Calculation Method for Decrease of Ship Speed in Actual Seas

In order to calculate ship speed in actual seas, it is important to estimate added resistance

due to winds and waves. Especially added resistance in waves is one of the predominant components

and it should be estimate with accuracy. NMRI developed a calculation method for decrease of

ship speed in actual seas. In the method correction for the added resistance in waves is applied to

that in short waves from the point of accuracy. The correction is easily carried out by a tank test

in regular heading waves. The corrected added resistance in waves gives a good agreement with

the experiment data.

1. Added resistance in regular waves

(1-1) Calculation method

(1-2) Experimental method

(1-3) Calculation results

2. Added resistance in short crested irregular waves

(2-1) Calculation method

(2-2) Calculation results

3. Added resistance due to winds

(3-1) Calculation method

4. Decrease of ship speed

(4-1) Calculation method

(4-2) Calculation results

　　　　

Q&A

References

1) M. Tsujimoto, K. Shibata, M. Kuroda and K. Takagi, “A Practical Correction Method

for Added Resistance in Waves”, Journal of The Japan Society of Naval Architects and

Ocean Engineers, Vol.8, pp.147-154, 2008.

2) M. Tsujimoto, M. Kuroda, K. Shibata, T. Fujiwara and S. Ohmatsu, “Development

of a Practical Calculation Method for Added Resistance in Short Waves”, The 8th Research

Presentation Meeting of National Maritime Research Institute, June 25, 2008 [PDF]

3) M. Tsujimoto, M. Kuroda, K. Shibata, N. Sogihara and K. Takagi, “On a Calculation of

Decrease of Ship Speed in Actual Seas”, Journal of The Japan Society of Naval Architects and

Ocean Engineers, Vol.9, pp.79-85, 2009.

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