Learning Forum

[nguyenthithanhdiep1994]

Hello everyone,

I am currently researching the buoy with mooring lines. The configuration of the setup is below. The buoy is connected with a sonar sensor and mooring lines.

The mooring line includes 4 components. The 2nd component of the mooring line consists of a buoy. How can I define the mooring lines with 4 sections and a buoy?

I hope to receive your advice.

Thank you so much.

[Ingrid M]

Hello, 

The nonlinear caternary allows you to do this; you can create for the same cable definition different sections with the same (or different) section types, length and specify whether this particular part of the cable is expected to touch down on the seabed.

I hope this helps.

Ingrid

[nguyenthithanhdiep1994]

Dear Ingrid M,

Thank you so much for your response. I defined it following the AQWA manual. However, it has a problem with the weight/Unit length input. One of the mooring line sections has a lightweight cable with a Mass/Unit Length of 0.478 kg/m in section 2. And I can define this section's properties. Is there any way to create a lightweight cable?

[Ingrid M]

Hi,

for catenaries, the weight should be at least 1.025 kg/m2 (your density devided by 1000). You can also increase the equivalent cross-sectional area so that the overall buoyancy is correct.

I hope this helps.

[nguyenthithanhdiep1994]

Thank you so much for your response. I solved this problem. However, I have another problem with the yaw motion response in the time domain. I simulated only the case of wave direction of 180 degrees. However, the ship rotated continuously 1 unreasonable when the wave direction was 180 degrees as shown in the picture below. Theoretically, when the ship operates 180 degrees, yaw motion is almost non-existent. Is there has any way to reduce the yaw motion such as adding the torsional stiffness or something?

[Ingrid M]

Hi,

yes, to account for the viscous effect, you might want to add drag coefficients on the hull. Depending on the shape of your vessel, this could be along the degree of freedom that will be the most affected, such as in yaw, in sway of you have a slender hull, etc.. 

I hope this helps.