Radii of gyration - Added Mass & Drag - CALM.dat

Hi Ari,

The added mass and drag input you are showing are for the buoy.  The .32*beam you made a comment on is common for a barge.

This set of files are based on a project.  You can see that in later lines the added mass and drag defined with the tubular will also be used.

The values used here are added to those inherent in the beam definition.  They were added to tune the response. 

I hope this helps.

Georgina Maldonado

Hi georgina,

can you explain how to calculate the radii of gyration for misc weight? example:

Rocker Arm, Grillage, etc.. and does this value can be obtain from SACS?

*skid 51.99 0.00 12.30
#WEIGHT *skid 428 0 0 0 -ldist 9.8 94.8 -cat skid $ 11.63 14.16 17.91
$
*r_arm 0.00 0.00 12.30
#WEIGHT *r_arm 400 0 0 0 -ldist 38.00 88.00 -cat r_arm $ 11.63 14.16 17.91

Hi Naim,

There are many sources on the internet for computing the radii of gyration.

https://en.wikipedia.org/wiki/Radius_of_gyration

If you are asking about the values in the skid and the r_arm that you put in the question I do not know why they are using 0.

It could be that the weight is small compared to the size of the vessel. 

I will bring also ask how to calculate this in SACS.

I hope this helps.

Georgina Maldonado

Hi georgina, thank you. There’s a spreadsheet named “radius of gyration” in moses directory. Can i used this to calculate weight gyration for misc items previously mentioned? Or it is only for barge and tanks. Thanks

Good afternoon Naim,

the spreadsheet you mentioned is not barge-specific. With or without tanks in place you can use it, the physics are not specific to MOSES or any analysis. 

You can edit the spreadsheet accordingly to suit your own needs. Remember that ultimately you are responsible for your input.

I hope this helps
Spiro