Error when coupling MoorDyn and MATLAB for the OC3 Hywind mooring system

Hello everyone,

First, I want to share with you some information and second i have a problem if you could help

I was working on Windcrete, the spar platform designed for supporting the IEA 15 MW. However, i could not find any information regrading the design of the tower. (it has been said in D1.3 “Public design and FAST models of the two 15 MW floaters” that the tower is made from concrete). I run a preliminary fatigue analysis considering normal conditions (Hs=2m, Tp=10s, wind speed =11 m/s) and obtain a tensile stress of order 5 MPa which is equal to the tensile strength of the concrete. That was surprising !!! meaning that the concrete will fail. I talked with the designers and they said they could not share the design of the tower but an initial compression is applied to the tower so the concrete will not fail ! (they did not mention that in the technical report). I was obliged to move to OC3 Hywind where the floater and the tower are made from steel. So be aware when dealing with Windcrete !!

Second, i succeeded to couple MoorDyn with MATLAB when using the mooring system of Windcrete (crowfoot mooring system). When i wanted to switch to OC3 Hywind, i got errors and i did not find out why although i was using the same input file of Windcrete (I just change the numerical values) and the same script also ! I dont know where is the problem. If someone could help

Here are the following input files for MoorDyn for Windcrete and OC3 Hywind respectively

Best Regards,


Dear @Riad.Elhamoud,

What error are you running into?

Best regards,

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Dear @Jason.Jonkman

Thank you first.

In fact, MATLAB stops suddenly. It does not give me any errors (maybe i could try to find out the problem). The figure below shows what i’m getting:

Best Regards,


Hi Riad,

A key difference between those two mooring lines is that there are 3 versus 6 coupled (or “vessel”) points. Depending on what MoorDyn functions you are calling from Matlab, it probably means that in one case you need to pass data sized for 3 points, while in the other case you need to pass data sized for 6 points. I’d suggest checking to make sure that the arrays going between Matlab and MoorDyn are all sized appropriately for the scenario.


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Thank you for your response !

I will try to make sure that MATLAB talks to MoorDyn correctly (same array size).

But there is something i notice when coupling MoorDyn with MATLAB: in fact, for any mooring configuration that contains node of type connect, it works perfectly !

However, when the nodes are of the types fix and vessel only, it won’t work and MATLAB stops suddenly !!!

So, what i am thinking to do after checking the array dimension, is maybe i could add connects node to OC3 Hywind. What do you think ?

Best Regards,