2-1 A small boat weighing 40 LT has a submerged volume of 875 ft3 when traveling at 20 kts in

seawater. (ρ = 1.99 lb·s2ft4 ; 1 LT = 2240 lb)

(a) Calculate the magnitude of the hydrostatic support being experienced by boat.

FBuoyancy = ρgVsub = 1.99 lb·s2ft4 · 32.2 ft

s2 · 875 ft3 = 56,068 lb · 1 LT2,240 lb = 25 LT

(b) What other type of support is the boat experiencing?

In addition to hydrostatic support, this boat is experiencing hydrodynamic support/lift.

(c) Calculate the magnitude of this other type of support.

FHydrodynamic = Wboat − FBuoyancy = 40 LT − 25 LT = 15 LT

(d) What will happen to the submerged volume of the boat if it slows to 5 knots? Explain your

answer.

Hydrodynamic lift is proportional to V 2boat. As the boat slows, the reduction in hydrodynamic

support will cause the boat weight to exceed the total lift so the boat will sink down (draft, T ,

will increase). As T increases, Vsub increases so Fbuoyancy increases until a new equilibrium is

reached at a new, deeper, draft.

12. hi

2-4 Sketch a profile of a ship and show the following:

(a) Forward Perpendicular

(b) After Perpendicular

(c) Sections, assuming the ship has stations numbered 0 through 10.

(d) Length Between Perpendiculars

(e) Length Overall

(f) Design Waterline

(g) Amidships

13. hi

2-5 Sketch a section of a ship and show the following:

(a) Keel

(b) Depth

(c) Draft

(d) Beam

(e) Freeboard

14. hi

+x

+y

+zC

. (translation)_H

eave_

A.(translation)

_Surge_

B. (translation)

_Sway_

E. (rotation)_Trim

_/_Pitch_

D. (rotation)

_Roll_/_List_/_H

eel_

F. (rotation)_Yaw

_

G. V

iewed from

bow_B

ody_ Plan

H. V

iewed from

side_Sheer_ Plan

I. View

ed from top

_Half_ -_B

readth_ Plan

J. _Section_ Line

K. _B

uttock_ Line

L. _Water_ Line

M. H

orizontal ref plane forvertical m

easurements

_Baseline_

N. Forw

ard ref plane forlongitudinal m

easurements

_Forward_ _Perpendicular_

O. A

ft ref plane forlongitudinal m

easurements

_Aft_ _Perpendicular_

P. Middle ref plane for

longitudinal measurem

ents_M

idships_

Q. Longitudinal ref plane for

transverse measurem

ents_C

enterline_

R. D

istance between “N

.” & “O

.”_Lpp_=_Length_ _B

etween_ _Perpendicular_

S. Width of the ship

_Beam

_

EN400 Chapter 2 Prob 6

2-7 For this question, use a full sheet of graph paper for each drawing. Choose a scale that gives the

best representation of the ship’s lines. Use the FFG-7 Table of Offsets given on the following page for

your drawings.

(a) For stations 0-10 draw a Body Plan for the ship up to the main deck. Omit stations 2.5 and 7.5.

(b) Draw a half-breadth plan showing the 4 ft, 12 ft, 24 ft waterlines, and the deck edge.

(c) Draw the sheer profile of the ship.

Prob 8

Prob 9

Prob 9

Prob 10

Prob 11

Prob 12

Prob 13

Prob 14

Prob 15, 1615)

16)

Prob 17, 1817)

18)

Prob 19, 2019)

20)