A ship of 7800 tonnes displacement has a mean draft of 6.8m and is to be loaded to a mean draft of 7 metres. GM 0.7m and TPC 20 tonnes. The ship is at present listed 4 degrees to starboard. How much more cargo can be shipped in the port and starboard tween deck, centres of gravity 6m and 5m, respectively, from the centreline, for the ship to complete loading and finish upright.

A ship of 7800 tonnes displacement has a mean draft of 6.8m and is to be loaded to a mean draft of 7 metres. GM 0.7m and TPC 20 tonnes. The ship is at present listed 4 degrees to starboard. How much more cargo can be shipped in the port and starboard tween deck, centres of gravity 6m and 5m, respectively, from the centreline, for the ship to complete loading and finish upright.

Reference: Ship Stability for Masters & Mates (6^th edition), Exercise – 14.3

 

Solution:

Total weight to be loaded = ∆d * TPC

                                           = (7-6.8) * 20*100

                                           = 400 tons

Tanθ = GG₁/GM

=> GG₁ = tanθ * GM

=> GG₁ = tan4⁰ * 0.7

=> GG₁ = 0.0489 m

Weight (ton)	TCG (m)	Moment (ton-m)
7800	0.0489 (s)	381.8
W	6 (p)	6w
400-w	5(s)	2000-5w

 

Moment in port = Moment in starboard

=> 6w = 381.8 + 2000 – 5w

=> w = 216.52 tons

216.52 tons of cargo can be shipped in the port.

400-216.52 = 183.48 tons of cargo can be shipped in the starboard.