Naval Architecture & Marine Engineering

Practical ship design calculators — fast checks, clean inputs, clear outputs.

Use these tools for hull coefficients, resistance estimates, propulsion power chain, stability basics & IMO indicators. Built to stay simple: no fluff, no hidden steps — just the numbers you need.

Hull Design Resistance Propulsion & Power Stability & Load IMO Navigation General Utilities

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Hull Design

Core hydrostatics & hull-form coefficients used in early-stage design and comparisons.

Block Coefficient (CB)
How “full” the underwater volume is.
Hull
Calculates CB from principal dimensions and displacement volume to quantify hull fullness.
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Midship Coefficient (CM)
Midship section “efficiency”.
Hull
Relates midship sectional area to B×T to evaluate section fullness.
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Prismatic Coefficient (CP)
Volume distribution along length.
Hull
Computes CP from displacement volume, L and midship area to support resistance trends.
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Waterplane Coefficient (CWP)
Waterplane “fullness”.
Hull
Finds CWP as AWP / (LWL × BWL), useful for stability & seakeeping intuition.
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Displacement
Mass/weight from volume & density.
Hull
Convert between displacement volume and mass using seawater/freshwater density.
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Waterplane Area (AWP)
Area at the waterline.
Hull
Estimate AWP for hydrostatics and stability calculations.
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Wetted Surface Area (WSA)
Skin friction driver.
Hull
Compute WSA to support frictional resistance estimates and scaling checks.
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LCB
Longitudinal centre of buoyancy.
Hull
Locate buoyancy centre along length to support trim/balance checks.
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LCF
Longitudinal centre of flotation.
Hull
Find the pivot point for small trim changes (important for trim/MCT logic).
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Bulbous Bow Volume & Area
Bulb geometry helpers.
Hull
Quick bulb metrics used in preliminary resistance discussions.
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Resistance

Estimate calm-water resistance with commonly used empirical/semi-empirical methods.

Holtrop–Mennen
Industry-standard resistance prediction.
Res
Predict resistance components using principal dimensions and form factors.
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Savitsky (Planing)
Planing hull resistance approach.
Res
Trim, lift and resistance estimates for planing craft.
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Telfer
Alternative resistance estimator.
Res
Empirical resistance estimation method for preliminary checks.
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Froude Estimator
Speed-based approximation.
Res
Quick resistance estimates using ITTC friction + residual assumptions.
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Model–Ship Correlation
Scaling & correlation tools.
Res
Convert model data to full-scale using standard correlation practices.
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Speed–Power Curve
Generate a curve from assumptions.
Res
Build a speed–power relationship using resistance estimates and efficiencies.
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Propulsion & Power

Translate resistance into effective, delivered and brake power — and evaluate key efficiency factors.

Propeller Slip
Advance vs actual travel.
Prop
Compute slip percentage from pitch, RPM and vessel speed.
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Propeller Efficiency (η₀)
Open-water efficiency.
Prop
Evaluate η₀ from thrust/power relationships (as per your calculator logic).
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Hull Efficiency (ηH)
Wake/thrust deduction effect.
Prop
Compute hull efficiency from wake fraction and thrust deduction.
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Relative Rotative Efficiency (ηR)
Behind-hull prop effects.
Prop
Compare behind-hull and open-water performance.
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Effective Power (PE)
Power to overcome resistance.
Power
Compute PE from resistance and speed.
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Delivered Power (PD)
Power at the shaft/prop.
Power
Convert effective power to delivered power using efficiency chain.
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Brake Power (PB)
Engine output requirement.
Power
Estimate PB from PD and drivetrain efficiencies.
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Stability & Load

Initial stability, trim, free surface effects, and longitudinal balance helpers.

GM
Initial transverse stability.
Stab
Evaluate GM and basic initial stability indicators.
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Trim
Longitudinal balance estimate.
Stab
Trim and longitudinal balance checks for loading changes.
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Free Surface Correction (FSC)
Slack tank stability loss.
Stab
Apply FSC to account for reduced GM due to free surface in tanks.
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MCT 1 cm
Moment to change trim.
Stab
Estimate MCT 1 cm for trim change calculations.
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GZ Curve Generator
Righting arm curve tools.
Stab
Generate and interpret a GZ curve based on stability inputs.
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Fuel & Machinery

Fuel consumption, engine efficiency, emissions, and operational performance tools.

Fuel Consumption
Engine fuel usage estimate.
Fuel
Estimate fuel consumption based on power, speed, and operating time.
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SFOC
Specific fuel efficiency.
Fuel
Analyze specific fuel oil consumption for marine engines.
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Fuel Cost
Voyage cost estimation.
Fuel
Calculate total fuel costs using consumption rates and fuel prices.
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CO₂ Emissions
Carbon output estimate.
Fuel
Estimate CO₂ emissions based on fuel type and consumption.
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EEOI
Operational efficiency index.
Fuel
Evaluate Energy Efficiency Operational Indicator for voyages.
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Speed Optimization
Fuel–speed tradeoff.
Fuel
Identify optimal operating speed for fuel and emission efficiency.
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IMO Calculators

Quick operational compliance helpers (EEDI/EEXI/CII and related utilities).

EEDI
Attained & required.
IMO
Calculate EEDI attained values and compare to required thresholds.
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EEXI
Attained & required.
IMO
Compute EEXI attained values and benchmark against required limits.
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CII Rating
Estimate annual rating.
IMO
Estimate CII and interpret likely rating band.
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Carbon Factor (CF)
Fuel CF lookup helper.
IMO
Find CF values used in emissions and IMO indicators.
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Capacity Helper (DWT/GT)
Capacity conversions.
IMO
Support capacity inputs required by multiple IMO formulas.
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Transport Work
tonne-mile helper.
IMO
Compute transport work to support efficiency indicators.
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EEXI Target Power Solver
Required power target.
IMO
Solve for target/limited power required to meet EEXI constraints.
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General Utilities

Quick helpers used across engineering workflows.

Unit Converter
Engineering unit conversions.
Gen
Convert common marine/engineering units quickly and safely.
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Percentage
Percent change and ratios.
Gen
Compute percent difference, increase/decrease, and ratio-based outputs.
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Date Calculator
Add/subtract dates.
Gen
Add or subtract durations and compute date differences.
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Linear Interpolation
Interpolate between points.
Gen
Quick linear interpolation for tables and curves.
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Reynolds Number
Flow regime quick check.
Gen
Compute Reynolds number for basic hydrodynamic reasoning.
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Density Converter
Common density units.
Gen
Convert density between kg/m³, g/cm³ and other common units.
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