Question: why tpc varies with different draughts?
Answer: (FRESH WATER ALLOWANCE) It is the difference in draught or change in the draught (▲ D = D1 – D2), when the ship is going from FW (Fresh water) to SW (Sea Water) i.e. in this case ship must “Rise”. Due to change in density or change in magnitude in Buoyancy Force or thrust force.