Follow Up And Non Follow Up Steering Gear System Pdf
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It is not the function of the Board to assign fault or determine civil or criminal liability.
- Human Factors perspective on ships steering control
- Steering Gear Systems on Ships – Marine Engineering
- US5107424A - Configurable marine steering system - Google Patents
- Human Factors perspective on ships steering control
Human Factors perspective on ships steering control
As Human Factors expert I think the real human error took place long before the incident, and was not caused by the crew, but by the builders and designers. This article discusses steering controls of seagoing ships. With the help of some recent reports of grounding and collision incidents related to steering, we make an analysis of the Human Factors and safety aspects, and come up with 10 practical design guidelines.
Movement of a ship is normally controlled from the navigation bridge. On larger vessels multiple control sets of these systems can be found on several locations on the bridge: at the navigation console, wing consoles, helmsman console, DP workstations etcetera.
When the ship is sailing in restricted areas, like rivers, shipping channels and ports, the timeframe to act is often not more than a few minutes. Because of the many technical components involved, this period is usually not sufficient to analyze and solve the initial problem. Safety regulations ensure these emergency backup systems also called auxiliary control systems are present on every ship.
Incident reports show that — despite of emergency backup systems — steering control failure incidents still happen, sometimes with groundings and collisions as result:. Lawrence river in Canada, as a result of lost steering control. Investigation revealed that the ship was equipped with multiple steering control panels and several back-up control systems. One of these systems acted as override: when a small unlabeled joystick on the navigation console was touched unintentionally, it automatically took over steering control, and switched off all other steering control systems.
The bridge team was not familiar with this additional backup joystick and its specific behavior. The six-person bridge team and two pilots tried to regain control by switching between several steering control systems and steering modes, but without success. Giving full power astern and attempts for an emergency anchoring could not prevent the ship from grounding on the river bank, 9 minutes later.
Tugs were able to refloat the vessel. No casualties or damage was reported. The bridge team was not able to discover the correct configuration of switches and buttons in time to regain the lost steering control before the ship grounded. During this operation the first helmsman suddenly lost steering control.
Apparently steering control was unintentionally transferred to the second workstation too, without being noticed by the crew. Immediate attempts were made to regain steering control by switching over to an emergency steering location elsewhere on the ship. For this purpose both the bridge and emergency location have a control override button: when pressed control is instantly transferred to the nearest workstation. The crew of the emergency location pressed the big red override button, by which they successfully took over steering control from the bridge.
By doing so, in fact he took back control. So, after a few switching operations and much confusion, steering control was restored on the bridge. Ten sailors were killed. After an unintended transfer of steering control location, the system was unable to successfully inform the bridge crew which system was now in control, and how to get back to the initial situation. When the crew intentionally tried to move the steering control location, the system behaved differently than expected by the operator.
When the pilot commanded a course change, the steering system did not respond. Several attempts were made to change course by using the steering hand wheel, but without any rudder response.
Preparations were made to stop the ship by reversing the engine and emergency anchoring. Also the master was called to the bridge. He was able to quickly restore steering control by switching the system over to a backup system. However, three minutes after the initial steering failure the ship grounded. No casualties ware reported, but the hull took some damage.
Investigation revealed that one of the potentiometers of the hand wheel had failed — the one connected to the main steering gear. Before the master appeared on the bridge the crew had not attempted to switch over to the second steering system, or to use the Non Follow Up steering controls.
Both backup systems worked as designed. In a following investigation the authorities reviewed bridge crew knowledge about steering backup systems on 8 ships of different sizes, owners and nationalities.
On 6 vessels the crew was not fully familiar with the use of emergency backup steering systems or the NFU mode. Based on a design experience of 20 years and over 25 large vessels, we have no doubt there are many more incidents with similar conclusions. In two of the above cases steering control was lost because the crew unintentionally switched the system to another mode or location.
The system failed to inform the user which workstation or set of controls was active, and how to switch it back to the previous state. There seems to be no standardized setup or user interface for steering controls on a ship. As a result, the crew has to familiarize with each individual ship they work on. Differences in design can be subtle, and sometimes we find exactly the same physical controls and labels, but with different functional behavior.
Since steering equipment is very reliable, bridge crews do not have much experience with using backup systems. And if they need to, it is possible that their knowledge of the current ship get mixed with memories of other vessels, that might have a slightly different setup.
