DETERMINING CHAIN LENGH BASED ON PRETENSION VALUE (MOSES)

Hi,

I would like to ask how to find the length of chain based on given pretension value and anchor radius. Understand that moses are required to input the length i,e:

$CLUSTER 1

$ ------- SET OF MOORING CHAIN PARAMETER -----------------
$CHAIN = R4 STUDLESS
&SET WDEPTH = 63 $$ WATER DEPTH
&SET CDIA = 105 $$ CHAIN DIAMETER (MM)
&SET WPLEN = 0.221 $$ CHAIN WGT PER LENGTH (MT/M)
&SET CLEN = 600 $$ CHAIN TOTAL LENGTH

~201 B_CAT %CDIA% -DEPANCHOR %WDEPTH% -LEN %CLEN% -WTPLEN %WPLEN%
~202 B_CAT %CDIA% -DEPANCHOR %WDEPTH% -LEN %CLEN% -WTPLEN %WPLEN%
~203 B_CAT %CDIA% -DEPANCHOR %WDEPTH% -LEN %CLEN% -WTPLEN %WPLEN%

CONNECTOR ML01 -ANCHOR 180-65 600 ~201 *101
CONNECTOR ML02 -ANCHOR 180-70 600 ~202 *102
CONNECTOR ML03 -ANCHOR 180-75 600 ~203 *103

&TYPE SETTING PRETENSION VALUE AT EACH LINE
$ NAME PRETENSION
&connector ML01 -a_tension 76.76
&connector ML02 -a_tension 76.76
&connector ML03 -a_tension 76.76

Parents

  • Once you apply tension using the "&connectorn ml01 -a_tension" command, MOSES will adjust the lengths to achieve the desired anchor tension. To obtain the final length, you can utilize the string function "&connector(ml01 -length)". Additionally, you can utilize the "&status spread", "&status g_connector", and "&status line" commands to output the lengths of the lines.

    Answer Verified By: Naim Hassan 

  • Dear Rahul, this may be a different question, but how to perform full dynamics mooring analysis, understand that moses run quasi dynamic analysis. but in deepwater the chain inertia itself is considered and will effect the exursion of the vessel. is there a sample i can refer?

  • Hi Naim,

    Chain inertia is considered in the analysis as you provide the weight/length properties in the class definition. Additionally, you have the option to include the added mass (-AMASDIAMETER) and drag (-DRAGDIAMETER) in the line class definition.

    To incorporate line dynamics into your analysis, you can utilize the ROD connector class. There are numerous samples in the "mooring" (hdesk>>runs>>samples>>mooring) folder that have the rod element class defined. Please feel free to reach out if you have any further questions.

    Thanks,

    Rahul

    Answer Verified By: Naim Hassan 

Reply
  • Hi Naim,

    Chain inertia is considered in the analysis as you provide the weight/length properties in the class definition. Additionally, you have the option to include the added mass (-AMASDIAMETER) and drag (-DRAGDIAMETER) in the line class definition.

    To incorporate line dynamics into your analysis, you can utilize the ROD connector class. There are numerous samples in the "mooring" (hdesk>>runs>>samples>>mooring) folder that have the rod element class defined. Please feel free to reach out if you have any further questions.

    Thanks,

    Rahul

    Answer Verified By: Naim Hassan 

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