Radar or VHF Assisted Collisions

[Refueler]

Where did it come from ?

A combination of Screen Burn and also Magnetron life.

Early magnetrons had relatively short lives compared to later and it was common to open a box and find Radio Officer had kept old ones with label : "Old but working" .......

Screens of course were same as the old black and white TV's .... CRT's

 

[Carib]

Some great stories above!

Some may have heard of 'Perisher', the Submarine Command Course. Watching those guys in action holding a three dimensional tactical picture in their heads whilst prosecuting a contact and avoiding counter attack is awesome. Armed with two stopwatches and brainpower. I learnt masses about decisions under intense pressure from those guys, my Captains.
Really helped me understand relative movement when messing about in small craft. ?

On the Perisher, I thought I'd seen a documentary about that quite recently, but I can't find it. I did turn up this documentary on Perisher from the 1980s, which looks worth a watch..

 

[PilotWolf]

Where did it come from ?

A combination of Screen Burn and also Magnetron life.

Early magnetrons had relatively short lives compared to later and it was common to open a box and find Radio Officer had kept old ones with label : "Old but working" .......

Screens of course were same as the old black and white TV's .... CRT's

THe USCG radar training manual is so old it still refers to CRTs!

i seem to recall the Perished series too.

Anyone remember Warship - fiction but loved it as a kid. Not sure if it available over there but an quite good one that is quite good is Australian - ‘Sea Patrol’

W.

 

[PilotWolf]

Where did it come from ?

A combination of Screen Burn and also Magnetron life.

Early magnetrons had relatively short lives compared to later and it was common to open a box and find Radio Officer had kept old ones with label : "Old but working" .......

Screens of course were same as the old black and white TV's .... CRT's

Further to my earlier lost one of the boats had the ‘standby‘ screen burnt into it! The bigger boats had a captain and 2nd - also qualified as captain. I was appalled at the lack of knowledge regularly complained to management about it After I lost my job bled on my unreliability due to my injury. I’m pretty sure that the safety complaints were the real reason

PW.

 

[Refueler]

THe USCG radar training manual is so old it still refers to CRTs!

i seem to recall the Perished series too.

Anyone remember Warship - fiction but loved it as a kid. Not sure if it available over there but an quite good one that is quite good is Australian - ‘Sea Patrol’

W.

Sea Patrol was good till they got the New Ship and then it got a bit boring ...

 

[Kukri]

Helped by the “no lights” evidence, but by the 90s surely they should have been keeping a radar watch?

Pete

“... by all available means..” Yes; the Master’s attitude was considered out of date even then

 

[Kukri]

Helped by the “no lights” evidence, but by the 90s surely they should have been keeping a radar watch?

Pete

“... by all available means..” Yes; the Master’s attitude was considered out of date even then.

 

[capnsensible]

Some great stories above!



On the Perisher, I thought I'd seen a documentary about that quite recently, but I can't find it. I did turn up this documentary on Perisher from the 1980s, which looks worth a watch..

This is more up to date.

Regarding the first one, I knew a loada people in it!

 

[Carib]

Thanks - that's the one. Seems to block me from viewing it though on Copyright grounds.. I might watch the original!

 

[PilotWolf]

Sea Patrol was good till they got the New Ship and then it got a bit boring ...

Kind of fancied the Captain

W.

 

[Uricanejack]

Did they ever advance a reason for it? Preserving magnetron life / scanner bearings / etc, or just “newfangled nonsense” attitude?

Pete

It was a common misunderstanding back in the days of yore, if you left the radar on all the time, it would get worn out and not be available when needed.
Trying to explain to some Capt 30 years senior to you, what he believed was in fact a myth, was unlikely to go well.
Ironicaly truth was turning the old valve and tube CRT radars on and off caused them to fail by blowing tubes much more quickly.

When I first started out with an oil major, it was standard practice to leave them all the time on at sea, at anchor for any length of time the brilliance could be turned down to prevent the tube getting burnt.
In Port they were turned off, Due to the risks of cargoes operations. Can’t say I am aware of any occasion a radar being left on was the cause of an explosion , didn’t want to be the first. Needless to say policy was pretty strict.

