LCB light displacement?

For a light displacement type hull form (lenght/displacement = 6.3) that is capable of 'semi-planning', what is the optimum location of centre of buoyancy for Fn = 0.35, Fn = 0.45, and beyond please? The literature I am studying only refers to medium displacement vessles. Is there much difference for lighter yachts even though speeds over Fn = 0.45 may not be frequent.
Thanks for your time and trouble, Glenn.

 

Unscientifically, I find 55% of LWL works well. If pressed, I'm sure I could find a scientifical reason.....

Steve Baker

 

What's the Cp ? It would seem to me that would be a good starting point (higher speed = LCB further aft).

 

I have gone for a Cp of approximately 0.57 in accordance with her light displacement ( in old terms I think she is about 112) and pure racing pedigree coupled with a very high ballast ratio of 62%. In designing racing yachts, I'm trying to establish how much further aft we should place the LCB compared to say cruiser/racers at between 3 and 4%. I appreciate all replies, Glenn.

 

"Guest" says: What's the Cp ?

I typically aim at around 0.56 to 0.58-ish, but have gone as high as 0.6 on occasion.

Steve

 

Thanks Steve. That's good news as I was concerned that 0.57 to 0.58 was a little too large. Old habits are hard to break! But that is was the numbers kept telling me, so I'll stick with it and go for a LCB of 55% of DWL. My DWL/ Tc is 20.5. How does that sit with you? And may I ask which software you use please. Thanks, Glenn.