Some companies have an internal standard, but in many cases the steering control design is based on a proposal of the steering equipment vendor, system integrator or yard. So even with a company standard, the actual controls, and control panel arrangement may vary from ship to ship. A complicating factor is that on many ships movement control is divided over several systems, usually supplied by different makers. All these systems may be linked in certain steering modes or controlled separately in other modes.
Each of the systems and control panels may use a different vocabulary to address emergency backup systems. Labeling of the controls is often rudimentary or ambiguous and provides not much information about their functionality and relation with other controls. In case of darkness: illumination of buttons may be OK, but the overall panel arrangement is often hard to see in the dark.
As a result, the crew is not always confident about using switches for engaging backup systems, as they are not sure which systems will be affected and in what way. This is a type of backup device that automatically takes over control whenever a dedicated override tiller or joystick is touched — regardless of the setting of other steering mode selectors and steering location selectors.
A pitfall of this concept is that the system assumes that the operator will only switch to override mode as result of a deliberate, well-thought action — which is not always the case.
Sometimes an override is touched unintentionally, without the operator being aware of it. The system also assumes that the user is fully aware of how the override affects to all other components in the steering system setup. Again this is not always the case, and can be complicated anyway, in case multiple steering control modes and locations are present. On these vessels and many others it is possible to take control by using the override joystick, whereas the master steering mode selector switch is still in the FU FollowUp , NFU NonFollowUp , or Autopilot position.
As a result the operator gets conflicting information, and interpretation errors are inevitable. Another interesting factor is time. All three incidents took place within 9 minutes, two of them in just 3 minutes. This is barely enough to get a good overview of the problem at hand, and in most situations it is not sufficient for a systematic analysis of the problem. As a consequence the amount of backup systems should be limited, preferably to one, since engaging and testing each of the backup systems will take a few minutes, because of latency in the control systems and inertia of the steering gear and ship.
The steering system is often not the only means of movement control available. Many vessels can also use bow thrusters or allow independent control of propeller thrust. Using these systems, which are in fact no part of the steering gear, may be more effective to control the ships movement than try to restore rudder control, when the available time is very limited.
This may have technical reasons: a bow thruster unit may need some start-up time, and many ships with a fixed propeller setup need to slow down, stop and restart the engine in reverse, before they can effectively reduce speed.
Commercially driven behavior can also be a relevant factor, making officers reluctant to reduce the vessels speed, as long they see alternative ways to regain control. Below are 10 design guidelines for steering control on ships, based on Human Factors principles. Several other terms are also commonly used, like main, master, auxiliary, backup, etcetera, but these are less self-explaining. A Follow Up FU input device hand wheel or tiller is rotated by the user to a certain rudder angle setpoint.
The steering control system will then activate the rudder gear to rotate in the right direction and stop automatically when the chosen angle setpoint is reached. In this case the rudder is moved as long the user holds the control device. When the device is released, the rudder motion stops. During this process of checking, the user can not focus entirely on the ships navigation. Sometimes we see that NFU input devices are used on additional workstations, like bridge wing consoles.
Reason to apply NFU controls here, is that the device is spring loaded: it is only active when manually operated and when released it jumps back into the neutral position. Therefore a NFU control device does not need a take-over protocol for switching over, and is technically simpler to make.
As mentioned before, in case of a steering failure there is usually no time to analyze the source of the malfunctioning. By using a direct NFU mode, most of the technical control components are bypassed. We recommend using clearly distinct input devices for normal steering control and emergency control.
This helps the operator to realize that both input devices are connected to separate, independent steering systems. Be noted that the SOLAS regulations allow to control both normal and emergency by one combined control device.
Recommended is to use one and only one master steering mode selector. Main reason for this is that in case of lost steering control, the user should not have to wonder which combination of switches and dials would engage the emergency mode: there is only one switch, and that is also the one the operator is already most familiar with.
An exception to this rule can be made for touch screen based master steering mode selectors. If redundancy of the touch panel is regarded necessary, a duplicate can be used, as long as the functionality is identical, and the duplicate is located near the first one. It may be expected that a simple setup will be simple in design too. However, this is not always the case.
