Planing Condition

[bulgafabio]

I'm making a thesis work on VPP. We have an experimental sailing yacht (skiff type,4.6 meters long) and we have lot of troubles in calculating the total resistance of the hull because it's of planing type. The problems are:
-don't have a theoretical model to compute the resistance for planing,only for displacement
-dedicated software we found cost so much and we cannot afford buying them
In this way our VPP is unusable an so we cannot make the optimization we would do.
Can someone please help us?

[Rick Willoughby]

Go here:
http://illustrations.marin.ntnu.no/hydrodynamics/resistance/planing/index.html

[bulgafabio]

Thanks for your answer. I still have some problems:
-the graph starts from 15 Kn and for our boat is practically the maximum speed.
-where can I find Savitsky's paper about hydrodynamic design of planning hulls?

[Rick Willoughby]

Search this site. Savitsky is referenced quite often showing a pdf of the paper and there is a spreadsheet for it as well.

It is not the easiest theory to apply.

For practical size boats, the 15 kts is as low as they can go before they move into a transition mode. There is also lengthy discussion on semi-displacement on this site.

Rick W.

[yades]

try to look at the paper I post time ago on this forum http://www.boatdesign.net/forums/showthread.php?t=20495 ( Planing Hull 1-Master.PDF) see if it helps.....savitsky's computational procedure is clearly explained plus the equations used which are explained/enclosed.....
the procedure is clear enough and results could be helpful.....

:cool: :cool:

[bulgafabio]

Thanks Yades,
I still have some little problems:
- My boat is a sailing yacht so I must be sure that your algoritms are ok not only for a powerboat but still for a sailing yacht
- In your paper there's a graph at page 15(figure 10) and I would like to know if it's experimental or generated because my values of Lp/b are about 5 and so in this way the graph for me is unuseful.
- In the first step for the computing you say ''calculate cl0 from given values'' consider that I've only the hull so What have I to do?
Thanks for your great help, I'm closer now, need only little specifications.