When I moved on to other pastures, I met some old chaps who had an older belief system, my opinion wasn’t going to have much effect on theirs, if I was ordered to turn it off, I shrugged and complied.
As I got older, And more experienced, I got more difficult. Looking back to why I complied so easily, There was often a less than subtle implication, if I couldn’t keep a watch with out the radar my competence was questionable. Which caused my more difficult tendency to kick in.
One particular old guy, quit bugging me about it, when I came round Ushant into the Channel with out it,
when He asked why,
I pointed out his standing and night orders, required me to leave it off until, he was informed it was needed.
I didn’t need it yet.
He amended his standing orders.
When I was a lad, Quite a few of the AB’s I sailed with, Were Ex RN.
Somebody, gives you a stupid order? Comply
Yes, I have actually seen a QM with a big grin turn a ship 350 degrees.
Leaving a rather embarrassed, OOW to explain why.

 

[Uricanejack]

We got on the bridge of Stena Explorer Holyhead to Dun Laoghaire doing around 40 kts. When I asked how much they slow down in fog, the reply was they have a schedule to keep so don't.

In one of my former incarnations, I worked for Stena. I can’t speak for those guys.
Just my own personal experience. As OOW. Yes I had a schedule to keep, I was expected. To arrive on time, or have a good explanation.
Restricted visabilty. On my route was a common occurrence as was TSS, Narrow Channel, Pilotage Water,(exempt) Lot of comercial traffic, comercial fishing, sport fishing, sailing, yachting, even kayaks, Never did see a paddle board with Stena.
Bridge team 99% of the time single OOW plus lookout, plus Auto. stand by look out on Call, QM plus Look out when in restricted vis.
Early Generation ARPA, S &X band plus reflection plotter, plus slave non approved ARRPA With day light screen(Nice)
Twin Bridge control CPP. 10000 GRT 22 knot.
Lots can be said about Stena. I liked working for them, not everyone did.

I can honestly say, I never at any time felt under pressure to put the schedule ahead of safety particularly safe speed from the company or any of the Masters I worked for.
I had to explain why I did not arrive of the dock presisicly when required

All I had to say reduced speed for reduced visibility between A and B plus times.

My speed would vary greatly in reduced visabilty. Never full.
Near misses, depends how you define them? I was expected to do what was required.
I have carried out a full crash stop for birds. I can assure you Even with CPP it gets attention.
Point being, I had detected a target ahead, Which turned to words us.
Other times it’s been some, door knob who didn’t want to loose a fish, Why would you go fishing in fog, in a traffic lane in a car toper boat?
The inventor of of hand held GPS fish finders should be hung drawn and quartered. In my Personal opinion.

Ive seen a few faces with shear terror in thier eyes under my bow. at least two commercial fishermen, I am pretty sure they were unaware I was not only stopped but actually going astern when they came out the fog.
Not sure why they kept altering to Port to words me, They Usually have basic heads up radar but were on fly bridge,
I suspect they were missing my fog signal for the nearby lights fog signal.

I cant count, The number of times a small UFO has altered to port into my direction of travel. I don’t know why, I presume they get scared and or confused.
Most are Mobo‘s or fishing often running way to fast in fog,
A few sail boats,

What do I regard as a good CPA?

Hard to say, Depends? Where are we?
Some channels I use are less than 1 cable wide. other times it miles.
What speed am I actually doing?
Hard to say, Depends?

The Stena Line Ferry was highly manoeuvrable, I could stop from full in around 3 cables. Less than 6 cable vis, becomes hard to justify full speed.
With Becker Rudders Turning circle, I was a long time ago, pretty darn tight. I dumped half the duty free store once,
Hotel manager a bit peeved,
I had some splaining to do.
My speed was up, To My judgment at the time, being fully aware, I have to answer for it.

A lecturer many decades ago at GCNS in Masters business, Quote “never do the same speed in restricted visibility you were doing in clear“. “It can’t be justified“ “The same speed in restricted visibility as in clear, The courts have found there was no apparent consideration given To safe speed“.

My personal practice, is not just a synical desire to appear to have considered the state of visibility in determining my speed.

