Stability after tank reduction

[jimmymc90]

I am looking for help after reducing the capacity of 6 fuel tanks from 140m3 to 90m3. This area where the fuel was previously is now a void space which provides double hull protection for the ship. There has also been 50 tonnes of added steel due to the void space. This is the total added steel for all 6 tanks

What I need help with is finding the stability values for the new design. I have the ships hydrostatic data for the origional ship however i am not allowed to use this information and have to calculate the stability data myself. I have currently calculated the ships new lightweight and displacement and its corrisponding draught ( that i was allowed to take for the hydrostatic data)

I should also point out that I am only required to calculate the ships stability in its lightweight condition.

I have attached my pictures of my 3d models to help you understand better. These are only for 2 tanks. All 6 tanks are the same dimensions and the same distance from the centreline of the ship.

How would you go about calculating the ships stabilty after this change in design?

Also any help on how to do a GZ curve would be helpful

Thanks,
James

[Ad Hoc]

Originally Posted by jimmymc90

I have the ships hydrostatic data for the origional ship however i am not allowed to use this information and have to calculate the stability data myself.

Then it is a simple matter of assuming the wall sided formula, and doing the basic BM = I/V calculation.

[jimmymc90]

Thanks Ad Hoc

Is there away to calculate what the draft would be on a ship Fwd and Aft if I have the Draft at C.F and I also have the weight distrubution curve?

[Ad Hoc]

Originally Posted by jimmymc90

Thanks Ad Hoc

Is there away to calculate what the draft would be on a ship Fwd and Aft if I have the Draft at C.F and I also have the weight distrubution curve?

The "old fashioned" way. The way i was taught before computers came along

Measure, off a piece of paper either supplied (of the hull shape) or you make yourself by simple sketch, and Simpsonise the values you lift off.

The rest is "simple" naval arachitecture. Any book will show you how to obtain drafts from data and LCF. Being a student I assume you have access to these?