| General Information | ||||
|---|---|---|---|---|
| January 26, 2006 10:53:02 AM | RhinoMarine 3.2.9 | |||
| HydroComp Drag Prediction Library by HydroComp 1.15.0021 | ||||
| Company | Project Description | |||
| Your Company Name here | Demo project | |||
| Condition Information | |||||
|---|---|---|---|---|---|
| Prediction Parameters | |||||
| Method: Savitsky | Speed: OK | Hull: OK | |||
| Design Margin | 10 | % | Water Type | Salt | |
| Design Speed | 24.000 | knots | Water Density | 64.045 | pounds/feet^3 |
| OPC | 55 | % | Water Viscosity | 0.00001279 | feet^2/s |
| Vessel Data | |||||
| Max planing length | 21.960 | feet | LCG fwd transom | 7.882 | feet |
| Max planing beam | 6.530 | feet | VCG above origin | 0.500 | feet |
| Displacement bare | 2,917.000 | pounds | |||
| Parameter Range Check | |||||
| LCG/Bch [0.6 - 3] | 1.210 | Deadrise mid-length [0 - 30] | 19.880 | deg | |
| Fn(Bch)-max [1.43 - 13] | 2.790 | CLB-max [0 - 0.5] | 0.040 | ||
| Thrust Line | |||||
| Shaft angle to BL | 11.000 | deg | LCE fwd transom | 1.112 | feet |
| VCE above origin | -0.500 | feet | |||
| Drag Results | ||||||
|---|---|---|---|---|---|---|
| Drag Prediction | ||||||
| Speed (knots) | Fv | Trim (deg) | Rbare (pound) | Rtotal (pound) | PEtotal (horsepower) | PBtotal (horsepower) |
| 10.000 | 1.570 | 3.390 | 354.580 | 390.040 | 11.970 | 21.764 |
| 12.000 | 1.890 | 3.860 | 383.370 | 421.700 | 15.530 | 28.236 |
| 14.000 | 2.200 | 4.020 | 398.720 | 438.590 | 18.840 | 34.255 |
| 16.000 | 2.520 | 3.910 | 409.530 | 450.480 | 22.120 | 40.218 |
| 18.000 | 2.830 | 3.650 | 422.360 | 464.600 | 25.660 | 46.655 |
| 20.000 | 3.150 | 3.370 | 440.640 | 484.700 | 29.750 | 54.091 |
| 22.000 | 3.460 | 3.070 | 464.680 | 511.150 | 34.510 | 62.745 |
| 24.000 | 3.780 | 2.810 | 495.100 | 544.610 | 40.110 | 72.927 |
| 26.000 | 4.090 | 2.560 | 531.450 | 584.600 | 46.640 | 84.800 |
| 28.000 | 4.410 | 2.350 | 573.810 | 631.190 | 54.230 | 98.600 |
| 30.000 | 4.720 | 2.160 | 621.490 | 683.630 | 62.940 | 114.436 |
| Speed (knots) | Fn(Bch) | Rbare/W | Porpoising | Eff planing beam (feet) | Eff deadrise (deg) | See Prediction Check Notes |
| 10.000 | 1.170 | 0.122 | Stable | 6.510 | 17.910 | Check=1,2 |
| 12.000 | 1.400 | 0.131 | Stable | 6.510 | 17.910 | Check=2 |
| 14.000 | 1.630 | 0.137 | Stable | 6.510 | 17.910 | Check=2 |
| 16.000 | 1.870 | 0.140 | Stable | 6.510 | 17.920 | OK |
| 18.000 | 2.100 | 0.145 | Stable | 6.510 | 17.920 | OK |
| 20.000 | 2.330 | 0.151 | Stable | 6.510 | 17.930 | OK |
| 22.000 | 2.570 | 0.159 | Stable | 6.510 | 17.940 | OK |
| 24.000 | 2.800 | 0.170 | Stable | 6.510 | 17.940 | OK |
| 26.000 | 3.030 | 0.182 | Stable | 6.510 | 17.950 | OK |
| 28.000 | 3.260 | 0.197 | Stable | 6.510 | 17.960 | OK |
| 30.000 | 3.500 | 0.213 | Stable | 6.510 | 17.980 | OK |
| Drag Reduction at Design Speed | ||
| Parameter | To reduce drag | Sensitivity |
|---|---|---|
| Eff planing beam | Decrease | 0.390 |
| Eff deadrise | Decrease | 0.290 |
| LCG fwd transom | Decrease | 1.520 |
| Shaft angle to BL | Increase | 0.010 |
| General Notes | ||
| Rbare is the predicted bare hull resistance. Rtotal is the predicted total resistance which includes the user-specified design margin. | ||
| PEtotal is predicted total effective power. It is the power that the propeller must deliver to the water for the specified speed. Required engine power will be substantially higher (sometimes as much as twice the effective power) because it must account for the propulsive efficiency. | ||
| A Sensitivity index with a higher value has a greater influence on drag. Sensitivity values greater than 1.0 are considered significant. | ||
| Prediction Check Notes | ||
| 1. A wetted keel length greater than the boat length indicates that the boat is running at small trim and the bow will be immersed. In this condition, the prismatic analysis of the Savitsky prediction will be unreliable and can significantly under-predict the actual drag. However, as this condition typically occurs at pre-planing speeds, the internal hump speed correction accounts for this in the prediction of drag. There is no correction for trim. | ||
| 2. The Froude number based on chine beam (FnBch) is a good indicator of the development of the spray root and the magnitude of the planing lift coefficient. Results for speeds outside of the Savitsky data set (most often for low speeds below the range) may be unreliable. | ||
| 3. The lift coefficient (CLb) is a ratio of displacement to the square of speed and chine beam, with a correction for deadrise. This coefficient is a measure of the weight loading for the given planing geometry. We caution against using this method for hulls that produce this data range error. | ||
| 4. The original testing of the models used in the Savitsky analysis were limited to a given range of trim values. Predicted trim values that are beyond the range of the original data set may be unreliable. | ||