# Lab report using Maxsurf program Essay Example

Table of Content

Lab report using Maxsurf program

Introduction 2

Displacement, block and prismatic coefficients change 2

GZ values 2

Trimming moment 3

Trimming angle and forward and aft drafts 4

Conclusion 5

## Introduction

The stability of the vessel is critical whether there is change of vertical position of G on the position of the Metacentre will not alter the metacentric height. However, it changes laterally it will change leading to unstable equilibrium. When the vessel is inclined in a certain angle, the centre of buoyancy changes from the centreline as the centre of gravity does not change. This causes rotation of the vessel since the forces of both the buoyancy and gravity are the same but acting in different direction location. This balances both forcesleading to unstable equilibrium.

## Displacement, block and prismatic coefficients change

The following shows how the displacement, block and prismatic coefficients change with respect to the draft.

The observed changes are sensible as they are consisted with the parameters as expected.

## GZ values

Plotting GZ values with respect to the heel angle for two tested displacements (135000 and 145000 tonnes).

From the figure the negative GZ is experienced as , but we cannot think of all the mass as being concentrated at that point-that would give the wrong rotational inertia. It can be noted that from the above results that there is a huge difference between Theoretical metacentric Height (GM andExperimental metacentric Height (GM). The ships’ equilibrium point is not the point at which the forces of buoyancy forces and gravitational are equal. In equilibrium the vessel can tilt and the GM>0 or GM<0 is stretched downward a distance d from its centerline length so that the buoyancy causes movement.

Trimming moment When tanks 1 and 8 are partially filled with fresh water, it create a positive trimming moment since the weight is shifted forward, at the same time DdFWD will be positive and DdAFT will be negative. This is calculated as follows

## Trimming angle and forward and aft drafts

When the barge’s tank 1 and 2 are fully flooded with water, calculate the trimming angle and forward and aft drafts and compare your results with Maxsurf.

Change of trim forward = 39.3 cm

Trimming angle =

 Displacement t 0 0 0 0 0 0 0 0 0 0 Draft at FP m Draft at AP m Draft at LCF m Trim (+ve by stern) m 0 0 0 0 0 0 0 0 0 0 WL Length m Beam max extents on WL m Wetted Area m^2 Waterpl. Area m^2 Prismatic coeff. (Cp) Block coeff. (Cb) Max Sect. area coeff. (Cm) Waterpl. area coeff. (Cwp) LCB from zero pt. (+ve fwd) m LCF from zero pt. (+ve fwd) m Immersion (TPc) tonne/cm MTc tonne.m RM at 1deg = GMt.Disp.sin(1) tonne.m Max deck inclination deg 0 0 0 0 0 0 0 0 0 0 Trim angle (+ve by stern) deg 0 0 0 0 0 0 0 0 0 0

Trimming angle and forward and aft drafts are different from that produced by results with Maxsurf. This may be as results of errors of entry or calculation.

## Conclusion

The values of GZ for 135000 and 145000 have curves with similar trend. Meaning increasing weight does not affect GZ of vessel, but we cannot think of all the mass as being concentrated at that point-that would give the wrong rotational inertia. This is where buoyancy force works and this shows even when GZ is negative the vessel is stable due buoyancy. The difference between the two is the initial position at angle=0. If the position is at minimum then GM is either positive. The results generated by Maxsurf is more accurate. According to Maxsurf the trim is less than 1% while the excel has some of the figures of more than 1%