the other vessel at 78 deg , it is on our starboard side . Is it red , because we are give way vessel ? Thanks

[@keithjasonabonitalla4477]

Pls make a new video!!! More vessels in plotting

[@ocelot6755]

Hey why was this removed previously? I notice you repuloaded it.

[@progamerz7236]

How do i know where to plot when i only get the bearing..

[@officerpalma156]

Still best letter to use in vector triangle is e - r - m..... for ur rml erm drm srm........

[@kenlee-97]

D-u-m...

[@59patrickw]

will we get to the point ware we have multiple vessels on the screen

[@CasualNavigationAcademy]

I like that idea. I have been working on a better radar animation so would like to do more when I can

[@59patrickw]

@@CasualNavigationAcademy thank you for the reply i like what you are doing and the way you do it , you don't talk down to us in youtube land

[@vkmariner2371]

Target vessel heading 150 and own is 000,saw the target vessel 30 degree on port bow.what will the aspect?

[@temmon8493]

I guess 120° for the aspect