A
Anonymous
Guest
Re: colregs - ugh ....... hang on a mo ....
You're missing the point. Forget it, life's too short.
You're missing the point. Forget it, life's too short.
G
Guest
Guest
How missed the point ?
I read through and find some posts advocating adding rules to make smaller vessels give way to larger .... and later you mention extra lights / signals for this .... with a comment - technology etc. is already there ...
But in fact the rules and signals are already there ..... and why add to an already complicated mess ??
I read through and find some posts advocating adding rules to make smaller vessels give way to larger .... and later you mention extra lights / signals for this .... with a comment - technology etc. is already there ...
But in fact the rules and signals are already there ..... and why add to an already complicated mess ??
Mirelle
N/A
Something that I have a fad about
You don't mention a Doppler log but I assume that she has one - she may not as these are fairly pricey bits of kit - US$ 70K or so, so superintendents chop them off the spec.
If fitted they are a great help in berthing and anchoring - provided that (and this is often overlooked) the readout is adjacent to a GPS readout. You need to know what you are doing through the water and over the ground at the same time.
You don't mention a Doppler log but I assume that she has one - she may not as these are fairly pricey bits of kit - US$ 70K or so, so superintendents chop them off the spec.
If fitted they are a great help in berthing and anchoring - provided that (and this is often overlooked) the readout is adjacent to a GPS readout. You need to know what you are doing through the water and over the ground at the same time.
G
Guest
Guest
Re: Is this relevant??
RobertW you missed a bit.
"The situation is a large ship ASTERN of you"
If you carry straight on he would hit you.
The only option if yachts have to give way to ships would be a turn to port (right angles to the ship and try to make the 1/4 mile) How long would it take to get the steering gear off and let out the sails or would you start the engine. What ever it would be a mad panic.
What if the ship had oversteered in your initial estimation of its direction!!
It is impossible for ships to have right of way at all times. The colregs are the only way. The ships just need a way to know of your position and communicate their intentions in good time. If you stop to let them past they need to know they are the stand on vessel and you exist. If they are overtaking they need to know that there is a stand on vessel ahead that will continue its course.
It takes nothing for a simple call on the radio and they have your call sign if anything crops up as you get closer. As I said in open ocean where the closest approach is less than a mile.
RobertW you missed a bit.
"The situation is a large ship ASTERN of you"
If you carry straight on he would hit you.
The only option if yachts have to give way to ships would be a turn to port (right angles to the ship and try to make the 1/4 mile) How long would it take to get the steering gear off and let out the sails or would you start the engine. What ever it would be a mad panic.
What if the ship had oversteered in your initial estimation of its direction!!
It is impossible for ships to have right of way at all times. The colregs are the only way. The ships just need a way to know of your position and communicate their intentions in good time. If you stop to let them past they need to know they are the stand on vessel and you exist. If they are overtaking they need to know that there is a stand on vessel ahead that will continue its course.
It takes nothing for a simple call on the radio and they have your call sign if anything crops up as you get closer. As I said in open ocean where the closest approach is less than a mile.
G
Guest
Guest
Re: Something that I have a fad about
No Doppler ..... but one of the latest EM logs ....
I can remember being on ships with Doppler logs when they first came out !! And also when they started fitting Doppler berthing gear .... cr*p !! Putting it simply - they were so unreliable ..... forever breaking down and in the end most ships I was on - they were switched off and ignored. EM and Pitot logs were accepted and IMHO - along with most other officers I knew - respected much more .... particularly that they gave actual speed through water and not all this stuff about layered water and all that ........... I think you know what I mean !! I can see the point of a Doppler log if you are coastal / in out of harbour all the time ..... but deep-sea ship ?
No Doppler ..... but one of the latest EM logs ....
I can remember being on ships with Doppler logs when they first came out !! And also when they started fitting Doppler berthing gear .... cr*p !! Putting it simply - they were so unreliable ..... forever breaking down and in the end most ships I was on - they were switched off and ignored. EM and Pitot logs were accepted and IMHO - along with most other officers I knew - respected much more .... particularly that they gave actual speed through water and not all this stuff about layered water and all that ........... I think you know what I mean !! I can see the point of a Doppler log if you are coastal / in out of harbour all the time ..... but deep-sea ship ?
tome
Well-Known Member
Re: Something that I have a fad about
Our ships are fitted with retractable acoustic transducers on a long pole which goes out through a sea chest. It's designed for use at normal survey speeds (5/6 kts). Forget to retract it before ordering passage speeds and you add 3 metres draft plus a bent pole which you'll never retract...
Only did it the once!
