📋 Core Assumptions & Constraints
- Propulsion (Mutually Exclusive):
- Kite: 3.0 mph (2.6 kts) only when Course is within 30° of True Downwind vector.
- Solar Peak: 2.0 mph for 6 hrs (Sun high).
- Solar/Battery: 1.0 mph for 18 hrs.
- Solar 24hr Avg: 1.25 mph (1.09 kts) constant, regardless of wind angle.
- Kite Geometry: Trade Winds blow West (NE Trades → SW; SE Trades → NW). Direct West course is 45° off Downwind. Kite requires Zig-Zag (Tacking) at ±30° off Downwind. Resulting VMG West = 3.0 * cos(30°) = 2.6 mph (2.26 kts).
- Route Policy: Westabout via Tropics (Panama & Suez Canals assumed passable). Strict avoidance of Roaring 40s / Furious 50s (Lat < 35°). Target Significant Wave Height < 15 ft.
- Currents: Equatorial Counter/Current (+0.5–1.0 kts West); Agulhas Current (+2.5–3.5 kts SW); Brazil Current (+1.0 kts SW).
- Weather Routing: Starlink + Forecasts used for Eddy hopping & Hurricane avoidance. No provisioning/repair stops counted.
- Hurricane Seasons: NH (Jun–Nov, Peak Aug–Oct) | SH (Nov–Apr, Peak Jan–Mar).
⚙️ Propulsion Logic: "The Zig-Zag Imperative"
Because Trade Winds arrive at ~45° to a Rhumb-line West course, the Kite cannot fly on a direct 270° heading (Limit: 30° off Downwind).
| Hemisphere | Wind From | Downwind To | Allowed Kite Course | VMG West (3 mph) | Strategy |
|---|---|---|---|---|---|
| Northern (10°N–25°N) | NE (045°) | SW (225°) | 195° – 255° (WSW) | 2.6 mph | Zig-Zag WSW / WNW |
| Southern (10°S–25°S) | SE (135°) | NW (315°) | 285° – 345° (WNW) | 2.6 mph | Zig-Zag WNW / WSW |
| Doldrums / Horse Latitudes | Light / Variable | N/A | N/A | 1.25 mph (Solar) | Solar Only |
Effective Kite Speed West (VMG) = 2.26 kts. + Current (avg 0.7 kts) ≈ 3.0 kts West. Solar Avg = 1.09 kts.
🗺️ Optimized Route: "The Tropical Express" (Westabout)
START: Fort Lauderdale, FL (26°N)
│
▼ LEG 1: Caribbean → Panama Canal (1,100 nm)
NE Trades (WSW Zig-Zag) + Current → ~3.1 kts VMG
│
▼ PANAMA CANAL TRANSIT (1 Day)
│
▼ LEG 2A: Panama → Galápagos (900 nm)
Light/Variable Winds (Doldrums/Transition) → Solar Dominant ~1.5 kts
│
▼ LEG 2B: Galápagos → Marquesas (3,000 nm)
SE Trades (WNW Zig-Zag) + SEC Current → ~3.4 kts VMG
│
▼ LEG 3: Marquesas → Fiji → Solomons → Indonesia (4,500 nm)
Steady SE Trades (WNW Zig-Zag) + SEC → ~3.3 kts VMG
│
▼ LEG 4: Indonesia (Internal Waters) → Mauritius (3,500 nm)
SE Trades (WNW Zig-Zag) + SEC → ~3.1 kts VMG
│
▼ LEG 5: Mauritius → Agulhas Current → South Atlantic (2,500 nm) ⚠ CRITICAL LEG
Ride Agulhas Current SW (3.0 kts) + Solar (1.1 kts) = ~4.1 kts
*Kite UNUSABLE (Wind angle > 30°). WAIT for "Agulhas Window" (High Pressure, <15ft seas).
│
▼ LEG 6: South Atlantic → Brazil → Caribbean (4,500 nm)
SE Trades (WNW Zig-Zag) + Brazil Current → ~3.3 kts VMG
│
▼ LEG 7: Caribbean → Fort Lauderdale (1,000 nm)
NE Trades (WSW Zig-Zag) → ~3.1 kts VMG
│
▼ FINISH
📊 Leg-by-Leg Time Estimate
| Leg | Route Segment | Distance (nm) | Primary Propulsion | Est. Speed (kts VMG) | Transit Time | Notes / Risks |
|---|---|---|---|---|---|---|
| 1 | Fort Lauderdale → Panama Canal | 1,100 | Kite Zig-Zag (NE Trades) + Current | 3.1 | 15 Days | Reliable Trades. Canal transit +1 Day. |
| 2A | Panama → Galápagos | 900 | Solar / Light Air Kite | 1.5 | 25 Days | Doldrums/ITCZ crossing. Unpredictable winds. |
| 2B | Galápagos → Marquesas | 3,000 | Kite Zig-Zag (SE Trades) + SEC | 3.4 | 37 Days | Classic "Milk Run". Best Kite performance. |
| 3 | Marquesas → Fiji → Indonesia | 4,500 | Kite Zig-Zag (SE Trades) + SEC | 3.3 | 57 Days | Longest stretch. Steady Trades. Cyclone risk if late (SH Summer). |
| 4 | Indonesia Archipelago Transit | 500 | Solar / Tidal Currents | 1.8 | 12 Days | Narrow straits, adverse tidal currents, light winds. |
| 5 | Indonesia → Mauritius | 3,500 | Kite Zig-Zag (SE Trades) + SEC | 3.1 | 47 Days | Steady Trades. Mauritius arrival ~Late Oct. |
| 6 | Mauritius → Agulhas → Cape Town | 1,800 | Agulhas Current (3.0 kts) + Solar | 4.1 | 18 Days | HIGH RISK. Kite OFF. Must catch "Agulhas Window" (High Pressure Ridge). +14 Days Wait Time budgeted. |
| 7 | Cape Town → St. Helena → Brazil | 2,500 | Kite Zig-Zag (SE Trades) + Brazil Current | 3.3 | 32 Days | SE Trades strong. Brazil Current assists last 1000nm. |
| 8 | Brazil → Caribbean (Via Eq Current) | 2,000 | Kite Zig-Zag (SE/NE Trades) + NBC | 3.2 | 26 Days | Cross Equator (Doldrums slow). NBC Retroflection eddies used. |
| 9 | Caribbean → Fort Lauderdale | 1,000 | Kite Zig-Zag (NE Trades) | 3.1 | 13 Days | Home stretch. |
| TOTAL SAILING TIME | 282 Days | |||||
| CANAL TRANSITS (Panama + Suez*) | 2 Days | *Suez avoided; Panama only | ||||
| WEATHER / AGULHAS WAIT TIME | 35 Days | Agulhas Window (14d) + ITCZ Delays (10d) + Contingency (11d) | ||||
| GRAND TOTAL ESTIMATE | 319 – 335 Days | |||||
*Note: Route uses Panama Canal only. Suez Canal route (Red Sea) requires beating NW winds (Kite useless) and adds distance. Panama is faster for Westabout.
