Looking for some more stability advice from you clever people

[jimmymc90]

I have posted a couple of times for some help on here already and have got some good advice.
Im basically redesigning a ro-ro ferry to comply with regulation 12a. I have currently removed 300 tonnes of fuel and replaced this with a double hull under the six fuel tanks. The total added steel was approx 50 tonnes. From this I have worked out the ships new deadweight, lightship and draft however im not sure how to go about proving the ship is still stable. I have all the parent ships data and have done been taught a bit of nav arc before Im just getting abit confused from having to work backwards from the fugures I have.

im assuming I will have to calculate the fuel tanks new centres LCGs and the free surface effect etc but Im not sure what else.

as always thanks for any advice
James

[gonzo]

Can you add ballast to equal the fuel you removed?

[Ad Hoc]

James

Do you have the stability booklet?..ie do you have the cross curves of stability?

[jimmymc90]

cheers for your replies guys,
Gonzo, I have been told to try keep away from simply adding ballast to replace the fuel.
Ad hoc I have the statical stabilty curves of each load condition but obviously these conditions have now changed slightly, is this what you are talking about?

[Ad Hoc]

Originally Posted by jimmymc90

Ad hoc I have the statical stabilty curves of each load condition but obviously these conditions have now changed slightly, is this what you are talking about?

From the weights on and weight off table....if you make sure you do this with the VCG and LCG too, you end up with the new displacement, VCG and LCG.

From the curves of stability, you can calculate the stability using the KN data, at the new displacement and LCG, VCG.