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Ikari-ing(Risk Assessment Application for Dragging Anchor)

  • "Risk Assessment Application for Dragging Anchor"is a system which simply estimates risk level of dragging anchor while anchoring based on the basic ship information (ship types/principal particulars) and the marine weather forecasts.


Outline

A ship anchored in rough weather is subject to wind pressure forces from strong winds and wave drift forces from rough waves and swells. In addition, fluid reaction forces (maneuvering hydrodynamic forces) produced by ship motion and fluctuating tension of the anchor chain caused by the ship's movements may also contribute to violent slewing motion.
The IKARI–ing simulation program calculates risk of anchor dragging by taking into account the above–mentioned external forces acting on the ship (wind pressure forces, wave drift forces, anchor chain tension, and maneuvering hydrodynamic forces) to estimate the swing motion.
For maneuvering hydrodynamic forces and wave drift forces, IKARI–ing's estimation method applies experimental results obtained from water tank testing using model coastal tankers and coastal ferries, two representative types of non–international coastal trading vessels. Wind pressure forces are estimated using a method proposed by the National Maritime Research Institute (NMRI). For anchor chain shape and tension, an estimation method that calculates the static catenary is used.

Anchor risk
IKARI–ing is available in two versions: PC and Web application. The PC version can be downloaded from NMRI's download website. The Web application can be used from the NMRI Cloud. Both versions are free.
IKARI–ing was developed by NMRI as part of research commissioned by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT)'s FY2020 supplementary budget project "Emergency Measures to Prevent Anchor Dragging Accidents."

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Interface
IKARI–ing (Web Application Version) can be used as a Web application on smartphones. The Web interface has three parts: the Main screen, Input Interface, and Output Interface. The Main screen includes links to pages such as weather and marine forecast sites and the Japan Coast Guard's anchor dragging prevention portal site.
In the Input Interface screen, you can choose between Simple Mode, which has reduced input parameters, and Advanced Mode, which performs the same calculations as the PC version. In the Output Interface screen, you can view the risk level of anchor dragging for the input values and the change in risk of anchor dragging depending on different lengths of extended anchor chain and wind speeds. IKARI–ing (Web Application Version) executes simulations in the cloud and can be used on any smartphone regardless of its technical specifications.

Main screen

Top image

Input Interface: Simple Mode

Simple Mode

Input Interface: Advanced Mode

Detail mode

Output Interface

Result

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How to Use
As an example of using IKARI–ing, we assess the risk of anchor dragging of a 499GT tanker.
Accepting Terms of Use

Main screen

Main screen

First, tap "Start Risk Assessment Application for Dragging Anchor" on the Main screen.

Terms of Use Acceptance screen

Terms & Conditions Acceptance

A screen displaying Terms of Use appears. Read the Terms of Use.

Terms of Use

Terms of Use

It is necessary to accept the Terms of Use in order to use the Risk Assessment Application for Dragging Anchor.

Terms of Use Acceptance screen (after selecting the "I Agree..." checkbox)

I Agree

Select the "I have read and accepted Terms of Use" checkbox to accept the terms of use. Then tap "Forward to Risk Assessment Application for Dragging Anchor" to proceed to the Input Interface screen.

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Input Parameters in Simple Mode
In the Input Interface screen, you can choose between Simple Mode, which has reduced input parameters, and Advanced Mode, which performs the same calculations as the PC version.

Input Interface: Simple Mode

Simple Mode

Compared with Advanced Mode, Simple Mode has reduced parameters. This allows you to quickly assess risk level of anchor dragging.

Initial Configuration screen

Simple Mode

First, start initial settings.
Select Ship Type from the pull–down menu. If the applicable ship type is not listed, select ship type whose shape is the most similar to your ship's.
Next, select the value for Gross Tonnage from the pull–down menu. If you are unsure about the ship's gross tonnage, select the amount that seem to be the closest to your ship.

Initial Configuration screen

Simple Mode

After selecting Ship Type and Gross Tonnage, tap the "Apply" button.

Ship information screen

Simple Mode

IKARI–ing automatically fills in parameters for the ship information, projected area of the wind pressure forces, and anchor chain information. Confirm the automatically filled parameters and correct any values that differ from your ship's information.

Anchorage Information screen

Simple Mode

You have input all ship parameters. Next, input parameters related to anchorage information, weather and sea state information, and ship conditions.For Anchorage Information parameters, select Sea bottom sediment (Sand or Mud) and the Anchoring Method (Single anchor mooring or Twin–anchor mooring)

Weather & Sea State Information screen

Simple Mode

You can use the Simple Estimation function for the Wave Period parameter in weather and sea state information. If you are not sure about the wave period in anchorage, select the Simple Estimation checkbox. IKARI–ing will automatically calculate the Wave Period for you. Note that the estimated Wave Period assumes the wave period during rough weather conditions, such as during a typhoon.

Ship Conditions screen

Simple Mode

In the Ship conditions, enter the ship's draft and heading.

"Calculate" button

Simple Mode

After you have input all parameters, tap the "Calculate" button. The parameters are validated.If corrections are not needed, the "Calculating..." message is displayed.

Error message

Error message

If there are invalid parameters, a warning message and the invalid parameters are displayed. Correct the parameters as instructed by the warning.

