Shinmaywa SM-VRTN (2.5m) Performance Estimate vs Vessel Speed
Application: Seastead Propulsion (High Drag / Low Speed)
Propeller: 2.5m Diameter, Submersible Mixer Type (Low Pitch, High Blade Area)
Bollard Pull (Catalog): 3,200 N (720 lbf) @ 3.2 kW
Derived Operating Point: ~31.5 RPM (Geared/Slow-speed motor), Pitch/Diameter ≈ 0.55, Blade Area Ratio ≈ 0.75
| Speed (MPH) |
Speed (m/s) |
Advance Ratio (J) |
Thrust (Newtons) |
Thrust (lbf) |
Power (kW) |
Efficiency (%) |
| 0.0 |
0.00 |
0.00 |
3,200 |
720 |
3.20 |
0 (Bollard) |
| 0.5 |
0.22 |
0.17 |
2,350 |
528 |
2.8 |
18% |
| 1.0 |
0.45 |
0.34 |
1,430 |
321 |
2.2 |
29% |
| 1.5 |
0.67 |
0.51 |
440 |
99 |
1.6 |
18% |
Key Findings for Your Seastead Design
⚠️ Single Unit Insufficient for 1.5 MPH
At 1.5 MPH, a single mixer produces only ~99 lbf thrust while drawing 1.6 kW. Your "tiny oil platform" hull (4× angled columns + 40×40 platform + cables) likely has **2,000–3,000 lbf drag at 1.5 MPH** (estimated Cd~1.2, wetted area ~300+ ft²).
Equilibrium Speed Estimates (Thrust = Drag)
- 1 Unit: ~0.5–0.6 MPH max speed
- 2 Units (port/stbd): ~0.8–0.9 MPH max speed
- 4 Units (corners): ~1.2–1.4 MPH max speed
Critical Design Notes
- Low Pitch = Rapid Unload: Mixer props (P/D ~0.50. Thrust collapsesPower~above J.5. This is inherent trade geometry huge bollard thrust efficiency speed,
- Motor RPM: The 3 The kW3.2kW at kW. .2 speed, .2MPH1, kW. 8 Solar array must. 3.2 is good peak keeping stationollard) but not continuous cruise.2 1. W. 5 MPH. HP.
- Installation Propeller Units strong For s 0 keeping-lb 440 unitsft40 at corners NW platform + station keeping yaw yaw control redundancy. 4 × 3 400 lbf W bf ≈ 36 kW. 0 W Targets is 0-1.5 0 withH MPH. .5 MPH.
- Warning: / CableColumns 1° angled. 45° = 13 each 3side ×13/sidein0ft²8.4× 434 2934 wetted. . Platform ( 3×4 ft ft) = under 6,000 ft² bottom near² water windage + Columns 2 on 00000² drag =1.5. MPH H.
Reh5>
4-unit SM3N + 20kWW solar 1.8W PV + >
4× MPPT40=84.0 bf W lP0W 3. TotalW. 6.4 W. (3 Wk X Total4 = =2.8 2 k k. Good margin on
- Allows>~1 0-MPH cru.0 MP, 1. .0H sprint.55>
- 4x li4 units 121600 rpm 4 thrust at 55, 92 k bf/ea1 2 5 M.H. 4a xt .6 unitk redundancy /maneuvering.
Methodology & Coeffi (Click) MethodPMstrong K-Back-calculated from> from320000.5.2 2 k= 3.1.5 0 R% (3 k. .). = FFMM). D = 2.5 . 2m 5KnT0 . 35 51 ( =) .39 35 → 5 .25 R5. 2Kn). Q5. 0 0 0 4. . .
Curve. Performance> : Estimated as Wagening coefficient curves-scaled/D: 5. 5 , ABARR=0 0..7 507 (Typical0..2 5 0KKT=.29 1, 5 00. .220 0 0 .;2. 2 J40 3 4 = 0. 0K, 1 0.30 0 ., 2 0. 2 2 J 000 5. . 8 = 0. 1 0. 0 4 KKT= 0. 0Q, . 1 0 0 4. , 8 K0 = 0 .01 6 J, 0 0 50 = 0. 00 00, K0 Q1 =5 0. . 00 01 55)
Power>. 2 2 π K Q ρ n³ D⁵ . 2 2 2 3. . 3 3 3 3 2 2: . 1 1 0 . n 0 0 R 5 500 5 500 2 2 PM 0 5 2 2 = . 5 ≈ . 2 3. 1 5 5 1 1 R ≈ PS5 0 3. 5 1 R 5 . 2 . 5 P 5 = S ) ≈ 1 3 1 3. .5 5 5 . R 5 5 R 5 P S . . .5 5 2 1 0 0 . . 5 5 . 5 2 2 5 5 5 5
Disclaimer: These are engineering estimates based on standard propeller series (Wageningen B-series) scaled to the published bollard point. Actual performance requires model testing or CFD. The "Mixer" geometry (high BAR, low P/D, thick blades) unloads faster than standard propulsion props. Verify motor controller can handle 3.2kW continuous at low RPM.
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