I like to take the top off. 10 to 15 percent, maybe a bit more if if I start to get concerned. It makes a very little difference in speed through the water,
It significantly reduces the time to applying astern propulsion, which reduces my stopping distance.

The report highlighted by Kikuri was interesting.

I cant speak to the practice on container ships. I’ve never set foot on one.

25 knots in restricted visibility, appears remarkably like full sea speed.
These ships usually have Large Slow speed diesel with fixed pitch,
The engines do not like going from full sea speed to manoeuvre ing speed in a hurry.
It can be done,
They dont like going astern at speeds much above 10 knots.
It can be done.

Back in the days of yore, I would have expected, Engines on Stand By at manoeuvring speed.

Finding a 2 cable CPA In restricted visibility.
Quite simply beggars belief. Even in restricted waters on a highly manoeuvre able Ferry.

The unfortunate sailor,
I kind of feel sorry for him. I’m sure the report was a bit embarrassing in the club bar.
Not understanding his radar, How many of the other members of the club do.
Choosing to cross the channel in fog? Was it worth the risk?
Im sure lots of other club members would think it was ok.

He got confused?

Its easy to say from here, Stopping right in front of a container ship is less than wise.

My personal advice, would be,
Keep your course and speed steady,
Be able to stop within about half your visabilty or less.
have your engine ready to manoeuvre
keep a good lookout.
Use hand steering( you don’t want to be fannying about at the last second)

Do some kind of radar course. Or at least RFI.

Make any alteration very large.
Critical avoid a succession of small alterations.

If in doubt stop and take all way off. ( he tried this, perhalps not effectivey) He clearly didn’t know he was stopping right in front of a container ship)

He was extremely unlucky it was this, particular container ship.

better to control your own luck.

If you follow the advice above part I will avoid you.

Even if you do something stupid, for your sake make it bold. I will detect a bold stupid alteration and respond without killing you.

There but for the grace of god go I

To date I haven’.t

I know a couple of people who have.

Probably the closest I have come.
I was OOW, Master had the con.
Not Stena line.
Not quite full speed, see synicle comment
16 ish.
I was ussing old steam radar with hood and plotting Screen. X band
Master using day early generation daylight screen ARPA ( sperry finger touch x band, really good radar actualy)
Thick Low fog Vis 1 or 2 cables,
Near calm
Fog signal, SBE, QM in Wheel, look out posted on bow. all kosher

Speed typical 18 slightly reduced.

I detected a Small Intermittently target perhaps a mile or 2 away approaching fast (guess 20 plus knots) 2 points to Port. Reported to Master.
And suggested reduce speed.
Masters replied, to week and to fast nobody be going that fast in fog. Just happens There was a flight of geese coming in from port.
Master, “Don’t worry its just birds“
Truth, I could see the birds and accepted , His reply ,
I did not press the speed reduction.

Seconds later a small Binlinner Trophy UFO appeared out the fog heading right for us at about 1 cable two points to Port.
doing over 20 knots
All I could do was lean on the whistle the pitch control was to far away.
Niether I nor Master gave a helm order.
The QM went hard to Port.
The boat was going to hit midship
He was an old hand and swung the stern, I think it made a difference
The boat turned away,
Even so I am sure it came close enough to be under the rubbing strake

The old man and I got lucky, we had f’ up. We very nearly killed someone.
Master was very cautious after this.

All any one had to say, Probably Birds. He would slow.

I crash stop for birds

 

[Uricanejack]

I've also seen ground and water stabilised in reference to RADAR, is that the same as Relative/True ? I believe the Wakhuna report uses that terminology (but I've not checked for this thread)

I had a quick thumb through. Didn't notice. I will read better later.

before I start pontificating,
Most of my knowledge is decades old. based on big stuff.
like refuler Iam an old fart more comfortable with a china pencil and relative motion than modern electronics.

I do have a radar on my own boat it’s a basic Furuno 160? At least a decade old. I wouldn’t recognize a MARPA if it bit me, never seen one up close. Or or a multin channel wahetever
I have posted an explanation some time ago. I don’t know how, familiar you are with radar, so I will try and keep this very simple.