Calculation in progress message

Calculating

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Input Parameters in Advanced Mode
Advanced Mode allows you to assess risk level of anchor dragging with accuracy similar to IKARI–ing (PC Version).

Input Interface: Advanced Mode

Inituial settings

First, start initial settings.
Select Ship Type from the pull–down menu. If the applicable ship type is not listed, select ship type whose shape is the most similar to your ship's.
Next, select the value for Gross Tonnage from the pull–down menu. If you are unsure about the ship's gross tonnage, select the amount that seem to be the closest to your ship.

Initial Configuration screen

Tap apply

After choosing Ship Type and Gross Tonnage, tap the "Apply button. IKARI–ing automatically fills in parameters for the ship information, projected area of wind pressure forces, and anchor chain information. Confirm the automatically filled parameters and correct any values that differ from your ship's information.

Ship information screen

Ship information

Surface Area Affected by Wind Force (Fully Loaded Hull)screen

Surface area

Anchorage Information screen

Anchor and Anchor chain

You have input all ship parameters. Next, put parameters related to anchorage information, weather and sea state information, and ship conditions.

Anchorage Information screen

Anchorage

For Anchorage Information parameters, select the Sea bottom sediment (Sand or Mud) and the anchoring Method (Single anchor mooring or Twin–anchor mooring )

Weather & Sea State Information screen

Weather and sea state

Ship Conditions screen

Ship condition

In the Ship conditions, enter the ship's draft and heading.

"Calculate" button

Start Calculation

After you have input all parameters, tap the "Calculate" button. The parameters are validated.

Error message

Error message

If there are invalid parameters, a warning message and the invalid parameters are displayed. Correct the parameters as instructed by the warning.

Calculation in progress message

Calculating

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Output Interface

Risk level of anchor dragging

Result

After calculation is completed, the Output Interface screen is displayed. The risk of anchor dragging at one of three levels — High, Medium, or Low — is displayed. Also displayed is a graph showing the change in risk of anchor dragging depending on different length of extended anchor chain or different wind speeds.

Risk of anchor dragging for different lengths of extended anchor chain

Risk Length

Tap the graph name to switch between the two graphs.

Risk of anchor dragging for different wind speeds

Risk Wind

Warning message if the anchor dragging risk is high

Warning message

The bottom of the risk of anchor dragging assessment results shows the input parameters and warning message if the risk of anchor dragging is high.

Input parameters

Input parameters

"Return to Input Parameters" button and "Return to Menu" button

Return to button

If you wish to update the input parameters and recalculate the risk, tap the "Return to Input Parameters" button.

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Anchoring method

Single anchor mooring(Possible to select)

Single anchor mooring

  • Anchor can be weighed easily for quick anchorage changing.
  • Easy to switch to other anchoring method such as steady anchor or twinanchor mooring according to the wind direction change.
  • The anchor holding is weaker than other anchoring methods.
  • Source of reference
    Japan Coast Guard Guidelines for preventing anchor dragging

Twin–anchor mooring(Possible to select)

Twin-anchor mooring

  • The effect of reducing yawing/swaying is highest when anchor chain angle is set to 45-60 degrees and the force on the anchor will be reduced by nearly 40%.
  • Anchor may foul by the wind direction changes.
  • Fouled chain is difficult to fix on ship's own.
  • Weighing of anchor is difficult in the strong wind.
  • Source of reference
    Japan Coast Guard Guidelines for preventing anchor dragging

Single anchor mooring with snubber anchor(Not possible to select)

Single anchor mooring with snubber anchor

  • Effective to reduce bow yawing/swaying.
  • The snubber anchor is effective to reduce yawing/swaying by halves and to reduce the force on the anchor by 30–40%.
  • Effective in sea areas where wind is not very strong.
  • Anchor may foul by the wind direction changes.
  • Fouled chain is difficult to fix on ship's own.
  • Weighing of anchor is difficult in the strong wind.
  • Source of reference
    Japan Coast Guard Guidelines for preventing anchor dragging

Two–anchor mooring(Not possible to select)

Two-anchor mooring

  • Anchor holding is enhanced.
  • Effective in strong wind and current from the same direction.
  • Anchor may foul by the wind direction changes.
  • Fouled chain is difficult to fix on ship's own.
  • Weighing of anchor is difficult in the strong wind.
  • Source of reference
    Japan Coast Guard Guidelines for preventing anchor dragging

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Adding IKARI–ing to the Home Screen
If you use an Android or iOS smartphone and Chrome (Android) or Safari (iOS) as the browser, you can add IKARI–ing to your smartphone's Home Screen as a Progressive Web Application (PWA). You can then launch IKARI–ing directly from your Home Screen.
Android

Add to Home Screen

Tap the Install banner.

Tap install.png

Tap "Install."

IKA-RING App Icon

The IKARI–ing app icon is displayed on the Home Screen.

IKARI-ing kun

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iOS

Tap browser's menu

Tap the browser's Menu button.

iOS Add to Home Screen

Tap "Add to Home Screen."

Tap add

Tap "Add."

IKA-RING icon

The IKARI–ing app icon is displayed on the Home Screen.

IKARI-ing kun

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These are the instructions on how to use IKARI–ing, the risk of anchor dragging Assessment System. If you have any questions, use the Contact Us page on the NMRI Cloud website.
For instructions on how to use IKARI–ing (PC Version), refer to the PC version download site or the instruction manual included with IKARI–ing (PC Version).

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