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Offshore Engineering Tools

Calculate.
Check. Ship.

Free engineering calculators and SACS workflow checklists for offshore structural engineers.

5
Calculators
3
Workflows
100%
Free
Calculators
⚓
DAF Calculator
Dynamic Amplification Factor for offshore lifts
DNV-ST-N001 (Dec 2023)
⚖️
CoG Shift & Tilt
Centre of gravity offset and tilt angle
DNV-ST-N001 (Dec 2023)
🏗️
Beam Unity Check
Combined axial + bending UC check
API RP 2A-WSD 22nd Ed. / ISO 19902:2007
〰️
Miner's Rule
Cumulative fatigue damage calculation
DNV-RP-C203
🚢
Ship Impact Energy
Vessel collision kinetic energy check
NORSOK N-004
🌊
Wave Theory Selector
Airy / Stokes 5th / Stream Function
API RP 2A
SACS Workflow Checklists
✅
General SACS Checklist
Pre/post-processing checks for any SACS analysis
Modeling · Pre · Post
📋
Fatigue (Spectral)
Step-by-step spectral fatigue workflow in SACS
14 steps · DNV-RP-C203
🏋️
Lifting Analysis
SACS lifting model setup to output review
10 steps · DNV-ST-N001 (Dec 2023)
🪝
PSI / Foundation
Pile-Soil Interaction workflow in SACS
10 steps · API RP 2A
TOE Academy · SACS Masterclass

Master offshore analysis end-to-end

These tools cover the quick checks. The Masterclass teaches you to own the full analysis — PSI, Fatigue, Lifting, Loadout, Pushover and more.

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Calculators
Free engineering calculators — results shown with code references
Dynamic Amplification Factor (DAF)
Offshore lift DAF per DNV-ST-N001 (Dec 2023) Table 4-4
DNV-ST-N001 (Dec 2023)
Free ▼
W W·g DAF × W·g Hs Crane Type Fixed / HLV Hs (Sea State) → DAF value Design Sling Load = W × DAF × g per DNV-ST-N001 (Dec 2023) T4-4
Dynamic Amplification Factor—
Design Sling Load—
Static Hook Load—
Governing Condition—
CoG Shift & Tilt Angle
Centre of gravity offset and maximum tilt angle
DNV-ST-N001 (Dec 2023) §4.3
Free ▼
L B CoG nominal CoG actual Δx Δy Hook h θ tilt Tolerance Class A: ±1.0% · B: ±1.5% · C: ±3.0% CoG Offset Δx = f × L Δy = f × B Tilt Angle θ = arctan(√(Δx²+Δy²) / h)
CoG Offset ±X (m)—
CoG Offset ±Y (m)—
Maximum Tilt Angle (°)—
Skew Load Effect—
Beam Unity Check
Tubular member combined axial + bending interaction
API RP 2A-WSD 22nd Ed. §H.3
Free ▼
OD WT fa fa M KL (effective length) fa/Fa > 0.15 → Eq. H1-1 fa/Fa + Cm·fb/((1-fa/Fe)·Fb) ≤ 1.0 fa/Fa ≤ 0.15 → Eq. H1-2 fa/(0.6Fy) + fb/Fb ≤ 1.0 Allowable axial Fa Euler buckling (λ vs Cc) API RP 2A-WSD 22nd Ed. §H.3
Cross-section Area A (cm²)—
Axial Stress fa (MPa)—
Bending Stress fb (MPa)—
Allowable Axial Fa (MPa)—
Allowable Bending Fb (MPa)—
Unity Check (UC)—
Status—
Utilization ratio
Miner's Rule — Fatigue Damage
Cumulative damage sum with S-N curve selection
DNV-RP-C203 (Oct 2024) §2
Free ▼
log N (cycles) log Δσ S-N curve slope m=3 Δσ₁ Δσ₂ n₁ n₂ N₁ Miner's Rule D = Σ (nᵢ / Nᵢ) N from S-N curve N = 10^logC / (SCF·Δσ)^m Fatigue life L = T_design / D (years) Pass if L ≥ DFF × T_design DNV-RP-C203 (Oct 2024) §2
Stress Ranges (enter up to 4 blocks)
Cumulative Damage ΣD—
Fatigue Life (years)—
Required Life (DFF × Design)—
Status—
Damage ratio D/1.0
Ship Impact Energy
Vessel collision kinetic energy and equivalent static force
NORSOK N-004 Rev.3 (2013) §A.3
Free ▼
sea surface jacket Δ tonnes v m/s Ek = ½·Δ·(1+Ca)·v² Ca = 0.05 bow | 0.40 beam Beam impact Ca = 0.40 Bow impact Ca = 0.05 NORSOK N-004 Rev.3 (2013) §A.3
Added Mass Coefficient Ca—
Effective Mass m_eff (tonnes)—
Kinetic Energy Ek (MJ)—
Minimum Absorbed Energy (MJ)—
Equivalent Static Force (MN)—
Wave Theory Selector
Recommends Airy / Stokes 5th / Stream Function based on Le Méhauté
API RP 2A-WSD 22nd Ed. / DNV-RP-C205 (Sep 2021)
Free ▼
H / gT²—
d / gT²—
Relative Depth (d/L)—
Recommended Theory—
TOE Academy

