Michlet and hard chines

[Windvang]

I am designing a long and narrow boat with a round bottom and a hard chine, on model tests I have noticed the wave pattern is significantly different from full round bilged hulls. I would like to do some resistance calculations on it using Michlet, does this make any sense or will Michlet totally ignore the chines in it's calculations?

thanks,
Arthur

[Rick Willoughby]

The only part that matters with Michlet is what is below the surface. If you have complex geometry then you need to have more waterlines and more stations. Michlet will give a useful result.

You should consider using Godzilla to produce an optimised hull to your constraints. You can force a hard chine if you want.

If you give me some hull constraints I can give you an in.mlt file to use with Godzilla.

Rick W.

[Windvang]

Thanks for the answer.

I can produce a good .mlt from Delftship, I think, or ar there some other things to concider? I am just worried abouth the influence of the chine in Michlet or any other software as it just looks to have a more impact than any other "basic" input.

Regards,
Arthur

[Rick Willoughby]

Arthur
Michlet handles chines.

If you post the basic hull constraints I can see what Godzilla produces. The parameters needed are things like design speed, maximum length, minimum length, displacement, stability (metacentric height), beam constraints (if any), ease of construction (chines for example), turning abilty etc

I normally start with the least constraints and see what an uncompromised shape looks like. Then I start adding other constraints to make it practical.

Rick W.

[Rick Willoughby]

Arthur
If you already have the model and a Delftship drawing then the .mlt will be fine. I usually modify the speed range in the .mlt file.

Michlet will also produce an image of the wave pattern so you can compare this with a photo of the waves produced by the model.

Rick W.

[Leo Lazauskas]

Originally Posted by Windvang

I am designing a long and narrow boat with a round bottom and a hard chine, on model tests I have noticed the wave pattern is significantly different from full round bilged hulls. I would like to do some resistance calculations on it using Michlet, does this make any sense or will Michlet totally ignore the chines in it's calculations?

thanks,
Arthur

If you use a sufficient number of waterlines (e.g. > 11) then there will be no problem with hard chines. Internally, Michlet's calculations are exact for piece-wise linear or piece-wise parabolic sections.

Regards,
Leo.