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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
Arjun Viswanathan
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Arjun Viswanathan
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Calculators
🚢
Ship Impact Energy
Vessel collision kinetic energy and equivalent static force
NORSOK N-004 Rev.3 (2013)
🌊
Wave Theory Selector
Airy / Stokes 5th / Stream Function per Le Méhauté
API RP 2A / DNV-RP-C205
〽️
Morison Wave Load
Drag + inertia force on a cylindrical member
API RP 2A-WSD 22nd Ed. §2.3
🔗
Sling Load & Tension
Sling tensions from rigging geometry and lift weight
DNV-ST-N001 (Dec 2023)
🔩
Tubular Joint UC
Punching shear check for K, T/Y and X joints
API RP 2A-WSD 22nd Ed. §4.3
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
15 steps · DNV-RP-C203
🏋️
Lifting Analysis
SACS lifting model setup to output review
11 steps · DNV-ST-N001 (Dec 2023)
🪝
PSI / Foundation
Pile-Soil Interaction workflow in SACS
11 steps · API RP 2A-WSD 22nd Ed.
TOE Academy · SACS Masterclass

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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
Ship Impact Energy
Vessel collision kinetic energy and equivalent static force
NORSOK N-004 Rev.3 (2013) §A.3
SI · ULS · WSD
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)
SI · Kinematics only
Free ▼
H / gT²—
d / gT²—
Relative Depth (d/L)—
Recommended Theory—
Morison Wave Load
Drag + inertia force on a cylindrical member (Morison equation)
API RP 2A-WSD 22nd Ed. §2.3 / DNV-RP-C205 (Sep 2021)
SI · Characteristic force · WSD
Free ▼
u (wave velocity) D F Morison equation (total per member) F = FD + FI Drag force FD = ½·ρ·Cd·D·u|u|·L Inertia force FI = ρ·Cm·(π/4)·D²·u̇·L Cd ≈ 0.65 clean / 1.05 w/ marine growth Cm = 2.0 default · API RP 2A-WSD §2.3
Drag Force FD (kN)—
Inertia Force FI (kN)—
Total Force F (kN)—
Force per Unit Length (kN/m)—
Drag / Inertia Split—
Sling Load & Tension
Sling tensions from rigging geometry for 2- and 4-point lifts
DNV-ST-N001 (Dec 2023) §4.3
SI · Design tension · WSD
Free ▼
Hook θ W (tonnes) h 2r Sling angle from vertical θ = arctan(r / h) Nominal sling tension (n legs) T = (W·DAF·g) / (n·cosθ) Design tension with skew φ T_des = T × (1 + φ) Min MBL = T_des × SF (SF=4) DNV-ST-N001 (Dec 2023) §4.3
Sling Angle θ from Vertical (°)—
Nominal Sling Tension T (kN)—
Design Tension with Skew (kN)—
Sling Length L (m)—
Min Required MBL (kN)—
Tubular Joint Punching Shear (UC)
Joint capacity check for K, T/Y and X joints
API RP 2A-WSD 22nd Ed. §4.3
SI · WSD · Punching shear only
Free ▼
CHORD D / T brace (d) θ punching shear zone g Punching shear stress vp = (P·sinθ) / (π·D·T) Allowable punching shear vpa = Qq·Qf·Fy / (0.6·γ·√3) UC = vp / vpa ≤ 1.0 γ = D/(2T) · β = d/D Qq = f(joint type, β, γ, sinθ) API RP 2A-WSD 22nd Ed. §4.3
γ = D/(2T) — Chord Slenderness—
β = d/D — Diameter Ratio—
Qq (Geometry Factor)—
Qf (Chord Load Factor)—
Punching Shear vp (MPa)—
Allowable vpa (MPa)—
Unity Check (UC)—
Status—
Utilization ratio
TOE Academy

Learn to use these in real SACS models

The SACS Masterclass shows exactly how these values feed into your analysis — Morison wave loads, sling tensions in lifting models, joint checks in jacket 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 / 15
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 ⚠ check damping / 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 SCF / DFF / WT / re-profile Pass Report & Document All workflow stages complete
Lifting Analysis Workflow
SACS + DNV-ST-N001 (Dec 2023)
0 / 11
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 F_ULS = γf × DAF × W · 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-WSD 22nd Ed.
0 / 11
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 ≈ 5% 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 / 15
Lifting Analysis Workflow
SACS + DNV-ST-N001 (Dec 2023)
0 / 11
PSI / Foundation Workflow
SACS + API RP 2A-WSD 22nd Ed.
0 / 11
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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