📅 Seasonal Timing Strategy (The "May Start" Window)
To satisfy No 40s/50s, Waves < 15ft, and Hurricane Avoidance simultaneously, the departure date is critical.
| Period | Location / Leg | Seasonal Context | Risk Assessment |
|---|---|---|---|
| May 1 – Jun 15 | Legs 1, 2A (Atlantic / Panama) | NH Pre-Hurricane / SH Winter | ✅ SAFE. NH Cane season starts Jun 1. We clear Caribbean early. |
| Jun 15 – Oct 15 | Legs 2B, 3, 4, 5 (Pacific / Indian Ocean) | SH Winter (Dry Season) | ✅ OPTIMAL. Steady SE Trades. **Zero Cyclones** in South Pac/Indian Ocean. Best Kite performance. |
| Oct 20 – Nov 20 | Leg 5 Arrival Mauritius / Prep Agulhas | SH Spring / Cyclone Season Start (Nov 1) | ⚠️ CAUTION. Cyclones rare in Nov but possible. High pressure systems frequent = Good Agulhas windows. |
| Nov 20 – Dec 20 | Leg 6 (Agulhas Crossing → S. Atlantic) | SH Late Spring | ⚠️ CRITICAL WINDOW. Wait for 3-day High Pressure forecast. Agulhas Current 3kts + Solar = Fast transit. Waves <15ft likely under High. |
| Dec 20 – Mar 1 | Legs 7, 8 (S. Atlantic → Brazil → Caribbean) | SH Summer / NH Winter | ✅ SAFE. No Hurricanes in S. Atlantic. NE Trades reliable in N. Hemisphere Winter. |
| Mar 1 – Apr 15 | Leg 9 (Caribbean → Home) | NH Spring | ✅ SAFE. Well before NH Hurricane Season (Jun 1). |
⚠️ Top 3 Mission Risks
- The Agulhas "Gate" (Leg 6): The only place waves routinely exceed 15ft below 35°S. A "Natal Pulse" or Cold Front creates 30ft+ steep waves opposing 3kt current. Mitigation: 2-week buffer in Mauritius/Rodrigues for Starlink forecast window. If no window for 3 weeks, consider "hugging coast" inshore of current (slower, safer) or rare Suez diversion.
- ITCZ / Doldrums Crossings (Legs 2A, 8): Weeks of < 1 kt progress possible. Solar (1.25 mph) is only power. Mitigation: Use forecasts to find "Equatorial Rossby Waves" or Westerly Wind Bursts (WWB) for brief Kite assists West.
- Indonesian Throughflow (Leg 4): Complex, reversing tidal currents up to 4 kts in narrow straits (Lombok, Sape, Alas). Kite unusable (land shadow, gusty). Mitigation: Strict tidal planning (slack water transit), solar only. Adds unpredictability.
📈 Sensitivity Analysis
| Scenario | Kite Efficiency | Current Assist | Wait Time | Total Duration |
|---|---|---|---|---|
| Optimistic (Perfect Windows, Strong Currents) | 95% (VMG 2.5 kts) | +1.0 kts Avg | 10 Days | ~295 Days |
| Base Case (Presented Above) | 85% (VMG 2.26 kts) | +0.7 kts Avg | 35 Days | ~320 Days |
| Pessimistic (Weak Trades, Agulhas Stall, ITCZ Stalled) | 70% (More Solar) | +0.3 kts Avg | 60 Days | ~380 Days |
💡 Key Operational Takeaways
- Kite is King in Trades: 70% of distance (Pacific/Indian/S. Atlantic) done at ~3.0 kts VMG West. Without Kite (Solar only 1.1 kts), trip takes ~700+ Days.
- Zig-Zag Cost: The 30° Downwind limit adds 15% distance (1/cos30) but doubles speed vs Solar. Net Win.
- Agulhas is the Pacing Item: It dictates the schedule. You arrive Mauritius when the weather window opens, not when you feel like it.
- No Suez Canal: Red Sea winds (NW) oppose Westbound transit. Kite useless. Solar only = 40+ days added. Panama is the only viable low-latitude choke point.
- Battery/Sizing: 18 hrs @ 1 mph requires significant storage. Ensure array oversizing for cloudy trade-wind days (cumulus shading).