# Stopping Distances



## Twocky61

Obviously no ship is able to execute an emergency stop on a sixpence (a small silver coin of uk currency long out of circulation.)

So what is the actual stopping distance on full reverse engine thrust on: 

1) a tanker ship full of crude oil? 

2) a fully laden container ship (of cars for example)?

Thanks all you marine type guys (& gals) in the know 

Nick


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## DURANGO

from what i remember was it not 25 miles for a tanker to stop dead in the water from finished with engines oooooops I jumped in without reading the question properly from full ahead to full astern i better leave that to someone who knows what they are talking about which certainly is not me regards


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## Duncan112

Just to add fuel to the bonfire in the late 80's a paper was published suggesting that an immediate "Full Astern" from full sea speed was not the most efficient or shortest method of stopping a ship. The preferred method was to reduce engine speed until it was slightly below ships speed, as the ship's speed falls further reduce ahead revs until below ships speed. The theory was the braking effect of this was greater than that given by the propeller rotating astern with headway on the vessel.


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## frangio

Sure I was told on Ardvar that a Full Ahead to Full Astern would put too much strain on the shaft and could cause it to part.

Don't think we took anything like 25 miles to stop. Do remember there were articles in non-nautical publications where so called experts claimed that if one of the big tankers ran aground they would travel a mile or more inland! Seems they'd forgotten a lot about the physics they'd done at school!


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## Laurie Ridyard

Two points....

1. Probably the quickest way to stop a ship is stop the engines, then go hard aport, hard astarboard, hard aport etc. then go hard astern.
2. The rule of the road is to keep your speed so that you can stop in half the visibility.

I heard a story about a Hain Skipper " Rotten Ronnie" Richards, who was a right piss artist, going into Dakar. The first trip 3/0 poor lad, kept calling him as they approached the Pilot Boat. He came up at the last minute and ordered " Stop Engines" . The 2nd Engineer could not, as he had not fired up the port boiler, so the ship went sailing merrily past the Pilot Boat into and around the harbour; then back out again ! I understand he got fined for it.

Laurie Ridyard.


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## Twocky61

Thanks for all your input guys 

Another aspect of course is all those rich, Sunday, gin swilling, Sunseeker owners, who like to cross across the front of ferries/container/tanker ships playing Russian Roulette and then wonder why their boat was hit by the bigger ship 

In fact, are private non commercial boats allowed in shipping lanes?


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## DURANGO

frangio said:


> Sure I was told on Ardvar that a Full Ahead to Full Astern would put too much strain on the shaft and could cause it to part.
> 
> Don't think we took anything like 25 miles to stop. Do remember there were articles in non-nautical publications where so called experts claimed that if one of the big tankers ran aground they would travel a mile or more inland! Seems they'd forgotten a lot about the physics they'd done at school!


 I,m afraid I jumped in with me boots on without properly reading the original question what I ment by a stopping distance of 25 miles was if a fully loaded tanker was steaming full ahead and then the engines where stopped without going astern that it would take up to 25 miles for her to stop dead in the water you have to remember this is from someone[ myself ]who is usually wrong about most things regards


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## Laurie Ridyard

As far as I recall, small craft are required to keep out of the way of large vessels in shipping lanes and waterways for obvious reasons.


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## ChasH

*chasH*

I was on the Esso Austria if i remember right she was 100,000 tonner and we were fully loaded, the captain decided to swop library books with the Esso Dublin she i think was a 36er obviously the two captains spoke to each other, but if i remember right from full ahead 16 knots, to stop engines, no other movements, it work out roughly a knot a mile and we weren't far off abeam of each other when we stopped, i have no idea what the other ship did, bearing in mind we are talking about 60,000 tons different.
chas


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## Cutsplice

There are many variables to consider, size of vessel, loaded, light ship, original speed, weather conditions, currents, trim etc. Then whether you want to stop and maintain the vessels original heading, it's difficult to give a definitive answer, I am awaiting some real gems of answers to surface as a result of this question.


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## Stephen J. Card

Stop engine... or at least as least down the minimum revs. But keep the rudder hard over..... port to starboard and keep again.... large rudder will slow you down.


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## skipni

As Master of an Aframax tanker (105,000t DWT) we can stop a ship in 1/2 nautical mile. My C/E had problem down below and needed to shut down quick I did a Willimianson turn and was able do it it within 4 cables. Lost 70% of the speed in the turn and then going full astern the vessel was stopped and ready to anchor. I this stage I was still waiting for the anchor party to go forward as everything happened so fast.


