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acelanceloet
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 5th, 2017, 7:45 pm
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Tobius wrote: *
"They're used [when docking] because you need a clear view of the ships side when doing that [almost anything]..."

Docking and/or collision avoidance, for example. Just sayin...
No, if you can only see an object you are going to collide with from the bridge wing, something else has gone wrong. also, colission avoidance is something else entirely from what you described in your earlier post.

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Thiel
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 5th, 2017, 7:47 pm
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Tobius wrote: *
"They're used [when docking] because you need a clear view of the ships side when doing that [almost anything]..."

Docking and/or collision avoidance, for example. Just sayin...
These two things have nothing in common. Heck, they're taught as separate classes, at different semesters as far removed from each other as they can be

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Tobius
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 5th, 2017, 7:50 pm
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acelanceloet wrote: *
Tobius wrote: *
"They're used [when docking] because you need a clear view of the ships side when doing that [almost anything]..."

Docking and/or collision avoidance, for example. Just sayin...
No, if you can only see an object you are going to collide with from the bridge wing, something else has gone wrong. also, colission avoidance is something else entirely from what you described in your earlier post.
It was set for Thiel to discover through such a response, exactly why I argued perspective matters in steerage, but you instead made my point for me. Thank you for the help. I appreciate it.
Thiel wrote: *
Tobius wrote: *
"They're used [when docking] because you need a clear view of the ships side when doing that [almost anything]..."

Docking and/or collision avoidance, for example. Just sayin...
These two things have nothing in common. Heck, they're taught as separate classes, at different semesters as far removed from each other as they can be
Actually maneuvering an object in tight constraints and limited time? Deconfliction is how I address it from my PoV, but I believe nautically you are correct.


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Thiel
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 5th, 2017, 8:05 pm
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By the time you're close enough that the bridge wings become relevant for collision avoidance you're too close to do any collision avoidance on the vast majority of ships. The gear simply doesn't react fast enough. Heck, if you're that close suction and bow wave effects will have more power than anything you have available.

But anyway, I don't disagree that the classic stern position is better, but from practical experience as well as the opinions of my colleagues and instructors it's nowhere near as debilitating an effect as you think.

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acelanceloet
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 5th, 2017, 8:19 pm
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Tobius, Your point of view might be wrong then.

I only have expertise from a shipbuilding perspective, but docking and collission avoidance are done in different waters, at different speeds, with different objectives and with different control systems. because of that, they are also (partially) done from different places on the ship:

collision avoidance is done from your main control point, the pilothouse, where you have all information possible available to you: radars, watchkeepers, camera's and your ships actual behaviour information.

Docking is done (partially) from the bridge wing, as you only need information about 2 things in the final stage: the position of your ship relative to the quay and the movement of your ship (in waves, wind etc) which can only be accurately judged when you have eyes seeing those.

If you have the possibility of colliding with something that is so close that you can only see it from the bridge wing, it might be already too close to do anything about it, depending on the speed and conditions. But thanks for making the point that when avoiding collision, it might be a good idea to have a good viewpoint towards where your ship is going: you are actually telling us about a great advantage of the forward conning position!

We have to keep in mind that many warships have a conning position quite far forward, as have many heavy lift ships and quite a few others. I go with Thiel's expertise here, the classic position offers advantages, but so does the forward one. In most cases the aft position is better, but there is no case whatsoever you can make for the bow conning position as terrible as you make it be. See this post earlier in this thread.

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heuhen
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 5th, 2017, 10:51 pm
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we use forward position on many ships we operate in Norway, due to they are operating in narrow fjords, even supply ships have forward position due to they have to operate close to offshore rigs, there have come some aft position offshore supply ships, due to modern sensors and computers are controlling the ship and holding it in position with help of sensors


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Wikipedia & Universe
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 5th, 2017, 11:53 pm
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Thiel wrote: *
I don't think a split layout is going to make sense on a ship of that size without the need for forward tankage. You're losing an entire cargo hold that way.
By split layout, I assume you mean the superstructure and space beneath it being located amidships? What would be a better option? Locating the bridge aft below a certain TEU threshold (say 10,000 TEU) and forward-amidships (like the Triple-E class) above that threshold? I say 10,000 TEU because that's where it looks like the bridge starts to come forward in this infographic:
[ img ]
Quote:
I'm not sure how well hull shapes scales, you'll have to talk with Ace about that.
Combined RORO and container carriers are a thing and there's been more than a few conversions so that should be entirely doable. Whether it makes economical sense is an entirely different question I can't answer.
I'll send Ace a PM to highlight this question.
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Using the same hull for a bulk carrier however, doesn't make sense. You can't carry bulk cargoes on deck for obvious reasons, so having a hull optimised for deck cargoes doesn't make sense. Plus there's usually no real time pressure. It doesn't matter if that load of scrap or grain arrives in a week or three weeks as long as it's on time.
I'm starting to see that looking at some images of bulkers, especially this infographic comparing the MV Mærsk Mc-Kinney Møller to the MS Vale Brasil. The waterline alone indicates that this is a very different type of hull, apparently optimized to lower the center of gravity for the bulk loads, which can't be accomplished simply by putting huge tanks where the container holds would go.
[ img ]
acelanceloet wrote: *
We have to keep in mind that many warships have a conning position quite far forward, as have many heavy lift ships and quite a few others. I go with Thiel's expertise here, the classic position offers advantages, but so does the forward one. In most cases the aft position is better, but there is no case whatsoever you can make for the bow conning position as terrible as you make it be.
What would you personally recommend for the line of ships I have in mind?

