Holtrop & Mennen's ship powering method

Ship designers are familiar with the Holtrop & Mennen' method (H & M) to calculate the relationship between power and ship speed, used for years in the technical offices of shipyards and engineering sites. Due its great interest I programmed this method and have included it in GetxoNaval website as part of the calculation procedures used to perform preliminary design of a merchant ship.
The H&M method was developed by J.Holtrop & G.G.J.Mennen from MARIN "Maritime Research Institute" in Wageningen (Netherlands), based on the results of hundreds of tests with ship models and correlations with the data recorded in actual sea trials.
This method affords results considered satisfactory in 95% of cases, in the preliminary design stage, provided that the range of the variables is within the limits given in Ref.1, summarized in these figures:

Ship type	No. Froude máx.	Cp min-max	L/B min-max	B/T min-max
Tanker, Bulkcarrier	0,24	0,73-0,85	5,1-7,1	2,4-3,2
Coaster, Tug	0,38	0.55-0.65	3.9-6.3	2.1-3.0
Container C.	0.45	0.55-0.67	6.0-9.5	3.0-4.0
Carguero	0.30	0.56-0.75	5.3-8.0	2.4-4.0
Ro-ro	0.35	0.55-0.67	5.3-8.0	3.2-4.0

At this link to Getxo Naval site you access the main page and can choose between the Spanish and English versions of the H&M method. In addition to presenting the power-speed results in tabular form, a graph is displayed with delivered power curves in service and trial concitions, as shown herein.

Ref.1 An approximate power prediction method. J.Holtrop & G.G.J.Mennen - International shipbuilding Progress 1978 -