Fast Speed Estimation

[RANCHI OTTO]

This diagram is based on 31 sea trial results of boats equipped with piercing screws. KR is the E.Clement coefficient.
Perhaps can be of utility for a fast speed estimation.

[jehardiman]

Any data on the Lp and Bpx along with plotting by volumetric Froude number for each hull? There seems to be some significant scatter ( see the values of KR =~ 17.5) and I wonder how much that plays in this since he uses Fvol as a primary variable in some of his other work. In the Series 62 data analysis there was a distinct linear correlation between R/W to Fvol with scatter provided by the Lp/Bpx ratio (see PNA, 1988, V2 ch5,sect 9.2).

[RANCHI OTTO]

The propulsive efficiency of propellers and the OPC coeff. are related to absolute speed and the Froude volume coeff. is used vs specific resistance permitting extrapolations.

The ratio L/B, deadrise angle, L.c.g. for high speed boats are very closed and the scatters are due to the fact that there are very good, medium and poor boats at sea...
This is only a diagram that permit to evaluate in few seconds where your design is located related to 31 boats, nothing else.

[RANCHI OTTO]

Perhaps the significant scatter is due to some problems of the boats during sea trials.....
The figures are derived from sea trial results and given to me from engines, propellers and propulsion devices manufactures.

My 2 last design have KR = 13.5 > speed in tropical cond. = 41 knots and KR = 17 speed in tropical condition = 52 knots. The hulls designed acc. to ASD (Arrow System Design).