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Thiel
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 6th, 2017, 3:33 am
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Clear sight lines. According to IMO regulations you have to be able to see the sea two ship lengths or 500 meters, whichever is less, ahead of you. That's why the container stacks gets shorter forward of the bridge on all the container ships on your illustrations.
The relevant regulations can be found here.
Incidentally it's also wrong since the Emma Maersk looks like this.
[ img ]
The dotted line from the bridge to the bow shows the sight lines that must be kept clear. As long as that line is respected you can keep stacking the boxes up. They're actually raising the bridge one level on them in order to increase their capacity.
By split layout I mean that the superstructure isn't above the engine. The Triple E is an example.

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Tobius
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 8th, 2017, 12:52 am
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acelanceloet wrote: *
Tobius, Your point of view might be wrong then.
Point by point.
Quote:
I only have expertise from a shipbuilding perspective, but docking and collission avoidance are done in different waters, at different speeds, with different objectives and with different control systems. because of that, they are also (partially) done from different places on the ship:
The maneuver problem between objects is based on speed, time, and perspective. These factors are common to any maneuver deconfliction (pass through or pass by). How fast? How much time to react? Can one see it?
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collision avoidance is done from your main control point, the pilothouse, where you have all information possible available to you: radars, watchkeepers, camera's and your ships actual behaviour information.


The maneuver deconfliction problem is best handled from main steer. Agreed. Warping in, is a different procedure altogether.
Quote:
Docking is done (partially) from the bridge wing, as you only need information about 2 things in the final stage: the position of your ship relative to the quay and the movement of your ship (in waves, wind etc) which can only be accurately judged when you have eyes seeing those.


That is, I believe, a compendium modus as to the closing speeds between a moving and a stopped object, or two objects traveling the same vector, same velocity in formation (Station keeping). Someone has to be positioned to see eyes on what the closing interval is to make the fine control adjustments and/or pass that information to main steerage control. As weird as it may sound, that is exactly what the guy lying down back there in an aerial tanker has to do while he is flying the boom to the trailing aircraft akin as to the deck officer making final adjustments to approaching his berth. Both have to control "slow approach" to make the "docking maneuver". Perspective.
Quote:
If you have the possibility of colliding with something that is so close that you can only see it from the bridge wing, it might be already too close to do anything about it, depending on the speed and conditions. But thanks for making the point that when avoiding collision, it might be a good idea to have a good viewpoint towards where your ship is going: you are actually telling us about a great advantage of the forward conning position!
That US destroyer was rammed from astern. The point I made was that you need a high perch to see where the other fellow is relative to you. That goes for radar or human eyesight. I could cite the example of Sir George Tryon who goofed and was not corrected and/or Admiral Winfield Schley who also goofed but who had someone up in the pilot house to throw it even harder astarboard past rudder safeties when the Texas, turning to port to unmask her guns almost rammed the Brooklyn (According to Schley at his court martial. It was the Brooklyn that was the actual offender, she turning the wrong way to avoid the Maria Teresa's ramming attempt . Texas threw it hard astern and escaped collision by mere meters.) Pilothouse and port wing on Brooklyn and starboard wing and topmast lookout on Texas intervened. So no Camperdown/Victoria fiasco for the USN, which should have happened if sailors' wits and helms' eyes had been duller.
Quote:
We have to keep in mind that many warships have a conning position quite far forward, as have many heavy lift ships and quite a few others. I go with Thiel's expertise here, the classic position offers advantages, but so does the forward one. In most cases the aft position is better, but there is no case whatsoever you can make for the bow conning position as terrible as you make it be. See this post earlier in this thread.
All I can say is that actual history (two quite famous examples) is against that conclusion. I could add a third. MV Stockholm and MV Andrea Doria. No-one has explained that one completely, though the bridge watch on the Andrea Doria seemed to pull a Schley (turned the wrong way) when they noticed the Stockholm and the navigator of the Stockholm, too busy with the balky radar, either did not heed the helmsman's warning or just assumed when he looked up that the Andrea Doria would clear ahead. That's 48 people needlessly killed, loss of the Andrea Doria ($30,000,000 1958 dollars), legal troubles, aplenty, and confirmation that forward lookouts do not automatically work, because the Stockholm in a fog bank posted them. The accident was avoidable. The Andrea Doria saw the Stockholm and could have turned to STARBOARD as the Stockholm followed COLREGS late and also turned starboard. This would have resulted in a pass bay or survivable side scrape. Apparently the Andrea Doria's crew failed to understand the exception to the rule which is to check aspect of the other guy's turn and counter turn away. Stockholm rammed the liner abeam starboard side, just about 2/5th forward. Andrea Doria turned into the collision. The Andrea Doria apparently saw Stockholm in time.

Personally I think Stockholm's crew relied too much on their radar which was mis-sited and which from admiralty court and US Congressional testimony none of them knew how to properly use. For example; the Stockholm's third officer/navigator set the range ring PPI indicator wrong, so that he read the radar range gating at 5 miles (It was a US made set) instead of the 15 miles he thought and assumed it was set. It also had a blind arc, which while it did not affect the accident made the radar useless astern.


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acelanceloet
Post subject: Re: Practical Nuclear Merchant VesselPosted: October 8th, 2017, 8:35 am
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Tobius, what exactly is your conclusion? I see a lot of points, none of which are replies to what I said, it is just more (more or less related) information.

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