Class 2 (2nd Engineer) SC&S 📅 Aug 2022

Exam Question

(a) Explain the use of KN curves. (6)

(b) The 1/2 breadths of the load waterplane of a ship 150 m long commencing from aft, are 0.3, 3.8, 6.0, 7.7, 8.3, 9.0, 8.4, 7.8, 6.9, 4.7 and O m respectively. Calculate:

(i) Area of waterplane

(ii) Distance of centroid from amidships

(iii) Second moment of area about a transverse axis through centroid.

Reference Answer

(a) KN curves are stability curves used in naval architecture. They are created by plotting the righting lever (KN) against the angle of heel (θ) for a given displacement and an assumed KG (height of the centre of gravity above the keel) of 0. The righting lever is the distance between the centre of buoyancy and the centre of gravity, measured along a vertical line through the centre of gravity.
The KN curve is then used to calculate the righting lever (GZ) for any other KG value using the following formula:
GZ = KN - KG * sin θ
Where:

Full answer on MeoMock — surveyor-grade reference answers for 7,000+ written exam questions.

View plans Browse library

← Browse more questions

Prepare on Android — MeoMock on Google Play