Hello, I have a very big problem regarding this Limit KG study that gives me an inconsistent table and I would like to know how to solve it.
(XY Overseas 53).rar
Hi Jose,
Thank you for reaching out. Could you perhaps explain what you mean by "inconsistent table"? If you can give a table comparison that supports your claim that it is inconsistent, that would be helpful.
I apologize that your attached image (table) is difficult to read. Did it cause a mistake during analysis?, if so, kindly share a screenshot.
It would be preferable if you could submit a support ticket here so that we could investigate your situation further and respond right away.
You can read about Convergence Error for Limiting KG Analysis on this Wiki.
Regards,
Jochelle
I mean that the KG limit table is not correct. nor lowering the VCG. I sent you the file to see if there is a way to solve it and explain how.
Hello Jose,
I had a look at your design. In your case, you are setting up criteria, which are unable to pass and hence the convergence error.
In your case, it is impossible to find a VCG where all criteria pass. For example, if you run the Large Angle Stability of Return condition, the angle of vanishing stability is 80 degrees, and the required angle you set according to ISO 12217-2:2002(E) you set to 130 degrees. No matter how low you set your VCG, you won't be able to achieve the required 130 degrees.
What I recommend is to review all set criteria and make sure that the model is able to pass the criteria with set VCG.
I hope it is more clear now.
I highly encourage you to have a look at Stability Manual to read more about Limiting KG analysis.
Aleksandra
Hello Aleksandra, nice to greet you again.
Would I have to add more bottom weight to solve the problem, or a higher freeboard?
I would start with making sure that your surfaces are going to the centerline, because your design has a 0.002m offset:
Then run Large Angle Stability and create a loading condition where your criteria are met or almost met. Now, none of your loading conditions meet your criteria. The tricky part with catamarans is that they are very stable but only to a certain heel angle, after that, they become very unstable.
In order to meet the criteria you need to increase your vessel's stability. There is no right or wrong way to do it; it depends on the design. You could increase the beam (but it decreases the range of the stability, so in your case, it probably will not be the solution), increase the draft, and move VCG down. Also as you said increasing freeboard will help.
Then once you have the Large Angle Stability analysis successfully performed, you can run a limiting KG analysis.
I would also advise you to review the criteria and make sure that you are using only the necessary criteria.
I hope it helps.
I've tried everything and it doesn't go above 93 degrees. I tried experimenting with the bottom completely full of tanks and it still
doesn't read more than 98. It seems unrealistic to me to achieve that small value. Do catamarans require 130 degrees of heel?
I want to clarify that the experiment was carried out in two boats.
This is a design generated by maxsurf and it also gives me the same error. I don't understand whyUntitled.rar
Before using any criterion in MAXSURF Stability, you need to review it and make sure that it is set to your design. The minimum angle of vanishing stability of 130 degrees is very high, but it depends on the Design Category according to ISO 12217.
I refer you to ISO 12217-2 International Standard. You need to check the regulations and make sure that the regulations you apply refer to your design.