wonderful explanation! I have just learnt how to do these and I just need to confirm how the speed is calculated when you go from the NRML and choose to slow down....in your example you showed 6 knots - please tell me how you arrive at this - is it the distance over same time period from R - M ?
Leon, I'm glad you liked the explanation and the video. To determine the new speed of your ship to create the new relative motion (NRML) you measure the length of the ownship vector in the triangle from "T" to where the NRML line crossed "T" towards "r'. In practice, you measure up the vector, from "T" towards "r". As you are going up the vector you will encounter where the NRML line crosses the ownship "T" vector. In the video example its about halfway up. If your original speed were 15kn, you might measure 7.5kn at the crossing of the NRML past "T" Thus you would need to drop your speed by half, down to 7.5kn as the contact approaches "mx" and it would slide down the NRML. Good day and...keep on plottin' GB
Thank you Mr George. I watched your video a few days ago before I went to renew my radar. It was very helpful and was able to pass my test with no problems.
Greetings Mr. Burkely Very nicely paced revision presentation. When I follow the construction on plain paper (scale 1":1nM) and calculating separately by trigonometry I get Course to Steer 39.5°T and Speed Reduction solution at a beeswing under 4 knots. Your own new course to steer of 31°T looks very small to. produce the desired change in target's NLRM. I wonder if you have a comment or suggestion. Thanks JR.
wonderful explanation! I have just learnt how to do these and I just need to confirm how the speed is calculated when you go from the NRML and choose to slow down....in your example you showed 6 knots - please tell me how you arrive at this - is it the distance over same time period from R - M ?
Leon, I'm glad you liked the explanation and the video. To determine the new speed of your ship to create the new relative motion (NRML) you measure the length of the ownship vector in the triangle from "T" to where the NRML line crossed "T" towards "r'. In practice, you measure up the vector, from "T" towards "r". As you are going up the vector you will encounter where the NRML line crosses the ownship "T" vector. In the video example its about halfway up. If your original speed were 15kn, you might measure 7.5kn at the crossing of the NRML past "T" Thus you would need to drop your speed by half, down to 7.5kn as the contact approaches "mx" and it would slide down the NRML. Good day and...keep on plottin' GB
Maritime Pilots Institute
Thank you Mr George. I watched your video a few days ago before I went to renew my radar. It was very helpful and was able to pass my test with no problems.
Thanks for this detailed explanation!
thanks for the video...it helps me a lot. :)
Greetings Mr. Burkely
Very nicely paced revision presentation. When I follow the construction on plain paper (scale 1":1nM) and calculating separately by trigonometry I get Course to Steer 39.5°T and Speed Reduction solution at a beeswing under 4 knots. Your own new course to steer of 31°T looks very small to. produce the desired change in target's NLRM. I wonder if you have a comment or suggestion. Thanks JR.
My board looks nothing like this one
Thumb down for promoting poor radio protocol referencing own ship and not the vessel being hailed, as best practice calls for in this situation.
That is how it is referenced in USCG Questions for Radar plots, so that is why the reference own ship and contact as the other ship.