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## woodend

My last fully laden VLCC piloting job into Saldanha was in 1986. However I always liked to board between 10 and 12 nautical miles off the Heads, which gave me plenty of time to work off the boarding speed to get her at 2.5 knots as we came through the Heads. Then we still had almost 5 miles to run to the Turning Basin off the end of the Tanker Berth. The four tugs would meet us just out of the swells so they were fast and had their wires stretched by the time we were ready to do a 180* standing turn between the buoys. I can assure you the 4 - 5 hours the job took were tiring.[=P]


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## TOM ALEXANDER

Cutsplice said:


> There are many variables to consider, size of vessel, loaded, light ship, original speed, weather conditions, currents, trim etc. Then whether you want to stop and maintain the vessels original heading, it's difficult to give a definitive answer, I am awaiting some real gems of answers to surface as a result of this question.


One thing not noted so far as I can gather is the type of engine/propulsion. I'm not an engineer, but there was always a reluctance on the part of the engineers to go from full away to full astern on the steam turbine/double reduction gear set up. Didn't seem to be such an important issue on a direct drive Doxford. The reason that full astern would not work so well was the cavitaion caused by a standard propeller dragging air down from the surface and causing a paddle wheel effect on the stern of the vessel in addition to reducing the drag on the prop - not too good in a narrow channel. Never sailed on diesel electric/azipods, or even with Kort nozzles, so cannot comment on those. The stopping distance would also depend on whether the vessle had one screw, two or more, and the diameter/pitch. Co-efficient of fineness of the hull coupled with inertia would also have a bearing. My best guess for an _average_??? Figure on a mile -- but leaving 2 - 3 miles at least would be erring on the side of safety.


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## howardws

MV Lion, P&O Ferries in about 1980. Someone ashore decided they needed to know our stopping distance and turning circle, both from full speed - about 21 knots. She stopped in twice her own length and the turning circle was also twice her length. Incidentally a first stop was made by bringing her from full ahead to full astern quite slowly (KaMeWa VPP)and took more than twice her length, a second, at my suggestion, was full ahead to full astern as fast as possible.


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## Phil Saul

I was in the Westmorland in 1970 coasting prior to going deep-sea and we were approaching Swansea.
No idea what speed we were doing, but we weren't flat out, when some guy in a sailboat decided to cut across ahead of us but capsized in our path.
I was working in the saloon when the deck started heaving and all the cutlery started bouncing off the tables as the ship made an emergency stop.
We managed to avoid steaming over the guy but he was very lucky.

Question.

Is it panic-stations down below, given that you have no idea what's going on and emergency stops aren't all that common an event, or is it all cool calm and collected and just another drill.

Always wondered about that for all these years but never thought to ask.

Regards Phil (Thumb)


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## NoR

Big steamships, VLCCs and the like, needed about two days notice in writing to get an astern movement.


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## Jose Manuel Ortega

VLCC tanker, full ahead manoeuvering speed 13 knots, wide entrance channel, then half ahead, hard stbd, when 20 degrees rate of turn hard port and when the wheel in hard a port position slow ahead, then when rate of turn in 20 degrees to port, hard stbd and when initiated the swing to stbd, then dead slow ahead. Once more same procedure to port and speed should be for this time 5 to 6 knots. When the swing is hard a port we can start engine to stern gradually until full. Over 6 knots you can be very friend of the Cheng but he will kill you. Distance to full stop between 2.5 and 3 miles


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## Ron Stringer

woodend said:


> .. I always liked to board between 10 and 12 nautical miles off the Heads, which gave me plenty of time to work off the boarding speed to get her at 2.5 knots as we came through the Heads. [=P]


When I was on the "_Regent Pembroke_" (63000 dwt, steam turbine, single propellor) the Mates reckoned that below 3 knots she was unsteerable. That made for some hairy dockings and a few tightly-clenched buttocks when passing light-ship through the Suez Canal. On our first visit to Pointe à Pierre we took out one of the dolphins.

Various reasons were put forwards for her poor handling at slow speeds - experimental skegless rudder, rugger too small, prop not big enough, form too full at the stern - you name it.

Whatever the reason, as Sparks I could always be certain of entertainment after having sent QTP and before we eventually tied up.


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## ART6

frangio said:


> Sure I was told on Ardvar that a Full Ahead to Full Astern would put too much strain on the shaft and could cause it to part.


I've never heard of that one. In my time with Esso double rings astern were not all that unusual - I once did five in succession when senior second on the Esso York, going up a river in Venezuela.



