The Submarine Torpedo Boat
Its Characteristics And Modern Development

DESIGN OF THE SUBMARINE TORPEDO BOAT 69 Therefore the total frictional resistance equals .0091 X3700 X 161.825 = 82960 lbs. and the frictional E.H.P. equals .00307 X 82960 = 255 E.H.P., By subtracting the frictional resistance of the model from the tow rope resistance, we have the residual resist- ance equal 4.9435 —.4075 = 4-536 lbs. The corresponding residual resistance of the ship equals Rte = 4.536 X 1443 - 7838 lbs. 123 and at 16 knots the E.H.P. required to overcome the residual resistance equals .00307X16X 7838 = 385 E.H.P.„ The total E.H.P. will then be 255 +385 = 640 for the bare hull alone. The resistance due to the appen- dages must be added to this to make up the total E.H.P. The hull appendage resistance may be roughly taken to be about 10 per cent of the hull resistance and may be . B assumed to vary directly as the ratio LWL and while this is probably not strictly correct any error which might occur will be on the right side and will result in a slightly higher estimation of the resistance than actually exists. The range of this value as determined by numerous experiments is found to be from 5 to 20 per cent. Should the model be towed with any of the appendages the per- centage resistance due to these appendages should be subtracted from the total appendage resistance and the