Learn to use these in real SACS models

The SACS Masterclass shows exactly how these values feed into your analysis — wave loads, DAF in lifting models, fatigue checks in spectral analysis.

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SACS Workflow Checklists
Step-by-step checklists with SACS tips and common mistakes flagged
Fatigue Analysis — Spectral Method
SACS + DNV-RP-C203 (Oct 2024)
0 / 14
START: Fatigue Analysis 01. Set up global SACS model Member connectivity · fixity codes · end releases 02. Run PSI Foundation Analysis Required before fatigue — pile super-element needed 03. Linearize Foundation (PSI) Generate pile super-element at mudline 04. Set up DYNPAC input Mass matrix · freq range · added mass 05. Run Modal Analysis (DYNPAC) Extract mode shapes · verify mass participation >90% fn near wave frequency? Yes ⚠ review DAF No 06. Define scatter diagram Hs-Tz matrix · heading distribution · probabilities 07. Assign S-N curves & SCFs DNV-RP-C203 (Oct 2024) · class per joint · Efthymiou SCF 08. Set up GNTRF (Wave Response) 8+ directions · 20+ frequencies · Stokes 5th 09. Run Wave Response Analysis Compute transfer functions (RAOs) per freq/dir 10. Run Spectral Fatigue Analysis Integrate force spectra · compute ΣD per joint Joint fatigue life < DFF×T? Yes redesign Pass Report & Document Step 14 complete
Lifting Analysis Workflow
SACS + DNV-ST-N001 (Dec 2023)
0 / 10
START: Lifting Analysis 01. Review lifting arrangement Padeye locations · rigging geometry · CoG from SWR 02. Calculate design lift weight Apply contingency (5–10%) + rigging weight 03. Compute DAF + sling loads DAF per DNV-ST-N001 (Dec 2023) T4-4 · CoG tolerance · skew 04. Set up SACS lifting model Padeye nodes · sling forces with angle · DAF applied 05. Define load combinations ULS = 1.35D + 1.35L + 1.0 DAF · per DNV-ST-N001 §5 06. Run SACS analysis → UC ratios Check all member UCs · deflections at lift points Any UC > limit? Yes revise Pass 07. Detailed padeye checks Shear · bearing · tear-out · weld · ±3° out-of-plane 08. Rigging hardware check Shackle WLL · sling MBL/SF=4 · hook capacity Report → TPV Approval Plan 3 weeks for TPV review
PSI / Foundation Workflow
SACS + API RP 2A
0 / 10
START: PSI / Foundation 01. Obtain soil investigation report Su (clay) / φ (sand) · unit weights · to pile tip depth 02. Define pile geometry in SACS OD · WT · penetration · nodes per soil layer 03. Generate P-Y curves (lateral) Matlock (soft clay) · Reese (sand) · cyclic for storm 04. Generate T-Z curves (axial skin) α-method (clay) · β-method (sand) · API RP 2A-WSD 05. Generate Q-Z curve (end bearing) Tip resistance · z at full mobilization ≈ 10% OD 06. Run PSI (storm + operating) Pile head displacements · reactions · pile UC ratios Pile capacity adequate? No revise pile OK 07. Linearize foundation for fatigue 6×6 stiffness matrix per pile at mean dead load 08. Generate pile super-element Export for global fatigue + dynamic analysis Document PSI Results Capacity table · FOS · plots
TOE Academy · SACS Masterclass

Go beyond the checklist

These checklists are the map. The Masterclass gives you the full terrain — model files, live walkthroughs, error troubleshooting, and output interpretation.

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SACS Checklists
Quality checklists for SACS analysis — tick off as you go
General SACS Analysis Checklist
Applies to all SACS analysis types
0 / 28
Fatigue Analysis — Spectral Method
SACS + DNV-RP-C203 (Oct 2024)
0 / 14
Lifting Analysis Workflow
SACS + DNV-ST-N001 (Dec 2023)
0 / 10
PSI / Foundation Workflow
SACS + API RP 2A-WSD 22nd Ed.
0 / 10
TOE Academy · SACS Masterclass

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The Masterclass walks through every checklist item with live SACS models, real input files, and output interpretation — so you never have to guess again.

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