Marine Deck Machinery Sizing Calculator
Free engineering tool for anchor windlass & mooring winch specification
Based on IACS UR A3 & Classification Society Standards
Anchor Windlass Sizing
Calculate continuous duty pull, brake capacity, and motor power per IACS UR A3.
Chain Stopper Fitted
Continuous Duty Pull (Breaking test load per IACS UR A3):
K = 37.5 (U1) | 42.5 (U2) | 47.5 (U3)
Result Z in N; divide by 1000 for kN
Overload Pull:
Brake Holding Capacity:
Kb values:
U1: 4.41 (with stopper) / 7.85 (without)
U2: 6.18 (with stopper) / 11.0 (without)
U3: 8.83 (with stopper) / 15.7 (without)
Motor Power:
where F = continuous pull (N), V = speed (m/min)
Chain Wheel Dimensions (5-pocket stud link):
OD ≈ PCD + 2.4 × dc
Winch Drum Sizing
Calculate drum barrel diameter, width, flange diameter, and layer count for mooring winch drums.
Minimum Drum Barrel Diameter:
6×19: ratio = 25 | 6×37: ratio = 18 | HMPE: ratio = 10
Rope Capacity (rope length on drum):
Required Drum Width (rearranged):
Flange Diameter:
Plus clearance: top layer ≥ 3 × dr below flange
Wraps per Layer:
Bow vs. Stern Configuration
Typical deck machinery arrangement comparison.
Bow (Forecastle) Arrangement
Gearbox
Wheel
Drum
Drum
Bow windlass includes chain wheel(s) for anchor chain handling, plus mooring drum(s). Brake band on chain wheel provides holding force.
Stern (Aft) Arrangement
Gearbox
Drum
Drum
Stern mooring winch typically omits chain wheel. Designed for mooring lines only (wire rope or synthetic). May include warping head.
Deck Machinery Layout Arrangements
Three common arrangement options for vessel deck machinery.
Plan A: Independent
Separate anchor windlass and mooring winch. Each unit independently powered. Offers maximum flexibility but requires more deck space.
Plan B: Combined
Windlass-mooring winch combination. Single drive unit handles both anchoring and mooring. Most space-efficient and cost-effective solution.
Plan C: Triple-Drum
Integrated triple-drum configuration for larger vessels. Provides anchor handling plus dual mooring capability on a single shaft line.
Watch: Winch drum sizing: prepare the inputs before calculating
Prepare rope length, drum geometry, layers and retained wraps before using the drum-sizing section. Calculator results are preliminary and require design confirmation.
Illustrative procurement and selection guide; not product footage or performance test evidence. Confirm the final specification for your application.
Send rope diameter and length, barrel and flange dimensions, working width and required duty. Request a quotation: sales@hiqool.com
Need a Quotation for Your Project?
Our engineers can help you specify the right deck machinery for your vessel — from preliminary sizing to classification-approved drawings.