Our ships are fitted with retractable acoustic transducers on a long pole which goes out through a sea chest. It's designed for use at normal survey speeds (5/6 kts). Forget to retract it before ordering passage speeds and you add 3 metres draft plus a bent pole which you'll never retract...
Only did it the once!
G
Guest
Guest
Logs ...
When I came of teh Seismic stuff we were still using Pitot Tube logs ... but for shoot the Syledis Nav was used to provide all data on the screens ... even the speed ...
I used to "dream" ...... 1 port, 1 starboard ... up a notch ... down a notch ..... it's something that you tend not to forget hours of that !! Spent a lot of time with the CGG nav's and started looking after it myself based on wheelhouse display ... leaving them to get on with the shoot and Starjet ..... actually started to enjoy it then .... especially when we did the Norwegian Fjords Sub-hunting !! Officially was Gun and cable testing .... but not supposed to talk about that !!
When I came of teh Seismic stuff we were still using Pitot Tube logs ... but for shoot the Syledis Nav was used to provide all data on the screens ... even the speed ...
I used to "dream" ...... 1 port, 1 starboard ... up a notch ... down a notch ..... it's something that you tend not to forget hours of that !! Spent a lot of time with the CGG nav's and started looking after it myself based on wheelhouse display ... leaving them to get on with the shoot and Starjet ..... actually started to enjoy it then .... especially when we did the Norwegian Fjords Sub-hunting !! Officially was Gun and cable testing .... but not supposed to talk about that !!
tome
Well-Known Member
Re: Logs ...
We're not meant to talk about the Norwegian fjord stuff either, even though we made the hydrophone cables they laid across the entrances...
Syledis was great until GPS came along - remember Hyperfix and Pulse 8?
We're not meant to talk about the Norwegian fjord stuff either, even though we made the hydrophone cables they laid across the entrances...
Syledis was great until GPS came along - remember Hyperfix and Pulse 8?
Andrew_Fanner
Well-Known Member
Re: Logs ...
sbc.
Looking back at the thread there was some mention of the time taken from the command for a crash stop until the engines were in reverse (nothing about the ship stopping or going backwards). Bridge controls and no chain of command so I assume that the limiting factor is the sheer inertia of the engines and drivetrain including screw(s). Is there a braking system for the engine at all? I'd assume not unless some marine legislation requires same to expedite an emergency stop or reversal. Likewise is there a level of automation on a modern ship whereby the OOW presses a metaphorical "I want to stop as soon as possible" button and the management system does the rest.
It intrigues me as a comparison to the endless debates that Titanic buffs (mildly guilty there) have about how long the ship would have taken from Full Ahead to Full Astern.
sbc.
Looking back at the thread there was some mention of the time taken from the command for a crash stop until the engines were in reverse (nothing about the ship stopping or going backwards). Bridge controls and no chain of command so I assume that the limiting factor is the sheer inertia of the engines and drivetrain including screw(s). Is there a braking system for the engine at all? I'd assume not unless some marine legislation requires same to expedite an emergency stop or reversal. Likewise is there a level of automation on a modern ship whereby the OOW presses a metaphorical "I want to stop as soon as possible" button and the management system does the rest.
It intrigues me as a comparison to the endless debates that Titanic buffs (mildly guilty there) have about how long the ship would have taken from Full Ahead to Full Astern.
landaftaf
Well-Known Member
Re: Logs ...
they do a 'crash stop' test on initial sea trials, so evey ship has the data.
the results vary considerably - as do ships, and can be several miles for very large ships to maybe a ship length or two for very powerful specilist vessels like anchor handlers ot platform support vessels.
incidentally tests have proven its more effective on large vessels to initially reduce the pitch or rpm than to stop or thrash the prop astern. /forums/images/graemlins/cool.gif
they do a 'crash stop' test on initial sea trials, so evey ship has the data.
the results vary considerably - as do ships, and can be several miles for very large ships to maybe a ship length or two for very powerful specilist vessels like anchor handlers ot platform support vessels.
incidentally tests have proven its more effective on large vessels to initially reduce the pitch or rpm than to stop or thrash the prop astern. /forums/images/graemlins/cool.gif
RupertW
Well-Known Member
Re: Is this relevant??
Agreed if the ship is dead astern and on the same heading as the yacht -then a turn would be needed to avoid collision - which wasn't quite what I'd pictured - sorry.
If the ship was in any other angle astern of the yacht and pointing at the yacht's current position whilst still 3 minutes away then they'd be on diverging courses and could both remain on their present headings. If they were on a collision course, i.e the ship was coming up obliquely from astern so their paths would cross, then that's when my hard turn to port would slow down the yacht (from reach to run) and allow the yacht to let the ship go past and go round it's stern. Crucially it would also make the yacht's intentions immediately clear.
