RADAR

C

cod

Active Member
Joined
16 Jun 2005
Messages
59
Visit site
Just got in. Thanks for the replies to my post this morning. Very poor internet connection so will make a few short posts. Very annoying when you have typed a humungus post struggling with 1 finger to get cut off when just about to press send.

MINESAPINT
 
Firstly sorry I omitted to include the range which is 2M. The vessel on the starboard beam is directly on the beam. 90 degrees to starboard relative to our course.

MINESAPINT
 
Clearly the rule we should be interested in is 19. Conduct of vessels in restricted visibility.

19 d i avoid an alteration to port for a vessel forward of the beam etc

19 d ii avoid an alteration towards a vessel etc.

MINESAPINT.
 
However I have come across a rule of thumb as follows

Draw a circle to represent a radar screen put in your vessel heading at 0 degrees. Draw a line from the centre to the circumference at about 80 degrees, draw another at 190 degrees. This gives a small sector and a large sector.

The rule of thumb states that you should alter to starboard for a target in the large sector and to port for a target in the small sector.

MINESAPINT
 
Minesapint... I drew that exact circle and sector in my almanac next to rule 19... its a good simple rule to follow.....

For what its worth....my initial thought, without further information would be to observe carefully for a couple of minutes to check that bearing remains constant, and to assess the rate of closing..... if it remains constant, then we can assume that we have a vessel following a converging track on our starboard side that has a collision point sometime in the future. If the closing rate was rapid, then I would execute a large turn to port to allow vessel to pass ahead of us and on our starboard side... if the rate was slow, I would execute a large turn to starboard and pass behind his stern/port to port before re-establishing my course..... the safest option will be the turn to port, but I guess other shpping might influence it...
 
If you study rule 19 and the rule of thumb you will see there is a conflict. I have been taught the rule of thumb by a very experienced RNLI Coxwain and RYA Yachtmaster Examiner.

However in the question an alteration to port would agree with rule 19 as the target is not forward of the beam it is on the beam. It would also agree with the rule of thumb.

MINESAPINT
 
The interesting thing is that the question is straight out of the RYA RADAR Course book page 26. It is a multiple choice question. The choices are

1 alter to starboard
2 stand on
3 slow down or stop

MINESAPINT
 
Ah...... all wrong according to rule 19...... the only guaranteed safe one of these 3 is slow down or stop..... alter to starboard could be OK, but not guaranteed...but needs other info for certainty... also, I would prefer not to slow down or stop in a heavy sea, or in a shipping lane.... and besides if the visibility is crap, you should be going reasonably slowly already, and so it might not have the desired effect if the closing speed is very high.... HSS out of Harwich for example could be doing 40kts.....
 
If the other vessel had radar it would alter to starboard according to the rules and the rule of thumb so if we alter to port all is well.

MINESAPINT.
 
answer

of the choices given i think the answer is turn 135 degrees or more - almost turn back on yourself to put the thing on port quarter passing behind your stern .... Because

1 it's an rya question so you ALWAYS are in a westerly 29 footer with crap engine and no gps chart plotter.

2 they have this thing about not stopping

3 you can't "stand on" in fog

4 it's 2 miles away so ok to turn inside him at decent range

BUT dependsd on lots of other things. like if in tight sealane can't ponce about like that. and so on
imho
 
Would agree the 'rule' is generally good and avoids uncertain decisions on a beam closing target.

But your post was economical, and given sea-room I would always alter to stbd knowing that my temporary adversary on the other bridge would think alike. Force of habit, and still here to tell the tale.
 
Keep your eye on the blip on the radar, and keep out of the way.
A french boat on sunday {faster then me } was on my bow, I kept my course, he past me on my starboard side, SOD the collision RULES!
And in good visability.
 
I am easily confused. I thought under these circumstances you should have altered to starboard, not held your course.

Rule 14 a

MINESAPINT.
 
would agree! - if in your opinion a risk of collision existed.

it would appear it didn't to you, and surprisingly not to the other skipper ( /forums/images/graemlins/wink.gif) so you both held course and passed..........
 
You must log in or register to reply here.

Share this page

Top