Radar

[Tony Wilding]

HI, i often read of Radar assisted collisions, ? can someone tell me how this can happen, in laymans terms, am completely in the dark. tony wilding.

[Mike Line]

There are 2 ways to view a conventional radar screen, Ships Head Up or Relative Motion.
Ships Head Up is the older and was the usual view used by many, especialy the "older" members on the bridge. As it says, the radar screen has a solid pointer on the fore and aft line of the ship, port is port, stbd is stbd, and the ship stays fixed to the center of the screen.
Relative motion, is similar to the view of the ship as it moves across a ships chart, ie North is the fixed point, with the ship moving accross the radar screen, in any direction, relative to its compass course.This view is sometimes prefered.
Radar assisted collisions or near misses normaly occure using SHU. The officers brain and the radar do not always inergrate, a ship that appears to be on a parrallel course may in fact be closing, a crossing vessel may be doing the same thing. It is normally solved by plotting the relative courses this a chinograph pencil on the radar screen and joining the dots.
I have not heared of a Radar assisted collision using Relative Motion, but it has probably happened.
I do know of a near miss, caused by a more senior officer switching from one view to the other and not informing the watchkeeper.
A good lookout normally resolves the problem.

[Gulliver]

HI, i often read of Radar assisted collisions, ? can someone tell me how this can happen, in laymans terms, am completely in the dark. tony wilding.

I’ll try Tony.
Briefly it means that by using the radar,one or both ships)actually collided with each other.
It sounds daft,but if the ships weren’t fitted with radar (as in years gone by) they would(should !) have been following the Collision Regs.with reference to such regulations as proceeding at a moderate speed,stopping and reversing engines and listening for fog signals etc and not proceeding until absolutely certain of the position of the other vessel. They would not therefore normally have collided.Radar has limitations,especially if wrongly used or the information on it is wrongly interpreted by the observer.
Especially in the 50’s and 60’s when radar became more and more common on merchant ships,Masters thought it would give them the ‘edge’ over other vessels ,in being able to ‘see’ them. They thought they could rely on it more,and the other provisions of the Rules,safe speed.lookout etc took second place.i.e. they gave the Master an excuse not to slow down and therefore maintain schedule.Things got better as True Motion radar and other enhancements came in.as well of course the requirement that all Certificated Deck Officers were trained in their use. I don’t think (at least I hope not) that they happen too much these days !

Notable ‘radar-assisted’ collisions were the liners Stockholm and Andrea Doria off New York in 1956;the Shell tanker Sitala and the Niceto de Larrinaga ;and,the British Aviator and Crystal Jewel,both in the English Channel in 1961. All these with tragic loss of life.In all cases it was a slow but steady alteration of each vessel (I think they call this 'the accumulated turn' )to ‘open’ the bearing between them and give the impression that they had a safe passing distance between them.It was found that far from being on a reciprocal course,they were actually on converging courses up until the last minute,when drastic course alteration had to be applied….too late. In the case of the Andrea Doria and the Stockholm,if plotting had been carried out at the distance they were first observed on radar and a relative plot been carried out at regular intervals it would have been apparent of each other’s course and speed.This was not done on the Andrea Doria,and the Stockholm could not see the Andrea Doria visually anyway,because she(the Stockholm ) was in a fogbank…it was also found that Stockholm’s radar was on a much shorter range than should have been,and could not have detected the Andrea Doria….. or been plotting her.
Hope that explains a bit,doubtless others will try to explain more succinctly and thoroughly,but that basically is what a' radar-assisted collision' is.

Gulliver

[John Cassels]

All the best radar assisted collisions occur in fog , mist falling snow, heavy rain or any other conditions
similarily restricting visibility.
The most notable are when each vessels sees the echo of the other fine on the bow - especially port bow.
Each thinks a small alteration of course to " open up the angle" will be enough. One of them will alter to
port and the other to stbd. usually by small amounts. This small amount will not readily be noticable to
each other and they will alter a little more - the already mentioned cumulative turn.

There collisions are well documented and the basic way to avoid is a large alteration leaving no doubt in
the other guy's mind as to waht is being done.

[j.sabourn]

All these good intentions re use of radar are ok. If one still obeys the Rule of the Road. For example what does one do in the middle of a fishing boat fleet. I s impossible to plot about 100 targets at the same time. In some cases is best to switch radar off and let watchkeepers and lookouts use their eyes and ears and do what one did before Radar. If you have a collission with the radar on in these circumstances it would be classed as a Radar assisted collission. The present day watchkeepers that I have seen spend all their time with eyes glued to Radar even during clear weather, they have obviously been brought up with it and know no better. God help shipping if we ever lose the modern aids. J.Sabourn

[Louis the Amigo]

Hi shipmates did any one on this forum sail on any ships with early radar {wartime} or just after? please post with details thanks

[John Cassels]

Hi shipmates did any one on this forum sail on any ships with early radar {wartime} or just after? please post with details thanks

On my first couple of ships as apprentice - early '60's - the radar was the old Decca mk4 which I
believe was wartime or shortly after. Unfortunatly it was so long ago , can't remember much detail.

[Louis the Amigo]

Hi Shipmates. Hi John Cassels, Thanks for your reply I would like information on early radar because I have a R.A.F. boffins note book {wartime} with diagrams and notes about the new system of radar !!! and how it was used on the coast spotting planes and shipping , the people who experimented with it then , and who manned the radar towers? R.A.F. men are very thin on the ground from that time, and it was very hush hush so I have been informed ?

[Tony Wilding]

Thanks for explanations on radar assisted collisions, it seems a case of disorientation, of the operators in relation to ships true courses on a collision course, expect a much clearer picture is obtained by a fixed position radar, i.e. Dover coastguard monitoring 2 ships on a converging course, thanks to all. Tony wilding.

[John Cassels]

Tony , it's more a lack of appreciation as to what the screen is telling you.

One of the cases I was refering to concerned two tankers off the SA coast. They were on NEARLY
opposite courses but slightly converging. One saw the other on her starboard bow and the other the one
on her port bow. Both altered by 5 deg to give the other more room but all the first ship did was alter
into the second ships course. Very easy trap to fall into with small alterations , lack of radar
appreciation and a lack of proper plotting. Both thought they were on opposite courses which was not
the case .
The situation ended up with a number of small alterations by both ships , one always to port and the
other to stbd. By the time both realised what was happening , it was too late to avoid the disastrous
collision which then took place. they only saw each other when a couple of cables away.