# What to converge on Damage Stability?

Discussion in 'Stability' started by mactavish, May 22, 2022.

Tags:
1. Joined: Sep 2014
Posts: 19
Likes: 1, Points: 3, Legacy Rep: 10
Location: philippines

### mactavishJunior Member

Hi Mates,

I have a question regarding the damage stability.

I know there are two methods:
- Loss of buoyancy method

My question is. What do we have to converge on the calculation in order to get the Damage stability right?

Is the iteration to converge the CoG and CoB until they are aligned to each other both for trans and longi positions? is that where you stop the calculations iteration?

2. Joined: Aug 2004
Posts: 3,686
Likes: 1,070, Points: 113, Legacy Rep: 2040
Location: Port Orchard, Washington, USA

### jehardimanSenior Member

When conducting a calculation for damaged stability, whether inside out (lost buoyancy) or outside in (added weight), there are additional criteria besides necessary rigid body physics.
1) There is a minimum GM at all stages of flood-up including free surface (c.f. the MV ROCKNES capsize).
2) There is a minimum area under the righting curve for all stages of flood-up. (c.f. MV TRICOLOR)
3) Conservative calculation in either the ever-buoyant volume or the Permeability

3. Joined: Sep 2011
Posts: 7,297
Likes: 676, Points: 123, Legacy Rep: 300
Location: Spain

### TANSLSenior Member

By calculating the intact stability at any loading condition you calculate the equilibrium floatation, for which you also need to compromise on the exact positions of both points. Use the same accuracy in damage stability calculations.

jehardiman likes this.

4. Joined: Aug 2004
Posts: 3,686
Likes: 1,070, Points: 113, Legacy Rep: 2040
Location: Port Orchard, Washington, USA

### jehardimanSenior Member

Yes, the whole idea of Center of Permeability is fraught with issues.

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.