Assesing for Racking of a pontoon boat in waves with a moon pool.

Hi All,

Sorry, took a few days off for the holidays. This is a university project. It's a part of my masters thesis.

I just whipped up this brief FEA study report I did on the frame I am designing. Looks like everything checks out initially. Still have to do some convergence studies and such to check the FEA. Also I'm not claiming everything in this report is my own work or is 100% accurate yet. I still need to cite the DNV GL equations and figures and this is just a rough draft to let you see what I am doing.

 

"The frame is to be made of steel tubes with a yield strength of at least 345 MPa."

I did not see the size and wall thickness of the subject tubing in the report draft. Did I miss this information?

 

It might have been in a previous post, but you are correct it should be in the report. They are 10x6x0.25 RHS.

 

You need to demonstrate that you are complying with Class rules. Thus the 345MPa is way way over class allowable limits.
You need to check the rules for their design allowable stresses.

For the MP moment, the midships (centre) should remain at zero displacement. Similarly with Mt the centreline.

 

A couple more questions for the awesome folks on here.

Can anyone point me towards the DNV GL rules for calculating allowable stresses?

I'm also looking for something that can tell me how much reserve buoyancy I should have.

Also any regulations of foam filling the pontoons or installing bulkheads for the event of a pontoon puncture?

Thanks!

 

Since you're a student, the objective of your exercise is to read and learn for yourself where these aspects of design and limits are in the rules. Otherwise how much learning are you doing if done so by others?

However you can find in:

Pt.2 Ch.2 Sec.9 Table A2 & Pt.Ch3 Sec.5 Table J2
and
Pt.3 Ch.3 Sec.1 A202

Pt.1.Ch.2.Sec.2.A301 table A1

But it is also for you to decide what is appropriate for the design.

Class rules are there as the base minimum requirements, NOT the maximum.