ShipSafe – Trim and Stability Calculator

Description

***06-Dec-2021*** – ShipSafe is currently available for Cargo Vessels and Pontoon Barges covering IMO General Stability Criteria.

Future version for Passenger Vessels will be released soon.

Welcome to ShipSafe V1.2 – the excel based Ship Trim & Stability Calculator for sea-going Cargo Vessels. This app can be used to

• Calculate Draft and Trim of a Vessel
• Evaluate Stability – IMO Criteria for Ships

These calculations are very useful during loading/unloading of a vessel, and also for planning vessel operations. It can be quickly deployed, and has been tested to give fairly accurate results.

How to use this App

Following Inputs are required before the user can evaluate a loading condition:
1. Principal Particulars of the Vessel
2. Hydrostatics of the Vessel (zero trim and zero heel)
3. Cross Curve Data of the Vessel
4. Downflooding points location
5. Tanks data
The user can create a new loading condition by giving it a unique name. The user has to input the Tank status, Fixed Weights and Deck Cargo for the loading condition
Once all inputs for a loading condition are provided by the user, the user can Solve the Loading condition. This will give the GZ curve, Trim and Heel status
To evaluate Stability as per IMO, user has two options: Stability for General Ships OR Stability for Barges. Upon selecting the correct option, the stability is evaluated

Assumptions/Limitations
The origin of the vertical axis is at the baseline of the vessel
Vessel is assumed to be symmetrical Port and Stbd
Only hydrostatics for zero heel and zero trim are utilised in calculations, so this spreadsheet is to be used only for low trim conditions (upto 5 deg)
The effect of free surface in tanks is calculated by considering the effect of free surface as a rise in the VCG of the vessel. While this may not represent the actual CG shift in tanks, it is a conservative approach in evaluation of the Righting Lever GZ
If detailed tank characteristics are not available, then the app calculates the FSM considering the tank as rectangular. While this may not be accurate for tanks which are not rectangular in shape, this gives conservative results

References
1. Principles of Naval Architecture, Vol 1, Edward V. Lewis
2. IMO Res A749(18), Code of Intact Stability for all types of Ships