Phil Saul said:


> Question.
> Is it panic-stations down below, given that you have no idea what's going on and emergency stops aren't all that common an event, or is it all cool calm and collected and just another drill.
> 
> Always wondered about that for all these years but never thought to ask.
> 
> Regards Phil (Thumb)


Working from the assumption that the guys on the bridge didn't go in for such adventures unless absolutely necessary, everything in the engine room of a steam ship had to be calm and collected, because there were many things to do at once. The trick was to spin the ahead throttle shut while spinning the astern one open without lifting the boiler safety valves or losing their water levels up or down. That meant that the second engineer on the throttles would be watching gauges like a hawk while listening to the noises of the turbines so as to avoid wrecking them. In the boiler room the third engineer would concentrate on playing tunes with the oil burners, predicting what would happen next and trying to second-guess. No time for panic!


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## Michael Taylor

After leaving the Sea I left the UK to live in the States (wife) where I finally ended up working in New Bedford MA in the cold storage business. Reaching our terminal required freezer vessel navigate a swing bridge opening and a complicated manover swinging around another facility into the terminal berth. On this occasion the vessels engine for some reason did not respond and the vessel was heading directly into a barge alongside an ajacent fish production plant. The pilot rang a double full astern which stopped the vessel (sank the barge how ever) and saved the day.......except that the violent wash caused some 20 bales of marijuna that some fishing boats had placed under water on timers. Maybe some of the Reefer Vessel officers can remember...the vessel name will come back to me later.


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## OilJiver

Michael Taylor said:


> After leaving the Sea I left the UK to live in the States (wife) where I finally ended up working in New Bedford MA in the cold storage business. Reaching our terminal required freezer vessel navigate a swing bridge opening and a complicated manover swinging around another facility into the terminal berth. On this occasion the vessels engine for some reason did not respond and the vessel was heading directly into a barge alongside an ajacent fish production plant. The pilot rang a double full astern which stopped the vessel (sank the barge how ever) and saved the day.......except that the violent wash caused some 20 bales of marijuna that some fishing boats had placed under water on timers. Maybe some of the Reefer Vessel officers can remember...the vessel name will come back to me later.


Never had much trouble with Doxfords myself, but (memorably) had difficulty getting an astern out of one once. Not good any time, particularly when on standby for entering harbour. 
Anyway (as learned later) seems the ship was approaching the breakwater far too fast. Think we were on the second double ring before I could coax the engine into going astern. Used all the air (steam recip compressors running their guts out) and lifted most, if not all, of the relief valves.
Thankfully no collisions, groundings or other mishap resulted. Had to buy the boys a beer though, on account of the rel v/vs. (Not those upstairs mind!)


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## dannic

Twin screw motor VLCC heap of junk built in Yugoslavia, had crash-stop button on bridge. Theory was it shut fuel off both engines, applied very large disc brakes mounted on propshafts until stopped and then started both engines astern. Simultaneously both rudders would go 15 degrees outboard and both anchors would start to pay-out! Service speed supposed to be 18 knots (thats what they said!). 
Thinking onboard was both props would fall off, rudders would never be seen again and as for the foc's'le....needless to say was disconnected and never tried but shows how dangerous naval architects can be!
Dannic


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## harry t.

*Stopping distance of a bulk carrier*

On a gearless bulk carrier displacing about 140,000 tonnes when fully loaded, so as not to put undue stress on the engines, it is advisable to start slowing down about 50 miles from port.(261 metres long x 40 metres wide x 16.75 metres loaded draft.) Sulzer-single screw. Max. speed - 16 knots
In a ballast condition, that is , no cargo but with 60,000 tonnes of sea -water ballast in the tanks, the ship will travel 11.5 miles after the engine is stopped. If an “emergency stop” is given, i.e. to stop the engine, and then go to full astern, the ship will take 3.8 miles to stop making way thru’ the water, but note, the only time this is done deliberately, is when a new build is on trials before leaving the builders yard and before the owner takes delivery, as this manoeuvre could wreck the engine. At full speed, in the same ballast condition, turning to port or starboard, the minimum turning circle is .75 miles.


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## luigi

If I remember correctly the Globtiks London and Tokyo (485,000 TDW) would (emergency) stop in 17 minutes and 2.7 miles, or thereabouts.

Turning circles were around 6 cables, slightly tighter to port (due to clockwise screw), so turning out of trouble was far preferable to trying to stop.


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