Hullform software from Blue Peter Marine system

Hi, I would like to check if anyone that is provision in the software can provide me with an answer to whether the software can differentiate a same vessel type (same length, breath, depth and displacement) with and without a bulbous bow feature?

This is because my results have indicated a lower resistance in the file without bulbous bow feature where it should be the opposite. It has confused me as to whether the software has the ability to analyse correctly.

 

The manual of the software can be found here: http://alastor.daviel.org/hullform/manual_hullform.pdf

The chapter about drag prediction starts at the page 75. Apparently, the only adopted method for drag prediction which might take the bulbous bow into account is the Holtrop-Mennen, but... check this line:


So, basically, the software is not able to include the effects of the bulbous bow. Hence, it is possible that the program always calculates a higher drag with the bulbous bow simply because all it "sees" is a bigger wetted surface of the added bulb and hence more friction.

Cheers

 

Bulbous bow does not mean that total resistance to be lowered. The bulb, if appropriate, is well placed and depending on the type of ship, its displacement and its speed, may decrease, or not, the wave making resistance but what is certain is that it increases the frictional resistance.

 

hi daiquiri and TANSL, thank you for the information. It has indeed helped me alot in understanding the program especially with the manual of the software link provided. Thank you.