Below is a quick overview of challenges designers and engineers have to face:. The available amount of time to take back control will increase drastically: a quick and simple way to improve safety. Please let me know, and I will dedicate another article to your question. Home Contact. Toggle navigation. Background Movement of a ship is normally controlled from the navigation bridge.
Steering Gear Systems on Ships – Marine Engineering
It is not the function of the Board to assign fault or determine civil or criminal liability. This report is not created for use in the context of legal, disciplinary or other proceedings. See Ownership and use of content. While proceeding downbound on the St. Lawrence River under the conduct of a pilot, the vessel lost steering control and ran aground at on the Battures de Gentilly, 1.
Bassett, Noel L. The motor vessel American Republic is a Great Lakes self-unloading dry bulk carrier designed and built for operation between Lorain, Ohio and the head of navigation on the Cuyahoga River in Cleveland, Ohio. In order to safely navigate the Cuyahoga River on a regular basis, the vessel was designed with twin screws, Kort nozzles, four flanking rudders, four steering rudders and bow and stern thrusters to enhance maneuverability. In addition, a novel pilothouse arrangement was incorporated into the design to optimize visibility and vessel control. The design of the propulsion and steering system is discussed and an evaluation of the vessel's operation is presented.
Effective date : Year of fee payment : 4. Year of fee payment : 8. Year of fee payment : A ship steering system has a multiplicity of selectable steering stations. Steering stations are selected through a multiplexer controlled at a command steering station. The steering system is operable from the command steering station in a plurality of modes, which includes auto-pilot, helm full-follow-up , and tiller non-follow-up.
The JAS-JO1-NFU is a non-follow up lever controller for the. NavPilot series of FAPE: Jog-Lever Remote Control (Non Follow-Up. Type) with Processor Junction Box you to steer by selecting varying amounts of port/starboard.
US5107424A - Configurable marine steering system - Google Patents
Brochures Table of Contents 1. Jastram Modular System Concept ………………………. Electric Steering Control System ……………………….. Rudder Angle Indicator System ……………………….. Marine Hydraulic Helm Pumps ………………………..
All requirements for
Human Factors perspective on ships steering control
Click Here To Download Now. Quarter Masters kept watches and took turns on the helm all day when at sea. This practise continued until automation took over in the field of navigation. Auto-Pilot system is considered as one of the most advanced and technically sophisticated navigational equipment tools on ships. Auto-Pilot is synchronised with the Gyro Compass to steer manually input courses, with reference to the gyro heading. Auto Pilot steers the manually input course by controlling the steering gear to turn the rudder in the required manner.
Панк кивнул. - Tenia el anillo. Он получил кольцо. До смерти напуганный, Двухцветный замотал головой: - Нет. - Viste el anillo. Ты видел кольцо. Двухцветный замер.
Беккер был смуглым моложавым мужчиной тридцати пяти лет, крепкого сложения, с проницательным взглядом зеленых глаз и потрясающим чувством юмором. Волевой подбородок и правильные черты его лица казались Сьюзан высеченными из мрамора. При росте более ста восьмидесяти сантиметров он передвигался по корту куда быстрее университетских коллег. Разгромив очередного партнера, он шел охладиться к фонтанчику с питьевой водой и опускал в него голову. Затем, с еще мокрыми волосами, угощал поверженного соперника орешками и соком. Как у всех молодых профессоров, университетское жалованье Дэвида было довольно скромным. Время от времени, когда надо было продлить членство в теннисном клубе или перетянуть старую фирменную ракетку, он подрабатывал переводами для правительственных учреждений в Вашингтоне и его окрестностях.
PDF | This paper presents aspects of the steering gear onboard a Download full-text PDF a non-follow up back-up control system for.
Сьюзан ничего не ответила. - Я вижу, ты выдающийся командный игрок. Может быть, можно взглянуть? - Он встал и начал обходить круг терминалов, двигаясь по направлению к. Сьюзан понимала, что сегодня любопытство Хейла может привести к большим неприятностям, поэтому быстро приняла решение.
- Единственное различие - их атомный вес. Это и есть ключ. Давайте оба веса. Мы произведем вычитание.
Его дыхание стало ровным. - Сьюзан. - Голос его прозвучал резко, но спокойно. - Тебе удалось стереть электронную почту Хейла. - Нет, - сконфуженно ответила .
Мидж подтвердила свои слова коротким кивком.