Hydrostatics

Patrol Craft 40 — calculated by Simpson's Rule at T = 2m draft

Hydrostatic Results

Parameter	Value	Unit	Description
Waterplane Area (Aw)	264.83	m²	Area of the waterplane at design draft
Displaced Volume (∇)	449.66	m³	Volume of hull below design waterline
Displacement (Δ)	460.9	t	Salt water 1.025 t/m³
Displacement (Long Tons)	453.6	LT	1 LT = 1.01605 t — used in Indian Navy / IRS
TPC	2.714	t/cm	Tonnes Per Centimetre immersion — Aw × 1.025 / 100
FWA	42.4	mm	Fresh Water Allowance — Δ / (4 × TPC)
LCB from AP	19.53	m	Longitudinal Centre of Buoyancy
LCF from AP	19.42	m	Longitudinal Centre of Flotation
KB	1.10	m	Height of Centre of Buoyancy above keel
BM	2.27	m	Metacentric radius
KM	3.37	m	Height of Metacentre above keel
Block Coeff (Cb)	0.781		∇ / (L × B × T)
Waterplane Coeff (Cw)	0.920		Aw / (L × B)
Midship Coeff (Cm)	0.941		Am / (B × T)
Prismatic Coeff (Cp)	0.829		∇ / (Am × L)

Vertical Stability Stack

KM

3.37m

Height of Metacentre

BM

2.27m

Metacentric radius (offset)

KB

1.10m

Height of Centre of Buoyancy

K

0.00m

Keel (baseline)

Block Coeff Cb

0.781

0.45–0.85 typical

Waterplane Cw

0.920

0.60–0.95 typical

Midship Cm

0.941

0.80–0.99 typical

Prismatic Cp

0.829

0.55–0.80 typical

Sectional Areas by Station

Station	Section Area (m²)	Visual
0 (AP)	6.70
1	9.62
2	11.62
3	12.73
4	13.28
5	13.55
6	13.42
7	12.78
8	11.41
9	8.38
10 (FP)	2.80

All calculations use Simpson's 1/3 Rule for numerical integration of the offset data. Salt water density = 1.025 t/m³. Results are approximate — accuracy depends on the number of stations and waterlines in your offset table.