Stepped Hull Design

[an2reir]

Good Morning!


I work on the design of a new stepped hull

Some people did express the opinion the tips of the steps need to be aligned.

Should the tips of the steps be on the same line with the tip of the rear end of the hull bottom?


Thank you for your feedback

 

[Ad Hoc]

Hi Andrei,

Why have you elected to use steps... ?
There are many do's and dont's for using steps, and it depends upon many issues, hence the question.

 

[an2reir]

Hi Ad Hoc

Greetings from France thank you for your feedback
I need to design a hull that reaches a speed 60 kn.

 

[Ad Hoc]

There are successful designs (and research) that suggest a single step..located at 25% of Lwl fwd of the transom is more than adequate.

What length of hull is it?

 

[an2reir]

Hi Ad Hoc thank you for your kind suggestion . In my case the requirements were to have two steps and lenght of hull 45 ft. I hear the boats are being judged by some boat dealers on the criteria the bottom steps tips to be aligned with the rear bottom end tip. I wonder if there may be some true in this validation criteria.
I already did speed predictions for the hull without steps. I plan to do CFD simulations to optimise the hull

 

[Ad Hoc]

.... I hear the boats are being judged by some boat dealers on the criteria the bottom steps tips to be aligned with the rear bottom end tip. ...

I think you would need to read up more of why they are suggesting this, since there are so many variables that come into play with regards to how many and location of the steps.
However, since there is some element of "salesmanship" in this for some companies prompting their designs, I strongly suspect that many features are not truly universal. But i'm not an expert on stepped hulls per se.

 

[Alik]

I would suggest to check bottom loading first. If it is not too low, then hydrodynamically there is no need for steps. In such cases, steps would only be a marketing stuff and can be of any shape

 

[Mr Efficiency]

This reminds me that a couple of steps need replacing in my front stairs.

 

[Mr Efficiency]

Whatever happened to centreline "planks" in fast boats, firmed the ride up too much ? Certainly helped reduce wetted area.

 

[an2reir]

Thanks for feedback from the beautiful France! There are opinions the tips of the steps are to be in line with the rear tip of the boat bottom

 

[an2reir]

Greetings from France and I wishing you an excellent weekend
I did some study of the stepped hull CAD model in CFD software - it appears the tips of the steps may not need precise aligning with the rear hull bottom tip