• Scow bow with maximum beam at Station 2 (35% LOA from bow)
• Fine stern sections for reduced drag in displacement mode
• Flat bottom panels forward transitioning to V-sections aft
SHEET: 2 OF 7
Sheet 3: Foil System Detail
Component
Material
Dimensions
Main Foil Strut
Carbon fiber/epoxy, 4 layers
1050mm span × 100mm chord
Main Foil Wings
Carbon/foam sandwich
950mm span × 280mm root chord
Rudder Stock
40mm carbon tube
900mm span
FOIL SYSTEM NOTES:
• NACA 63-412 section modified for low cavitation
• Flap deflection range: -5° to +15° controlled by wand
• Foil surfaces polished to 1200 grit minimum
SHEET: 3 OF 7
Sheet 4: Deck Layout
DECK LAYOUT NOTES:
• Wing decks extend 400mm each side from hull centerline
• All control lines led to cockpit within easy reach
• Mainsheet system: 4:1 or 6:1 purchase with ratchet block
SHEET: 4 OF 7
Sheet 5: Construction Sections
CONSTRUCTION NOTES:
• Vacuum bag to minimum 25" Hg during cure
• Epoxy resin: West System 105/206 or equivalent
• High-stress areas use carbon honeycomb core
SHEET: 5 OF 7
Sheet 6: Rigging Diagram
RIGGING NOTES:
• All control lines use Dyneema for minimum stretch
• Mainsheet: 6mm, 4:1 or 6:1 purchase
• Vang: 16:1 cascade for mast bend control
SHEET: 6 OF 7
Sheet 7: Assembly Details
CRITICAL ASSEMBLY POINTS:
• All structural bonds must cure minimum 24 hours
• Foil surfaces must be perfectly smooth
• Wand linkage requires proper calibration
• Check all fasteners for proper torque
SHEET: 7 OF 7
System Overview: Automatic Stabilization
DESIGN OBJECTIVE:
Replace manual hiking with automatic active ballast. Movable weights on retractable arms controlled by gyroscopic sensors enable senior sailors to enjoy foiling without physical strain.
Component
Specification
Function
Ballast Weights
2× 15kg lead
Righting moment
Extension Arms
Carbon tube, 1500mm max
Position weights
Servo Motors
2× linear actuators, 12V
Extend/retract arms
Gyro Sensor
6-axis IMU
Measure heel angle
Battery
12V 20Ah LiFePO4
4-6 hours operation
BENEFITS FOR SENIOR SAILORS:
• No physical hiking required
• Automatic heel compensation
• Reduced physical strain
• Same foiling performance
SHEET: 1 OF 5
Ballast Arm Mechanism
TELESCOPING ARM SYSTEM:
Carbon fiber telescoping arms with linear actuators provide smooth, automatic weight positioning.
Electronics & Control
CONTROL SYSTEM:
Arduino/Raspberry Pi based ECU with PID control algorithm for smooth, responsive stabilization.
Hull Integration
MOUNTING:
Arm housings bonded to hull interior with reinforcement. All electronics waterproofed to IP67.
Operation Guide
OPERATING MODES:
AUTO (default), MANUAL (override), CALIBRATION, and EMERGENCY STOP modes available.
STANDARD vs SENIOR MOTH COMPARISON
Standard International Moth
Design: Traditional foiling dinghy
Total Weight: 70 kg (30kg hull + 40kg rigging/sailor)
Stabilization: Manual hiking by sailor
Righting Moment: 70-100 kg sailor @ 300-500mm
Physical Demands: High - athletic hiking
Target: Competitive sailors, athletes
Senior Moth Active Ballast
Design: Automated stabilization system
Total Weight: 83 kg (30kg hull + 41kg ballast + 12kg rigging)
Stabilization: Automatic ballast arms
Righting Moment: 2×15kg @ 1500mm extension
Physical Demands: Low - sit-and-sail
Target: Senior sailors, adaptive sailing
Key Differences
Aspect
Standard Moth
Senior Moth
Weight
70 kg total
83 kg total (+18%)
Response Time
1-2 seconds (human)
<1 second (automatic)
Heel Control
±15-20° typical
±5° maximum
Accessibility
Requires fitness
No hiking needed
Complexity
Moderate
High (electronics)
Maintenance
Standard rigging
+ Battery & electronics
Cost
Baseline
+$3000-5000 (system)
PERFORMANCE COMPARISON:
Speed: Both capable of 25-30+ knots foiling Stability: Senior Moth more stable (automated response) Learning Curve: Senior Moth easier (no hiking skill needed) Physical Demand: Senior Moth dramatically lower Session Length: Senior Moth enables longer sessions without fatigue