Maxsurf Resistance Method

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Ruffner Sedurifa

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Hi All . For an FRP V-shaped hull Fishing vessel (LOA= 27.75m, B= 5.24m) what method is suitable for resistance and power estimates? Is Holtrop ok to use?
 
The attached table outlines the range of application of the method for various types of vessels.
 

Attachments

  • Holtrop Range og Application.png
    Holtrop Range og Application.png
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Hello all,
I've some inconsistencies in the Maxsurf Resistance Module, someone could indicate me some possibilities to check and fix it?

upload_2025-4-2_10-23-42.png
upload_2025-4-2_10-24-11.png
 
I think you don't need more surfaces than the inner npl-hull and outer npl-hull. You can delete the others. If you want, you could also keep Surface Number 1, but Maxsurf doesn't need it for its calculations.
Once that's done, define the surfaces as symmetrical and move them, for example, 0.7 m transversally.
I think this will improve the calculations considerably.
Snap3.jpg
 
Last edited:
TANSL said:
I think you don't need more surfaces than the inner npl-hull and outer npl-hull. You can delete the others. If you want, you could also keep Surface Number 1, but Maxsurf doesn't need it for its calculations.
Once that's done, define the surfaces as symmetrical and move them, for example, 0.7 m transversally.
I think this will improve the calculations considerably.
View attachment 201775
Click to expand...
Hello,
I'm try to define a simplification hull directly on Modeler, defining different frames by Markers.
However, I can't close properly the bow.
Any suggestion?
upload_2025-4-9_14-16-40.png

upload_2025-4-9_14-17-13.png
 
TANSL said:
Yes, like most of us who use MaxSurf, you create a model in Rhino or AutoCAD (AutoCAD is better than Rhino) and export it to MaxSurf. MaxSurf's modeler is the most unfriendly I've ever seen.
Click to expand...
That was my first intention, but due to I get some problems when I defined the ref frame, I started to get the points which define the surface and reproduce the hull in the Modeler
My problem is that the values at low speed makes me doubt.

upload_2025-4-9_16-35-6.png
 
TANSL said:
The attached table outlines the range of application of the method for various types of vessels.
Click to expand...
Hi TANSL, hope all is well. I am doing a preliminary design of a ropax double ended ferry and am a bit confused whether holtrop method would be feasible. I am getting confused as i am getting different results when actually hand calculating it andwhen calculating it on MAXSURF. Can not use any of the excel ready made templates since when i leave some things out, as i am analyzing a double ended ferry and things like appendage area are left out it would not compute. Please not that i did not put the model in max surf just put the dimensions.
 
Welcome to the forum.
I'm not entirely sure how Maxsurf can calculate anything if you haven't entered the model, only its dimensions.
On the other hand, I wouldn't trust Maxsurf's results too much because there is some data, necessary for Holtrop's calculations, that Maxsurf doesn't require (the appendices, for example). I'm not saying Maxsurf does it wrong; I'm just saying I don't know how it does it and, therefore, I don't trust it too much.
Holtrop doesn't consider those types of boats, but in any case, given that your boat's stern is more hydrodynamic than a conventional stern, Holtrop's results may be more pessimistic but acceptable for a preliminary estimate.
 
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