In general terms, though, you cannot assume that a collision course just 3 minutes away will be dealt with by a ship obeying colregs. It frequently will not happen for good or bad reasons, whether in busy shipping routes or in the open ocean. If a ship is not reacting properly, then surely you just have to get out of its way clearly and quickly.
If you really cannot alter your course rapidly, then I think there's something to be said for changing the gear you use and/or disengaging it as soon as you see any ships at all.
Agreed if the ship is dead astern and on the same heading as the yacht -then a turn would be needed to avoid collision - which wasn't quite what I'd pictured - sorry.
If the ship was in any other angle astern of the yacht and pointing at the yacht's current position whilst still 3 minutes away then they'd be on diverging courses and could both remain on their present headings. If they were on a collision course, i.e the ship was coming up obliquely from astern so their paths would cross, then that's when my hard turn to port would slow down the yacht (from reach to run) and allow the yacht to let the ship go past and go round it's stern. Crucially it would also make the yacht's intentions immediately clear.
In general terms, though, you cannot assume that a collision course just 3 minutes away will be dealt with by a ship obeying colregs. It frequently will not happen for good or bad reasons, whether in busy shipping routes or in the open ocean. If a ship is not reacting properly, then surely you just have to get out of its way clearly and quickly.
If you really cannot alter your course rapidly, then I think there's something to be said for changing the gear you use and/or disengaging it as soon as you see any ships at all.
G
Guest
Guest
Re: Logs ... Syledis ...
Some stories about that ... Paying Local Mafia guy in Sicily so that we could mount one transponder in his garden !! Had to buy the cart and donkey to carry it there as well.....
North Sea ... Rig skids - when the b******ds didn't tell you and then bl**y nav went wonky ....
As you know I was with Syledis and Loran ... UGH !! Loran .... why did I have to mention that cr*p !!! GPS was still only in its infancy then ... showing my age now !!
Some stories about that ... Paying Local Mafia guy in Sicily so that we could mount one transponder in his garden !! Had to buy the cart and donkey to carry it there as well.....
North Sea ... Rig skids - when the b******ds didn't tell you and then bl**y nav went wonky ....
As you know I was with Syledis and Loran ... UGH !! Loran .... why did I have to mention that cr*p !!! GPS was still only in its infancy then ... showing my age now !!
G
Guest
Guest
Systems vary on ships for Emerg. Stops
If on Bridge Control - often there is an over-ride that gives a controlled set of orders to the engines. Remember a motor ship - the engines actually run backwards to go astern .. So have to physically stop to change. There isn't in effect a clutch - so its direct via gearbox.
In steam ship days - I can say that later steamers I was on ... 300,000 ton jobs ... at full away speed at sea .. you would hit the "Red Button" ... immediately the turbine would be "braked" by frequent blasts of steam to slow it down ... once shaft falls to low level - slow astern steam is applied and increases as shaft starts to rotate astern.
Motor ships of course can't do this due to the engine design - but have a variation that effectively produces a controlled change maximising effect with least cavitation.
Yes it is possible to over-ride if you are daft enough ! But all you will do is create damage and cavitation.
A CPP system - Controllable Pitch Propellor system would have an interlink as well to prevent overstressing system by too violent an astern command.
To try and compare - its like ABS on your car ... controlled stop is better than an uncontrolled stop ... in most cases quicker and shorter distance.
As to time to stop ... memory .... I can recall figures of 7 mins, 17 mins etc. - all depends on vessel.
If on Bridge Control - often there is an over-ride that gives a controlled set of orders to the engines. Remember a motor ship - the engines actually run backwards to go astern .. So have to physically stop to change. There isn't in effect a clutch - so its direct via gearbox.
In steam ship days - I can say that later steamers I was on ... 300,000 ton jobs ... at full away speed at sea .. you would hit the "Red Button" ... immediately the turbine would be "braked" by frequent blasts of steam to slow it down ... once shaft falls to low level - slow astern steam is applied and increases as shaft starts to rotate astern.
Motor ships of course can't do this due to the engine design - but have a variation that effectively produces a controlled change maximising effect with least cavitation.
Yes it is possible to over-ride if you are daft enough ! But all you will do is create damage and cavitation.
A CPP system - Controllable Pitch Propellor system would have an interlink as well to prevent overstressing system by too violent an astern command.
To try and compare - its like ABS on your car ... controlled stop is better than an uncontrolled stop ... in most cases quicker and shorter distance.
As to time to stop ... memory .... I can recall figures of 7 mins, 17 mins etc. - all depends on vessel.