My little boat radar is about as simple as they come.

head up. the heading marker I straight up and synced with the boats heading.

Relative Motion. Is all it can do.
The center, is where the scanner is.

It is Unstabalised,
Any yaw of the boats heading will effect the bearing of a target displayed. So targets get spread out as the boats heading changes.
The screen appears to be stationary while the world moves.
Every thing is relative to the boat.

Traditional big ship radars, are gyro compass stabilized.
option head up or North up,

The Advantage targets appear on the same bearing all the time. The ships heading appears to change with the compas heading.

When at anchor
relative motion and true motion are the same
when a target crosses the radar screen its motion is exactly what it appears to be.

As soon as you move, your course speed, become important.

your boat stays in the center, and the world appears to move.
I reality you moved not the world.
What you see, is relative motion.
So any targets are displayed in relative position to the center of the boat scanner and screen.

A target moving at the same course and speed appears to be stationary.

To determine true motion, draw a vector for the course and speed and apply it to the the targets first position, in a manner very similar to a set and drift tide plot.

So far so good. Simple

Ground track or water track.

The problem, what about set and drift?

actually for collision avoidance it doesn’t matter If you use the course and speed through the water course steered and log speed.
Why?
The other vessel or target on your radar is in the same bit of water getting the same set and drift. They can cell out
Set and drift can be ignored.

If you use the course and speed through the water.

Small stationary targets like buoys or beacons. Will appear to move slightly, this movement is the set and drift.

Well so much for old guys with china pencils.

Modern ship radars or ARPA automatic radar plotting aids. Can do all this for us. No need for my pencil.

ARPA should still be stabilized to the ships gyro compass. No problem thete.
So if the ARPA uses the ships gyro course to calculate the vectors for true motion. No Problem.
ARPA is using the course through the water,

what about the speed?
Shpis logs come in a number of variety and types.
The speed required is the speed through the water, a paddle wheel log would work,
Ships Ussualy have fancier logs.
EG a Doppler log. Very accurate.

The problem a Doppler log can calculate the ships speed by measuring the Doppler shift of a sound signal to the bottom.
This is ground speed.

Or a Doppler log can measure the Doppler shift to layer in the water
This will give Speed through the water

Water speed is the speed required.

The true motion used for colision avoidance,
Is not actually true motion
The true motion used for collision avoidance is the true motion through the water.

If ground speed is used the true motion calculated will have an error caused by the effect of the current On the ships speed.

The CPA or closes point of approach, is calculated from the relative motion and should be unaffected.
The true course and speed of a tracked target may have an error.

So for colision avoidance with an arpa radar if it is on relative motion. It’s not a problem

If set on true motion there may be an error.

A ship Transiting the Channel. The current will be tidal and with or against the ship
So it will affect the speed of the ship over the ground.

Many radar operators on many ships today will set thier ARPA to GPS. Why?
Navigation and particular chart over la.y. A ground stabazided radar picture will coincide with the GPS and the chart.

The radar still takes observations and measurements of a target which is moving through the water.
The small stationary targets like buoys or beacons appear to be stationary matching the chart.
All the true motion target calculations for other vessels now have an error Equal to the set and drift.

So fundamentally flawed for collision avoidance.

How big a problem.

Due to drive systems, Doppler logs don't work On some of our vessels.
Some of our smaller vessels don’t have gyro compass.
Traditional ARPA doesn’t work.
Ussing a GPS to stabilize the radar, doesn’t meet ARPA requirements.

One might easily argue it beets the heck out of a pencil.

So on some vessels a GPS ground stabilized radar is the only practical option.

Just be aware there is a potential error.

True course and speeds displayed may not be correct. if you know this it is no longer a problem.

MARPA which is a Mini ARPA probably can only be ground stabilized unless you happen to have a gyro compass and Doppler log.
I don’t know enough about them to give a definitive answer.
or if other types of flux gate, satellite stuff can replicate a gyro and Doppler log.

My opinion a GPS Mini ARPA Multi display whats it. would beet the heck out of a pencil.

Personally I prefer to Stay in the harbour with a cold beer than head out in fog.

if I get caught out I will get by. With my crappy unstable display.

If interested the greatest effect of a speed error on a true motion plot.
Is on the true course in a a crossing Situation.

head on or overtaking True course unaffected True speed, who cares it’s head on.

Did it make a difference to the situation in this report.,If the MAIB said so who am I to argue.

25 knots in fog, two cable CPA, is pretty damn close error or no error

 

[Babylon]

Interesting thread for a yachtie to peruse...

The most useful thing my radar has ever done is convince me to abort a channel crossing four hours out in increasingly thick fog and a rising wind (having only two novices as crew) with a numerous titans on the screen marching out of the east!

 

[RobbieW]

I had a quick thumb through. Didn't notice. I will read better later.

before I start pontificating,
Most of my knowledge is decades old. based on big stuff.
like refuler Iam an old fart more comfortable with a china pencil and relative motion than modern electronics.

I do have a radar on my own boat it’s a basic Furuno 160? At least a decade old. I wouldn’t recognize a MARPA if it bit me, never seen one up close. Or or a multin channel wahetever
I have posted an explanation some time ago. I don’t know how, familiar you are with radar, so I will try and keep this very simple.

My little boat radar is about as simple as they come.

head up. the heading marker I straight up and synced with the boats heading.

Relative Motion. Is all it can do.
The center, is where the scanner is.

It is Unstabalised,
Any yaw of the boats heading will effect the bearing of a target displayed. So targets get spread out as the boats heading changes.
The screen appears to be stationary while the world moves.
Every thing is relative to the boat.

Traditional big ship radars, are gyro compass stabilized.
option head up or North up,

The Advantage targets appear on the same bearing all the time. The ships heading appears to change with the compas heading.

When at anchor
relative motion and true motion are the same
when a target crosses the radar screen its motion is exactly what it appears to be.

As soon as you move, your course speed, become important.

your boat stays in the center, and the world appears to move.
I reality you moved not the world.
What you see, is relative motion.
So any targets are displayed in relative position to the center of the boat scanner and screen.

A target moving at the same course and speed appears to be stationary.

To determine true motion, draw a vector for the course and speed and apply it to the the targets first position, in a manner very similar to a set and drift tide plot.

So far so good. Simple

Ground track or water track.

The problem, what about set and drift?

actually for collision avoidance it doesn’t matter If you use the course and speed through the water course steered and log speed.
Why?
The other vessel or target on your radar is in the same bit of water getting the same set and drift. They can cell out
Set and drift can be ignored.

If you use the course and speed through the water.

Small stationary targets like buoys or beacons. Will appear to move slightly, this movement is the set and drift.

Well so much for old guys with china pencils.

Modern ship radars or ARPA automatic radar plotting aids. Can do all this for us. No need for my pencil.

ARPA should still be stabilized to the ships gyro compass. No problem thete.
So if the ARPA uses the ships gyro course to calculate the vectors for true motion. No Problem.
ARPA is using the course through the water,

what about the speed?
Shpis logs come in a number of variety and types.
The speed required is the speed through the water, a paddle wheel log would work,
Ships Ussualy have fancier logs.
EG a Doppler log. Very accurate.

The problem a Doppler log can calculate the ships speed by measuring the Doppler shift of a sound signal to the bottom.
This is ground speed.

Or a Doppler log can measure the Doppler shift to layer in the water
This will give Speed through the water

Water speed is the speed required.

The true motion used for colision avoidance,
Is not actually true motion
The true motion used for collision avoidance is the true motion through the water.

If ground speed is used the true motion calculated will have an error caused by the effect of the current On the ships speed.

The CPA or closes point of approach, is calculated from the relative motion and should be unaffected.
The true course and speed of a tracked target may have an error.

So for colision avoidance with an arpa radar if it is on relative motion. It’s not a problem

If set on true motion there may be an error.

A ship Transiting the Channel. The current will be tidal and with or against the ship
So it will affect the speed of the ship over the ground.

Many radar operators on many ships today will set thier ARPA to GPS. Why?
Navigation and particular chart over la.y. A ground stabazided radar picture will coincide with the GPS and the chart.

The radar still takes observations and measurements of a target which is moving through the water.
The small stationary targets like buoys or beacons appear to be stationary matching the chart.
All the true motion target calculations for other vessels now have an error Equal to the set and drift.

So fundamentally flawed for collision avoidance.

How big a problem.

Due to drive systems, Doppler logs don't work On some of our vessels.
Some of our smaller vessels don’t have gyro compass.
Traditional ARPA doesn’t work.
Ussing a GPS to stabilize the radar, doesn’t meet ARPA requirements.

One might easily argue it beets the heck out of a pencil.

So on some vessels a GPS ground stabilized radar is the only practical option.

Just be aware there is a potential error.

True course and speeds displayed may not be correct. if you know this it is no longer a problem.

MARPA which is a Mini ARPA probably can only be ground stabilized unless you happen to have a gyro compass and Doppler log.
I don’t know enough about them to give a definitive answer.
or if other types of flux gate, satellite stuff can replicate a gyro and Doppler log.

My opinion a GPS Mini ARPA Multi display whats it. would beet the heck out of a pencil.

Personally I prefer to Stay in the harbour with a cold beer than head out in fog.

if I get caught out I will get by. With my crappy unstable display.

If interested the greatest effect of a speed error on a true motion plot.
Is on the true course in a a crossing Situation.

head on or overtaking True course unaffected True speed, who cares it’s head on.

Did it make a difference to the situation in this report.,If the MAIB said so who am I to argue.

25 knots in fog, two cable CPA, is pretty damn close error or no error

Thanks for taking the time to type all that. It's improved my understanding of the variables in radar work, in particular stabilisation

 

[capnsensible]

Thanks from me too Uricanejack. A great read.

 

[lw395]

I've not been involved with civilian marine radar, but on many naval systems of old, there were several expensive parts with relatively short lives, such as T/R cells which protect the receiver from the transmit power. Could be navy trained people inflicting their culture on the civilians...

 

[Refueler]

I was StenaBulk for a few years ..... part of Concordia Maritime.

I joined them when they took their first two tankers of the Banks from Layup ... paid peanuts for them ... Stena Pacifica (~100,000 tonne) and Stena Atlantica (250,000 tonne) ... both ended up in Iraq - Iran War as shuttles ...
Pacifica was 'my ship' and I was still with her when we handed her over to a new Greek owner in Setubal ...

 

[Dan Tribe]

I loved this sketch from Only Fools and Horses.
Uncle Albert (Holding a photo of him in the war): I’m talking about HMS Peerless.
Del: Oh sorry.
Uncle Albert: Just a few hours after that photo was taken we was in action.
Rodney (Studying photo): I’m surprised it took you that long!
Uncle Albert: A Japanese sub was spotted in the area.
Del: That’s all you need, innit?
Uncle Albert: There was an American aircraft-carrier, anchored off-shore. The USS Pittsburgh. It was our job to protect her. Well, we’d only been sailing for about an hour and we crashed right into her. Cor, didn’t half make a noise!
Del (Incredulous): You went and whacked into the boat that you were going out to protect?
Uncle Albert: Yeah. It was a good job she was there actually, she picked up most of the survivors.
Rodney: Was your ship badly damaged?
Uncle Albert: We couldn’t tell, Rodney, it sunk. Course, they tried to put the blame on me.
Del: Sounds fair.
Uncle Albert: Just ‘cos I was on watch at the time. I had me excuses ready.
Rodney: What, you were drunk?
Uncle Albert: Don’t be silly! The American vessel was at battle stations and was showing no light. You weren’t allowed, there was a war on.
Del: Course there was.
Uncle Albert: So then they tried to get me on naval technicalities, like it happened in broad daylight.
Rodney: You didn’t see an aircraft carrier?
Del: Forty-two thousand tons of steel!
Rodney: In broad daylight!
Uncle Albert: Well, I wasn’t close enough!
Rodney: You must have been reasonably close, Unc, you hit it!
Del: They’d have stood more chance with Ray Charles in the crow’s nest!
Uncle Albert: Well, I mean I wasn’t up on deck. I was in the radar room watching the screen. I couldn’t make head nor tail of it. It was all blibs and blobs. Still, the Japanese sub had it away a bit lively.